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rev. 0 information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. a ad73460 one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-470 0 www.analog.com fax: 781/326-8703 ? analog devices, inc., 2001 six-input channel analog front end features afe performance six 16-bit a/d converters programmable input sample rate simultaneous sampling 72 db snr 64 ks/s maximum sample rate C 80 db crosstalk low group delay (25 s typ per adc channel) programmable input gain single supply operation on-chip reference dsp performance 19 ns instruction cycle time @ 3.3 v, 52 mips sustained performance single-cycle instruction execution single-cycle context switch 3-bus architecture allows dual operand fetches in every instruction cycle multifunction instructions power-down mode featuring low cmos standby power dissipation with 400 cycle recovery from power-down condition low power dissipation in idle mode functional block diagram serial port sport 2 ref adc3 analog front end section adc1 adc2 adc4 adc5 adc6 external address bus serial ports sport 0 shiftermacalu arithmetic units memory programmable i/o and flags byte dma controller timer adsp-2100 base architecture power-down control program sequencer dag 2 data address generators program memory address data memory address program memory data data memory data dag 1 16k dm (optional 8k) 16k pm (optional 8k) external data bus full memory mode sport 1 ad73460 general description the ad73460 is a six-input channel analog front-end processor for general-purpose applications including industrial power m eter- ing or multichannel analog inputs. it features six 16-bit a/d conversion channels, each of which provides 72 db signal-to-noise ratio over a dc-to-2 khz signal bandwidth. each channel also features a programmable input gain amplifier (pga) with gain settings in eight stages from 0 db to 38 db. the ad73460 is particularly suitable for industrial power metering as each channel samples synchronously, ensuring that there is no (phase) delay between the conversions. the ad73460 also features low group delay conversions on all channels. an on-chip reference voltage of 1.25 v is included. the sampling rate of the device is programmable with separate settings offering 64 khz, 32 khz, 16 khz, and 8 khz sampling rates (from a master clock of 16.384 mhz), while the serial port (sport2) allows easy expansion of the number of input channels by cas- cading an extra afe external to the ad73460. the ad73460 s dsp engine combines the adsp-2100 family base architecture (three computational units, data address gen- erators, and a program sequencer) with two serial ports, a 16-bit internal dma port, a byte dma port, a programmable timer, flag i/o, extensive interrupt capabilities, and on-chip program and data memory. the ad73460-80 integrates 80k bytes of on-chip memory configured as 16k words (24-bit) of program ram and 16k (16-bit) of data ram. the ad73460-40 integrates 40k bytes of on-chip memory configured as 8k words (24-bit) of program ram and 8k (16-bit) of data ram. power-down circuitry is also provided to meet the low power needs of battery-operated portable equipment. the ad73460 is available in a 119-ball pbga package.
rev. 0 ad73460 C2C topic page features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 functional block diagram . . . . . . . . . . . . . . . . . 1 general description . . . . . . . . . . . . . . . . . . . . . . . . . 1 specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 timing characteristics . . . . . . . . . . . . . . . . . . . . . 5 absolute maximum ratings . . . . . . . . . . . . . . . . . 6 ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 pbga ball configuration . . . . . . . . . . . . . . . . . . . . 7 pin function descriptions . . . . . . . . . . . . . . . . . . 8 architecture overview . . . . . . . . . . . . . . . . . . . . 10 analog front end . . . . . . . . . . . . . . . . . . . . . . . . . . 10 functional description C afe . . . . . . . . . . . . . . . 11 encoder channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 signal conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 programmable gain amplifier . . . . . . . . . . . . . . . . . . . . . 11 adc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 analog sigma-delta modulator . . . . . . . . . . . . . . . . . . . . 12 decimation filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 adc coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 voltage reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 afe serial port (sport2) . . . . . . . . . . . . . . . . . . . . . . . 13 sport2 overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 sport register maps . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 master clock divider . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 serial clock rate divider . . . . . . . . . . . . . . . . . . . . . . . . . 14 decimation rate divider . . . . . . . . . . . . . . . . . . . . . . . . . 14 control registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 resetting the afe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 power management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 channel selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 interfacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 cascade operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 functional description dsp . . . . . . . . . . . . . . 20 serial ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 dsp section pin descriptions . . . . . . . . . . . . . . . 21 memory interface pins . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 terminating unused pins . . . . . . . . . . . . . . . . . . . . . . . . 22 interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 topic page low power operation . . . . . . . . . . . . . . . . . . . . . . . 23 power-down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 idle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 slow idle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 system interface . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 clock signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 modes of operation . . . . . . . . . . . . . . . . . . . . . . . . 25 setting memory mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 passive configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 active configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 memory architecture . . . . . . . . . . . . . . . . . . . . . . 25 program memory . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 program memory (full memory mode) . . . . . . . . . . . . . 26 program memory (host mode) . . . . . . . . . . . . . . . . . . . . 26 data memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 data memory (full memory mode) . . . . . . . . . . . . . . . . 26 i/o space (full memory mode) . . . . . . . . . . . . . . . . . . . . 26 composite memory select ( cms ) . . . . . . . . . . . . . . . . . . 26 boot memory select ( bms ) disable . . . . . . . . . . . . . . . . 27 byte memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 byte memory dma (bdma, full memory mode) . . . . . 27 internal memory dma port (idma port; host memory mode) . . . . . . . . . . . . . . . . . . . . . . . . . . 27 bootstrap loading (booting) . . . . . . . . . . . . . . . . . . . . . . 28 idma port booting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 bus request and bus grant (full memory mode) . . . . . . 28 flag i/o pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 instruction set description . . . . . . . . . . . . . . . 29 designing an ez-ice-compatible system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 target board connector for ez-ice probe . . . . . . . . . . . 30 target memory interface . . . . . . . . . . . . . . . . . . . . . . . . . 30 pm, dm, bm, iom, and cm . . . . . . . . . . . . . . . . . . . . . 30 target system interface signals . . . . . . . . . . . . . . . . . . . . 30 analog front end (afe) interfacing . . . . . . . 30 dsp sport to afe interfacing . . . . . . . . . . . . . . 30 cascade operation . . . . . . . . . . . . . . . . . . . . . . . . . 31 interfacing to the afe s analog inputs . . . . . . . . . . . . . . 31 digital interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 outline dimensions . . . . . . . . . . . . . . . . . . . . . . . . . 32 table of contents
rev. 0 C3C ad73460 (avdd = 3.0 v to 3.6 v; dvdd = 3.0 v to 3.6 v; dgnd = agnd = 0 v, f mclk = 16.384 mhz, f sclk = 8.192 mhz, f s = 8 khz; t a = t min to t max , unless otherwise noted.) specifications ad73460b parameter min typ max unit test conditions/comments 1 reference refcap absolute voltage, v refcap 1.125 1.25 1.375 v refcap tc 50 ppm/ c 0.1 f capacitor required from refcap to agnd2 refout typical output impedance 130 ? absolute voltage, v refout 1.125 1.25 1.375 v unloaded minimum load resistance 1 k ? maximum load capacitance 100 pf adc specifications maximum input range at vin 2, 3 1.644 v p-p measured differentially C 2.85 dbm nominal reference level at vin 1.1413 v p-p measured differentially (0 dbm0) C 6.02 dbm absolute gain pga = 0 db C 1.2 +0.6 db 1.0 khz signal to (noise + distortion) pga = 0 db 71 db 0 hz to 4 khz; f s = 8 khz; f in = 60 hz pga = 0 db 70 72 db 0 hz to 2 khz; f s = 8 khz; f in = 60 hz total harmonic distortion pga = 0 db C 77 C 72 db intermodulation distortion C 76 db pga = 0 db idle channel noise C 70 db pga = 0 db crosstalk adc-to-adc C 83 db adc1 input at idle adc2 to adc6 input signal: 1.0 khz C 95 db adc1 input at idle adc2 to adc6 input signal: 60 hz dc offset C 30 +10 +45 mv pga = 0 db power supply rejection C 55 db input signal level at avdd and dvdd pins 1.0 khz, 100 mv p-p sine wave group delay 4, 5 25 s 64 khz output sample rate 50 s 32 khz output sample rate 95 s 16 khz output sample rate 190 s 8 khz output sample rate input resistance at vin 2, 4 25 k ? 6 dmclk = 16.384 mhz phase mismatch 0.15 degrees f in = 1 khz 0.01 degrees f in = 60 hz frequency response (adc) 7 typical output frequency (normalized to f s ) 00db 0.03125 C 0.1 db 0.0625 C 0.25 db 0.125 C 0.6 db 0.1875 C 1.4 db 0.25 C 2.8 db 0.3125 C 4.5 db 0.375 C 7.0 db 0.4375 C 9.5 db > 0.5 < C 12.5 db
rev. 0 C4C ad73460 C specifications ad73460b parameter min typ max unit test conditions/comments logic inputs v inh , input high voltage v dd C 0.8 v dd v v inl , input low voltage 0 0.8 v i ih , input current 10 a c in , input capacitance 10 pf logic outputs v oh , output high voltage v dd C 0.4 v dd v |iout| 100 a v ol , output low voltage 0 0.4 v |iout| 100 a three-state leakage current C 10 +10 a power supplies avdd1, avdd2 3.0 3.6 v dvdd 3.0 3.6 v i dd 8 see table i notes 1 operating temperature range is as follows: C 20 c to +85 c. therefore, t min = C 20 c and t max = +85 c. 2 test conditions: input pga set for 0 db gain (unless otherwise noted). 3 at input to sigma-delta modulator of adc. 4 guaranteed by design. 5 overall group delay will be affected by the sample rate and the external digital filtering. 6 the adc s input impedance is inversely proportional to dmclk and is approximated by: (4 10 11 )/dmclk. 7 frequency response of adc measured with input at audio reference level (the input level that produces an output level of C 10 dbm0), with 38 db preamplifier bypassed and input gain of 0 db. 8 test conditions: no load on digital inputs, analog inputs ac coupled to ground. specifications subject to change without notice. table i. afe section current summary (avdd = dvdd = 3.3 v) total current mclk conditions (max) se on comments refcap only on 1.0 0 no refout disabled refcap and refout only on 4.5 0 no all sections on 26.5 1 yes refout enabled all sections off 1.5 0 yes mclk active levels equal to 0 v and dvdd all sections off 0.1 0 no digital inputs static and equal to 0 v or dvdd the above values are in ma. mclk = 16.384 mhz; sclk = 16.384 mhz. (avdd = 3.0 v to 3.6 v; dvdd = 3.0 v to 3.6 v; dgnd = agnd = 0 v, f mclk = 16.384 mhz, f samp = 64 khz; t a = t min to t max , unless otherwise noted.)
rev. 0 C5C ad73460 specifications parameter test conditions min typ max unit dsp section v ih hi-level input voltage 1, 2 @ v dd = max 2.0 v v ih hi-level clkin voltage @ v dd = max 2.2 v v il lo-level input voltage 1, 3 @ v dd = min 0.8 v v oh hi-level output voltage 1, 4, 5 @ v dd = min, i oh = C 0.5 ma 2.4 v @ v dd = min, i oh = C 100 a 6 v dd C 0.3 v v ol lo-level output voltage 1, 4, 5 @ v dd = min, i ol = 2 ma 0.4 v i ih hi-level input current 3 @ v dd = max, v in = v dd max 10 a i il lo-level input current 3 @ v dd = max, v in = 0 v 10 a i ozh three-state leakage current 7 @ v dd = max, v in = v dd max 8 10 a i ozl three-state leakage current 7 @ v dd = max, v in = 0 v 8 10 a i dd supply current (idle) 9 @ v dd = 3.3 v t ck = 19 ns 10 14 ma t ck = 25 ns 10 12 ma t ck = 30 ns 10 10 ma i dd supply current (dynamic) 11 @ v dd = 3.3 v, t amb = 25 c t ck = 19 ns 10 54 ma t ck = 25 ns 10 43 ma t ck = 30 ns 10 37 ma c i input pin capacitance 3, 6, 12 @ v in = 2.5 v, f in = 1.0 mhz, t amb = 25 c8pf c o output pin capacitance 6, 7, 12, 13 @ v in = 2.5 v, f in = 1.0 mhz, t amb = 25 c8pf notes 1 bidirectional pins: d0 C d23, rfs0, rfs1, sclk0, sclk1, tfs0, tfs1, a1 C a13, pf0 C pf7. 2 input only pins: reset , br , dr0, dr1, pwd . 3 input only pins: clkin, reset , br , dr0, dr1, pwd . 4 output pins: bg , pms , dms , bms , ioms , cms , rd , wr , pwdack , a0, dt0, dt1, clkout, fl2 C 0, bgh . 5 although specified for ttl outputs, all ad73460 outputs are cmos-compatible and will drive to v dd and gnd, assuming no dc loads. 6 guaranteed but not tested. 7 three-statable pins: a0 C a13, d0 C d23, pms , dms , bms , ioms , cms , rd , wr , dt0, dt1, sclk0, sclk1, tfs0, tfs1, rfs0, rfs1, pf0 C pf7. 8 0 v on br . 9 idle refers to ad73460 state of operation during execution of idle instruction. deasserted pins are driven to either v dd or gnd. 10 v in = 0 v and 3 v. for typical figures for supply currents, refer to power dissipation section. 11 i dd measurement taken with all instructions executing from internal memory. 50% of the instructions are multifunction (types 1, 4, 5, 12, 13, 14), 30% are type 2 and type 6, and 20% are idle instructions. 12 applies to pbga package type. 13 output pin capacitance is the capacitive load for any three-stated output pin. specifications subject to change without notice. (avdd = 3.0 v to 3.6 v; dvdd = 3.0 v to 3.6 v; dgnd = agnd = 0 v, f mclk = 16.384 mhz, f samp = 64 khz; t a = t min to t max , unless otherwise noted.)
rev. 0 ad73460 C6C caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the ad73460 features proprietary esd protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality. warning! esd sensitive device absolute maximum ratings * (t a = 25 c unless otherwise noted) avdd, dvdd to gnd . . . . . . . . . . . . . . . C 0.3 v to +4.6 v agnd to dgnd . . . . . . . . . . . . . . . . . . . . C 0.3 v to +0.3 v digital i/o voltage to dgnd . . . . . C 0.3 v to dvdd + 0.3 v analog i/o voltage to agnd . . . . . C 0.3 v to avdd + 0.3 v operating temperature range industrial (b version) . . . . . . . . . . . . . . . C 20 c to +85 c storage temperature range . . . . . . . . . . . . C 20 c to +125 c maximum junction temperature . . . . . . . . . . . . . . . . 150 c pbga, ja thermal impedance . . . . . . . . . . . . . . . . . 25 c/w reflow soldering maximum temperature . . . . . . . . . . . . . . . . . . . . . . 225 c time at maximum temperature . . . . . . . . . . . . . . . 15 sec * stresses above those listed under absolute maximum ratings may cause perma- nent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. ordering guide temperature package package model range description options ad73460bb-80 C 20 c to +85 c 119-ball plastic grid array b-119 AD73460BB-40 C 20 c to +85 c 119-ball plastic grid array b-119 timing characteristics C afe section 1 limit at parameter t a = C 20 c to +85 c unit description clock signals see figure 1 t 1 61 ns min amclk period t 2 24.4 ns min amclk width high t 3 24.4 ns min amclk width low serial port see figures 3 and 4 t 4 t 1 ns min sclk period (sclk = amclk) t 5 0.4 t 1 ns min sclk width high t 6 0.4 t 1 ns min sclk width low t 7 20 ns min sdi/sdifs setup before sclk low t 8 0 ns min sdi/sdifs hold after sclk low t 9 10 ns max sdofs delay from sclk high t 10 10 ns max sdofs hold after sclk high t 11 10 ns max sdo hold after sclk high t 12 10 ns max sdo delay from sclk high t 13 30 ns max sclk delay from amclk notes 1 for details of the dsp section timing, please refer to the adsp-2185l data sheet and the adsp-2100 family user? manual, third edition. specifications subject to change without notice. (avdd = 3 v to 3.6 v; dvdd = 3 v to 3.6 v; agnd = dgnd = 0 v; t a = t mln to t max , unless otherwise noted.)
ad73460 C7C rev. 0 pbga ball configurations pbga ball pbga ball pbga ball pbga ball number name number name number name number name a1 irqe / pf4 e3 rfs0 j5 d22 n7 d13 a2 dms e4 a3/iad2 j6 d21 p1 ebr a3 vdd(int) e5 a2/iad1 j7 d20 p2 d0/iad13 a4 clkin e6 a1/iad0 k1 elout p3 dvdd a5 a11/iad10 e7 a0 k2 elin p4 dgnd a6 a7/iad6 f1 dr0 k3 eint p5 areset a7 a4/iad3 f2 sclk0 k4 d19 p6 sclk2 b1 irql0 / pf5 f3 dt1 k5 d18 p7 mclk b2 pms f4 pwdack k6 d17 r1 sdo b3 wr f5 bgh k7 d16 r2 sdofs b4 xtal f6 mode a/ pf0 l1 bg r3 sdifs b5 a12/iad11 f7 mode b/ pf1 l2 d3/ iack r4 sdi b6 a8/iad7 g1 tfs1 l3 d5/ial r5 se b7 a5/iad4 g2 rfs1 l4 d8 r6 refcap c1 irql1 / pf6 g3 dr1 l5 d9 r7 refout c2 ioms g4 gnd l6 d12 t1 vinn2 c3 rd g5 pwd l7 d15 t2 vinp2 c4 vdd(ext) g6 vdd(ext) m1 ebg t3 vinn1 c5 a13/iad12 g7 mode c/ pf2 m2 d2/iad15 t4 vinp1 c6 a9/iad8 h1 sclk1 m3 d4/ is t5 vinn3 c7 gnd h2 ereset m4 d7/ iwr t6 vinp3 d1 irq2 / pf7 h3 reset m5 vdd(ext) t7 vinn4 d2 cms h4 pf3 m6 d11 u1 agnd d3 bms h5 fl0 m7 d14 u2 avdd d4 clkout h6 fl1 n1 br u3 vinp6 d5 gnd h7 fl2 n2 d1/iad14 u4 vinn6 d6 a10/iad9 j1 ems n3 vdd(int) u5 vinp5 d7 a6/iad5 j2 ee n4 d6/ ird u6 vinn5 e1 dt0 j3 eclk n5 gnd u7 vinp4 e2 tfs0 j4 d23 n6 d10 pbga ball configuration a b c d e f g h j k l m n p r t u 1234567 a b c d e f g h j k l m n p r t u 1234567
rev. 0 ad73460 C8C pin function descriptions 1 mnemonic function vinp1 analog input to the positive terminal of input channel 1. vinn1 analog input to the negative terminal of input channel 1. vinp2 analog input to the positive terminal of input channel 2. vinn2 analog input to the negative terminal of input channel 2. vinp3 analog input to the positive terminal of input channel 3. vinn3 analog input to the negative terminal of input channel 3. vinp4 analog input to the positive terminal of input channel 4. vinn4 analog input to the negative terminal of input channel 4. vinp5 analog input to the positive terminal of input channel 5. vinn5 analog input to the negative terminal of input channel 5. vinp6 analog input to the positive terminal of input channel 6. vinn6 analog input to the negative terminal of input channel 6. refout buffered reference output, which has a nominal value of 1.25 v. refcap a bypass capacitor to agnd2 of 0.1 f is required for the on-chip reference. the capacitor should be fixed to this pin. this pin can be overdriven by an external reference if required. avdd analog power supply connection agnd analog ground/substrate connection dgnd digital ground/substrate connection dvdd digital power supply connection areset active low reset signal. this input resets the analog front end of the ad73460, resetting the control registers and clearing the digital circuitry. sclk2 output serial clock whose rate determines the serial transfer rate to/from the afe. it is used to clock data or control information to and from the serial port (sport2). the frequency of sclk is equal to the frequency of the master clock (mclk) divided by an integer number this integer number being the product of the external master clock rate divider and the serial clock rate divider. mclk master clock input of the analog front end. mclk is driven from an external clock signal. sdo serial data output of the ad73460. both data and control information may be output on this pin and are clocked on the positive edge of sclk2. sdo is in three-state when no information is being transmitted and when se is low. sdofs framing signal output for sdo serial transfers. the frame sync is one bit wide and it is active one sclk period before the first bit (msb) of each output word. sdofs is referenced to the positive edge of sclk2. sdofs is in three-state when se is low. sdifs framing signal input for sdi serial transfers. the frame sync is one bit wide and it is valid one sclk period be fore the first bit (msb) of each input word. sdifs is sampled on the negative edge of sclk2 and is ignored when se is low. sdi serial data input of the ad73460. both data and control information may be input on this pin and are clocked on the negative edge of sclk2. sdi is ignored when se is low. se sport enable. asynchronous input enable pin for the sport. when se is set low by the dsp, the output pins of the sport are three-stated and the input pins are ignored. sclk2 is also disabled internally in order to decrease power dissipation. when se is brought high, the control and data registers of the sport are at their original values (before se was brought low); however, the timing counters and other internal registers are at their reset values. reset (input) processor reset input br (input) bus request input bg (output) bus grant output bgh (output) bus grant hung output dms (output) data memory select output pms (output) program memory select output ioms (output) memory select output bms (output) byte memory select output cms (output) combined memory select output rd (output) memory read enable output
ad73460 C9C rev. 0 pin function descriptions 1 (continued) mnemonic function wr (output) memory write enable output irq2 / (input) edge- or level-sensitive interrupt pf7 (input/output) request. 2 programmable i/o pin irql0/ (input) level-sensitive interrupt requests 2 pf6 (input/output) programmable i/o pin irql1/ (input) level-sensitive interrupt requests 2 pf5 (input/output) programmable i/o pin irqe / (input) edge-sensitive interrupt requests 2 pf4 (input/output) programmable i/o pin mode d/ (input) mode select input checked only during reset pf3 (input/output) programmable i/o pin during normal operation mode c/ (input) mode select input checked only during reset pf2 (input/output) programmable i/o pin during normal operation mode b/ (input) mode select input checked only during reset pf1 (input/output) programmable i/o pin during normal operation mode a/ (input) mode select input checked only during reset pf0 (input/output) programmable i/o pin during normal operation clkin, (inputs) clock or quartz crystal input xtal clkout (output) processor clock output sport0 (inputs/outputs) serial port i/o pins sport1 (inputs/outputs) serial port i/o pins irq1 :0 (inputs) edge- or level-sensitive interrupts, fi (input) flag in 3 fo (output) flag out 3 pwd (input) power-down control input pwdack (output) power-down control output fl0, fl1, (outputs) output flags fl2 a13 to a0 (output) address output pins for program, data, byte, and i/o space d23 to d0 (input/output) data i/o pins for program, data, byte, and i/o space vdd and power and ground gnd ez-ice port (inputs/outputs) for emulation use ereset ems ee eclk elout elin eint ebr ebg notes 1 refer to the adsp-2185l data sheet for a detailed description of the dsp pins. 2 interrupt/flag pins retain both functions concurrently. if imask is set to enable the corresponding interrupts, then the dsp wi ll vector to the appropriate interrupt vector address when the pin is asserted, either by external devices, or set as a programmable flag. 3 sport configuration determined by the dsp system control register. software configurable.
rev. 0 ad73460 C10C architecture overview the ad73460 instruction set provides flexible data moves and multifunction (one or two data moves with a computation) instruc- tions. every instructions can be executed in a single processor cycle. the ad73460 assembly language uses an algebraic syntax for ease of coding and readability. a comprehensive set of devel- opment tools supports program development. serial port sport 2 ref adc3 analog front end section adc1 adc2 adc4 adc5 adc6 external address bus serial ports sport 0 shifter mac alu arithmetic units memory programmable i/o and flags byte dma controller timer power-down control program sequencer dag 2 data address generators program memory address data memory address program memory data data memory data dag 1 16k dm (optional 8k) 16k pm (optional 8k) external data bus full memory mode sport 1 ad73460 adsp-2100 base architecture figure 1. functional block diagram figure 1 is an overall block diagram of the ad73460. the pro- cessor section contains three independent computational units: the alu, the multiplier/accumulator (mac) and the shifter. the computational units process 16-bit data directly and have provi- sions to support multiprecision computations. the alu performs a standard set of arithmetic and logic operations; division primi- tives are also supported. the mac performs single-cycle multiply, multiply/add and multiply/subtract operations with 40 bits of accumulation. the shifter performs logical and arithmetic shifts, normalization, denormalization, and d erive exponent operations. the internal result (r) bus connects the computational units so that the output of any unit may be the input of any unit on the next cycle. a powerful program sequencer and two dedicated data address genera tors ensure efficient de livery of operands to these compu- tational units. the sequencer supports conditional jumps, sub routine calls and returns in a single cycle. with internal loop counters and loop stacks, the ad73460 executes looped code with zero overhead; no explicit jump instructions are required to maintain loops. two data address generators (dags) provide addresses for simultaneous dual operand fetches (from data memory and program memory). each dag maintains and updates four address pointers. whenever the pointer is used to access data (indirect addressing), it is post-modified by the value of one of four possible modify registers. a length value may be associated with each pointer to implement automatic modulo addressing for circular buffers. the two address buses (pma and dma) share a single external address bus, allowing memory to be expanded off-chip, and the two data buses (pmd and dmd) share a single external data bus. byte memory space and i/o memory space also share the external buses. an interface to low-cost byte-wide memory is provided by the byte dma port (bdma port). the bdma port is bidirectional and can directly address up to four megabytes of external ram or rom for off-chip storage of program overlays or data tables. the ad73460 can respond to eleven interrupts. there can be up to six external interrupts (one edge-sensitive, two level-sensitive and three configurable) and seven internal interrupts generated by the timer, the serial ports (sports), the byte dma port and the power-down circuitry. there is also a master reset signal. the two serial ports provide a complete synchronous serial interface with optional companding in hardware and a wide variety of framed or frameless data transmit and receive modes of operation. analog front end the analog front end (afe) of the ad73460 is configured as a separate block that is normally connected to either sport0 or sport1 of the dsp section. as it is not hardwired to either sport users have total flexibility in how they wish to allocate system resources to support the afe. it is also possible to further expand the number of analog input channels connected to the sport by cascading an ad73360 device external to the ad73460. the afe is configured as six input channels. it comprises six independent encoder channels each featuring signal condition- ing, programmable gain amplifier, sigma-delta a/d convertor and decimator sections. each of these sections is described in further detail below. all channels share a common internal reference whose nominal value is 1.25 v. figure 2 shows a block diagram of the afe section of the ad73460. it shows six input channels along with a common reference. communication to all channels is handled by the sport2 block which interfaces to either sport0 or sport1 of the dsp section.
ad73460 C11C rev. 0 vinn1 vinp1 analog - modulator sdi sdifs sclk2 refcap refout se areset sdofs sdo amclk vinn2 vinp2 vinn3 vinp3 vinn4 vinp4 vinn5 vinp5 vinn6 vinp6 afe section signal conditioning 0/38db pga decimator serial i/o port signal conditioning 0/38db pga decimator signal conditioning 0/38db pga decimator signal conditioning 0/38db pga decimator signal conditioning 0/38db pga decimator signal conditioning 0/38db pga decimator reference analog - modulator analog - modulator analog - modulator analog - modulator analog - modulator ad73460 figure 2. functional block diagram of analog front end table ii. pga settings for the encoder channel ixgs2 ixgs1 ixgs0 gain (db) 000 0 001 6 010 12 011 18 100 20 101 26 110 32 111 38 adc each channel has its own adc consisting of an analog sigma- delta modulator and a digital antialiasing decimation filter. the sigma-delta modulator noise-shapes the signal and produces 1-bit samples at a dmclk/8 rate. this bitstream, representing the analog input signal, is input to the antialiasing decimation filter. the decimation filter reduces the sample rate and increases the resolution. functional description afe encoder channel each encoder channel consists of a signal conditioner, a switched capac itor pga, and a sigma-delta analog-to-digital converter (adc). an on-board digital filter, which forms part of the sigma-delta adc, also performs critical system-level filtering. due to the high level of oversampling, the input antialias require- ments are reduced such that a simple single pole rc stage is sufficient to give adequate attenuation in the band of interest. signal conditioner each analog channel has an independent signal conditioning block. this allows the analog input to be configured by the user depending on whether differential or single-ended mode is used. programmable gain amplifier each encoder section s analog front end comprises a switched capacitor pga that also forms part of the sigma-delta modulator. the sc sampling frequency is dmclk/8. the pga, whose programmable gain settings are shown in table ii, may be used to increase the signal level applied to the adc from low output sources such as microphones, and can be used to avoid placing external amplifiers in the circuit. the input signal level to the sigma-delta modulator should not exceed the maximum input voltage permitted. the pga gain is set by bits igs0, igs1, and igs2 in control registers d, e, and f.
rev. 0 ad73460 C12C analog sigma-delta modulator the ad73460 input channels employ a sigma-delta conversion technique, which provides a high resolution 16-bit output with system filtering being implemented on-chip. sigma-delta converters employ a technique known as over- sampling, w here the sampling rate is many times the highest frequency of interest. in the case of the ad73460, the initial sampling rate of the sigma-delta modulator is dmclk/8. the main effect of oversampling is that the quantization noise is spread over a very wide bandwidth, up to f s /2 = dmclk/16 (figure 3a). this means that the noise in the band of interest is much reduced. another complementary feature of sigma-delta converters is the use of a technique called noise-shaping. this technique has the effect of pushing the noise from the band of interest to an out-of-band position (figure 3b). the combina- tion of these techniques, followed by the application of a digital filter, reduces the noise in band sufficiently to ensure good dynamic performance from the part (figure 3c). band of interest f s /2 dmclk/16 a. f s /2 dmclk/16 noise-shaping b. band of interest f s /2 dmclk/16 digital filter band of interest c. figure 3. sigma-delta noise reduction figure 4 shows the various stages of filtering that are employed in a typical ad73460 application. in figure 4a we see the trans- fer function of the external analog antialias filter. even though it is a single rc pole, its cutoff frequency is sufficiently far away from the initial sampling frequency (dmclk /8) that it takes care of any signals that could be aliased by the sampling frequency. this also shows the major difference between the initial over- sampling rate and the bandwidth of interest. in figure 4b, the signal and noise-shaping responses of the sigma-delta modulator are shown. the signal response provides further rejection of any high frequency signals while the noise-shaping will push the inher- ent quantization noise to an out-of-band position. the detail of figure 4c shows the response of the digital decimation filter (sinc-cubed response) with nulls every multiple of dmclk /256, which is the decimation filter update rate. the final detail in figure 4d shows the application of a final antialias filter in the dsp engine. this has the advantage of being implemented ac cord- ing to the user s requirements and available mips. the filtering in figures 4a through 4c is implemented in the ad73 460. f b = 4khz f sinit = dmclk/8 a. analog antialias filter transfer function f b = 4khz f sinit = dmclk/8 noise transfer function signal transfer function b. analog sigma-delta modulator transfer function f b = 4khz f sinter = dmclk/256 c. digital decimator transfer function f b = 4khz f sinter = dmclk/256 f sfinal = 8khz d. final filter lpf (hpf) transfer function figure 4. dc frequency responses decimation filter the digital filter used in the ad73460 carries out two important functions. firstly, it removes the out-of-band quantization noise, which is shaped by the analog modulator and secondly, it deci- mates the high frequency bitstream to a lower rate 15-bit word. the antialiasing decimation filter is a sinc-cubed digital filter that reduces the sampling rate from dmclk/8 to dmclk/256, and increases the resolution from a single bit to 15 bits. its z transform is given as: [(1 C z C 32 )/(1 C z C 1 )] 3 . this ensures a mini- mal group delay of 25 s.
ad73460 C13C rev. 0 adc coding the adc coding scheme is in two s complement format (see figure 5). the output words are formed by the decimation filter, which grows the word length from the single-bit output of the sigma-delta modulator to a 15-bit word, which is the final output of the adc block. in 16-bit data mode this value is left shifted with the lsb being set to 0. for input values equal to or greater than positive full scale however, the output word is set at 0x7fff, which has the lsb set to 1. in mixed control/data mode, the resolution is fixed at 15 bits, with the msb of the 16-bit transfer being used as a flag bit to indicate either control or data in the frame. v ref + (v ref 0.32875) v ref v ref ?(v ref 0.32875) 10...00 00...00 01...11 adc code differential analog input v inn v inp v ref + (v ref 0.6575) v ref ?(v ref 0.6575) 10...00 00...00 01...11 adc code single-ended analog input v inp v inn figure 5. adc transfer function voltage reference the ad73460 contains an internal bandgap reference that provides a low noise, temperature-compensated reference to the adcs. the reference has a nominal value of 1.25 v and is avail- able on the refcap pin. a buffered version of the reference is available on the refout pin and can be used to bias external analog circuitry if required. the reference output (refout) can be enabled by setting the ru bit (crc:6) in control register c. it is possible to overdrive the internal reference by connecting an external reference to the refcap pin. this may be required when a different value of reference or better temperature coeffi- cient is required. the current sink and source capabilities of the refcap pin must be taken into consideration when overdriv- ing the reference. when a lower value of external reference is required it must have sufficient current sink capability to over- ride the current source capabilities of the refcap pin. when a higher value of external reference is required it can usually be connected directly to the refcap pin as the pin can typically only sink 0.25 ma before its value changes. figure 6 shows a plot of refcap voltage versus current. note that the negative values indicate that the external reference is sinking current to provide the required reference voltage. afe serial port (sport2) the afe section communicates with dsp via the bidirectional synchronous serial port (sport2) which interfaces to either sport0 or sport1 of the dsp section. sport2 is used to transmit and receive digital data and control information. an refcap v 4.5 1.00 current ma 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.5 1.10 1.20 1.30 1.40 1.50 figure 6. refcap voltage vs. current additional external afe can be cascaded to the internal afe (up to a limit of seven) to provide additional input channels if required. in both transmit and receive modes, data is transferred at the serial clock (sclk2) rate with the msb being transferred first. communication between the afe section and dsp section must always be initiated by the afe section (afe is in master mode, dsp is in slave mode). this ensures that there is no collision between input data and output samples. sport2 overview sport2 is a flexible, full-duplex, synchronous serial port whose protocol has been designed to allow an additional afe to be connected in cascade to the dsp section. it has a very flexible architecture that can be configured by programming two of the internal control registers in each afe block. sport2 has three distinct modes of operat ion: control mode, data mode, and mixed control/data mode. note: as each afe has its own sport section, the register settings in each must be programmed. the registers that control sport and sample rate operation (cra and crb) must be programmed with the same values to ensure correct operation. in control mode (cra:0 = 0), the device s internal configura- tion can be programmed by writing to the eight internal control registers. in this mode, control information can be written to or read from the afe. in data mode (cra:0 = 1), any information that is sent to the afe is ignored, while the encoder section (adc) data is read from the device. in this mode, only adc data is read from the device. mixed mode (cra:0 = 1 and cra:1 = 1) allows the user to send control information and receive either control information or adc data. this is achieved by using the msb of the 16-bit frame as a flag bit. mixed mode reduces the resolution to 15 bits with the msb being used to indicate whether the information in the 16-bit frame is control information or adc data. sport2 features a single 16-bit serial register that is used for both input and output data transfers. as the input and output data must share the same register, some precautions must be observed. the primary precaution is that no information must be written to sport2 without reference to an output sample event, which is when the serial register will be overwritten with the latest adc sample word. once sport2 starts to output the latest adc word, it is safe for the dsp to write new control
rev. 0 ad73460 C14C words to the afe. in certain configurations, data can be written to the device to coincide with the output sample being shifted out of the serial register see section on interfacing devices. the serial clock rate (crb:2 C 3) defines how many 16-bit words can be written to a device before the next output sample event will happen. the sport2 block diagram, shown in figure 7, details the blocks associated with afe including the eight control registers (a C h), external amclk to internal dmclk divider and serial clock divider. the divider rates are controlled by the setting of control register b. the afe features a master clock divider that allows users the flexibility of dividing externally available high frequency dsp clocks to generate a lower frequency master clock internally in the afe, which may be more suitable for either serial transfer or sampling rate requirements. the master clock divider has five divider options ( 1 default condition, 2, 3, 4, 5) that are set by loading the master clock divider field in register b with the appropriate code (see table viii). once the internal device master clock (dmclk) has been set using the master clock divider, the sample rate and serial clock set- tings are derived from dmclk. mclk divider amclk (external) se areset sdifs sdi serial port (sport) serial register sclk2 control register b control register c control register d control register e control register a 3 8 8 8 8 8 8 2 dmclk (internal) sdofs sdo control register f control register g control register h sclk divider figure 7. sport block diagram sport2 can work at four different serial clock (sclk) rates: chosen from dmclk, dmclk/2, dmclk/4, or dmclk/8, where dmclk is the internal or device master clock resulting from the external or pin master clock being divided by the mas- ter clock divider. care should be taken when selecting master clock, serial clock, and sample rate divider settings to ensure that there is sufficient time to read all the data from the afe before the next sample interval. sport register maps there are eight control registers for the afe, each eight bits wide. table vi shows the control register map for the afe. the first two control registers, cra and crb, are reserved for controlling sport2. they hold settings for parameters such as bit rate, internal master clock rate, and device count. if multiple afes are cascaded, registers cra and crb on both devices must be programmed with the same setting to ensure correct operation. the other six registers, crc through crh, are used to hold control settings for the reference, power control, adc channel, and pga sections of the device. it is not necessary that the contents of crc through crh on each afe are similar. control registers are w ritten to on the negative edge of sclk2. master clock divider the afe features a programmable master clock divider that allows the user to reduce an externally available master clock, at pin amclk, by one of the ratios 1, 2, 3, 4, or 5 to produce an internal master clock signal (dmclk) that is used to calculate the sampling and serial clock rates. the master clock divider is programmable by setting crb:4 C 6. table iii shows the division ratio corresponding to the various bit settings. the default divider ratio is divide-by-one. table iii. dmclk (internal) rate divider settings mcd2 mcd1 mcd0 dmclk rate 000amclk 0 0 1 amclk/2 0 1 0 amclk/3 0 1 1 amclk/4 1 0 0 amclk/5 101amclk 110amclk 111amclk serial clock rate divider the afe features a programmable serial clock divider that allows users to match the serial clock (sclk2) rate of the data to that of the dsp. the maximum sclk2 rate available is dmclk and the other available rates are: dmclk/2, dmclk/4 and dmclk/8. the slowest rate (dmclk/8) is the default sclk2 rate. the serial clock divider is programmable by setting bits crb:2 C 3. table iv shows the serial clock rate corresponding to the various bit settings. table iv. sclk rate divider settings scd1 scd0 sclk2 rate 0 0 dmclk/8 0 1 dmclk/4 1 0 dmclk/2 1 1 dmclk decimation rate divider the afe features a programmable decimation rate divider that allows users flexibility in matching the afe s adc sample rates to the needs of the dsp software. the maximum sample rate available is dmclk/256 and the other available rates are: dmclk/512, dmclk/1024 and dmclk/2048. the slowest rate (dmclk/2048) is the default sample rate. the sample rate divider is programmable by setting bits crb:0 C 1. table v shows the sample rate corresponding to the various bit settings. table v. decimation rate divider settings dr1 dr0 sample rate 0 0 dmclk/2048 0 1 dmclk/1024 1 0 dmclk/512 1 1 dmclk/256
ad73460 C15C rev. 0 table vi. control register map address (binary) name description type width reset setting (hex) 000 cra control register a r/ w 8 0x00 001 crb control register b r/ w 8 0x00 010 crc control register c r/ w 8 0x00 011 crd control register d r/ w 8 0x00 100 cre control register e r/ w 8 0x00 101 crf control register f r/ w 8 0x00 110 crg control register g r/ w 8 0x00 111 crh control register h r/ w 8 0x00 table vii. control word description 1514131211109 8 76543210 c/ d r/ w device address register address register data control frame description bit 15 control/ data when set high, it signifies a control word in program or mixed program/data modes. when set low, it signifies an invalid control word in program mode. bit 14 read/ write when set low, it tells the device that the data field is to be written to the register selected by the register field setting provided the address field is zero. when set high, it tells the device that the selected register is to be written to the data field in the serial register and that the new control w ord is to be output from the device via the serial output. bits 13 C 11 device address this 3-bit field holds the address information. only when this field is zero is a device se- lected. if the address is not zero, it is decremented and the control word is passed out of the device via the serial output. bits 10 C 8 register address this 3-bit field is used to select one of the eight control registers on the ad73460. bits 7 C 0 register data this 8-bit field holds the data that is to be written to or read from the selected register pro- vided the address field is zero. control register a table viii. control register a description bit name description 0 data/ pgm operating mode (0 = program; 1 = data mode) 1 mm mixed mode (0 = off; 1 = enabled) 2 reserved must be programmed to zero (0) 3 slb sport loop-back mode (0 = off; 1 = enabled) 4 dc0 device count (bit 0) 5 dc1 device count (bit 1) 6 dc2 device count (bit 2) 7 reset software reset (0 = off; 1 = initiates reset) 7 654321 0 reset dc2 dc1 dc0 slb res mm data/ pgm
rev. 0 ad73460 C16C table ix. control register b description 76543210 cee mcd2 mcd1 mcd0 scd1 scd0 dr1 dr0 bit name description 0 dr0 decimation rate (bit 0) 1 dr1 decimation rate (bit 1) 2 scd0 serial clock divider (bit 0) 3 scd1 serial clock divider (bit 1) 4 mcd0 master clock divider (bit 0) 5 mcd1 master clock divider (bit 1) 6 mcd2 master clock divider (bit 2) 7 cee control echo enable (0 = off; 1 = enabled) table x. control register c description 76543210 res ru puref res res res res gpu bit name description 0 gpu global power-up device (0 = power down; 1 = power up) 1 reserved must be programmed to zero (0) 2 reserved must be programmed to zero (0) 3 reserved must be programmed to zero (0) 4 reserved must be programmed to zero (0) 5 puref ref power (0 = power down; 1 = power up) 6 ru refout use (0 = disable refout; 1 = en able refout) 7 reserved must be programmed to zero (0) table xi. control register d description 76543210 pui2 i2gs2 i2gs1 i2gs0 pui1 i1gs2 i1gs1 i1gs0 bit name description 0 i1gs0 adc1: input gain select (bit 0) 1 i1gs1 adc1: input gain select (bit 1) 2 i1gs2 adc1: input gain select (bit 2) 3 pui1 power control (adc1): 1 = on, 0 = off 4 i2gs0 adc2: input gain select (bit 0) 5 i2gs1 adc2: input gain select (bit 1) 6 i2gs2 adc2: input gain select (bit 2) 7 pui2 power control (adc2): 1 = on, 0 = off control register b control register c control register d
ad73460 C17C rev. 0 table xii. control register e description 76543210 pui4 i4gs2 i4gs1 i4gs0 pui3 i3gs2 i3gs1 i3gs0 bit name description 0 i3gs0 adc3: input gain select (bit 0) 1 i3gs1 adc3: input gain select (bit 1) 2 i3gs2 adc3: input gain select (bit 2) 3 pui3 power control (adc3): 1 = on, 0 = off 4 i4gs0 adc4: input gain select (bit 0) 5 i4gs1 adc4: input gain select (bit 1) 6 i4gs2 adc4: input gain select (bit 2) 7 pui4 power control (adc4): 1 = on, 0 = off table xiii. control register f description 76543210 pui6 i6gs2 i6gs1 i6gs0 pui5 i5gs2 i5gs1 i5gs0 bit name description 0 i5gs0 adc5: input gain select (bit 0) 1 i5gs1 adc5: input gain select (bit 1) 2 i5gs2 adc5: input gain select (bit 2) 3 pui5 power control (adc5): 1 = on, 0 = off 4 i6gs0 adc6: input gain select (bit 0) 5 i6gs1 adc6: input gain select (bit 1) 6 i6gs2 adc6: input gain select (bit 2) 7 pui6 power control (adc6): 1 = on, 0 = off table xiv. control register g description 76543210 seen rmod ch6 ch5 ch4 ch3 ch2 ch1 bit name description 0 ch1 channel 1 select 1 ch2 channel 2 select 2 ch3 channel 3 select 3 ch4 channel 4 select 4 ch5 channel 5 select 5 ch6 channel 6 select 6 rmod reset analog modulator 7 seen enable single-ended input mode control register e control register f control register g
rev. 0 ad73460 C18C operation resetting the afe the areset pin resets all the control registers. all the afe registers are reset to zero, indicating that the default sclk2 rate ( dmclk/8) and sample rate (dmclk/2048) are at a mini- mum. as well as resetting the control registers of the afe using the areset pin, the device can be reset using the reset bit (cra:7) in control register a. both hardware and software resets require four dmclk cycles. on reset, data/ pgm (cra:0) is set to 0 (default condition) thus enabling control mode. the reset conditions ensure that the device must be programmed to the correct settings after power-up or reset. following a reset, the sdofs will be asserted approximately 2070 master (amclk) cycles after areset goes high. the data that is output following the reset and during control mode is random and contains no valid information until either data or mixed mode is set. power management the individual functional blocks of the afe can be enabled separately by programming the power control register crc. (the power management functions of the dsp section are separate and will be referred to later.) it allows certain sections to be powered down if not required, which adds to the device s flexibility in that the user need not incur the penalty of having to provide power for a certain section if it is not necessary to their design. the power control registers provide individual control settings for the major functional blocks on each analog front end unit and also a global override that allows all sections to be powered up/down by setting/clearing the bit. using this method the user could, for example, individually enable a certain section, such as the reference (crc:5), and disable all others. the glo- bal power-up (crc:0) can be used to enable all sections, but if power-down is required using the global control, the reference will still be enabled; in this case, because its individual bit is set. refer to table x for details of the settings of crc. crd C crf can be used to control the power status of individual channels allowing multiple channels to be powered down if required. operating modes three operating modes are available on the afe. they are control (program) mode, data mode, and mixed control/ data mode. the device configuration register settings can be changed only in program and mixed program/data modes. in all modes, transfers of information to or from the device occur in 16-bit packets, therefore the dsp engine s sport will be programmed for 16-bit transfers. control mode in control mode, cra:0 = 0, the user writes to the control registers to set up the device for desired operation sport2 operation, cascade length, power management, input/output gain, etc. in this mode, the 16-bit information packet sent to the device by the dsp is interpreted as a control word whose format is shown in table vii. in this mode, the user m=ust address the device to be programmed using the address field of the control word. this field is read by the device and if it is zero (000 bin), the device recognizes the word as being addressed to it. if the address field is not zero, it is then decremented and the control word is passed out of the device either to the next device in a cascade or back to the dsp. this 3-bit address format allows the user to uniquely address any device in a cascade. if the afe is used in a standalone configuration connected to the dsp, the device address corre- sponds to 0. following reset, when the se pin is enabled, the afe responds by raising the sdofs pin to indicate that an output sample event has occurred. control words can be written to the device to coincide with the data being sent out of sport2, as shown in figure 9 (directly coupled), or they can lag the output words by a time interval that should not exceed the sample interval (indirectly coupled). refer to the digital interface section for more information. after reset, output frame sync pulses will occur at a slower default sample rate, which is dmclk/2048, until control register b is programmed, after which the sdofs will be pulsed at the selected rate. while the afe is in control mode, the data output by the device is random and should not be interpreted as adc data. table xv. control register h description 76543210 inv tme ch6 ch5 ch4 ch3 ch2 ch1 bit name description 0 ch1 channel 1 select 1 ch2 channel 2 select 2 ch3 channel 3 select 3 ch4 channel 4 select 4 ch5 channel 5 select 5 ch6 channel 6 select 6 tme test mode enable 7 inv enable invert channel mode control register h
ad73460 C19C rev. 0 data mode once the device has been configured by programming the cor- rect settings to the various control registers, the device may exit program mode and enter data mode. this is done by program- ming the data/ pgm (cra:0) bit to 1 and mm (cra:1) to 0. once the device is in data mode, the input data is ignored. when the device is in normal data mode (i.e., mixed mode disabled), it must receive a hardware reset to reprogram any of the control register settings. mixed program/data mode this mode allows the user to send control words to the device while receiving adc words. this permits adaptive control of the device whereby control of the input gains can be affected by reprogramming the control registers. the standard data frame remains 16 bits, but now the msb is used as a flag bit to indi- cate that the remaining 15 bits of the frame represent control information. mixed mode is enabled by setting the mm bit (cra:1) to 1 and the data/ pgm bit (cra:0) to 1. in the case where control setting changes will be required during normal operation, this mode allows the ability to load control informa- tion with the slight inconvenience of formatting the data. note that the output samples from the adc will also have the msb set to zero to indicate it is a data word. channel selection the adc channels of the ad73460 can be powered up or down individually by programming the puix bit of registers crd to crf. if the ad73460 is being used in mixed data/control m ode, individual channels may be powered up or down as the program requires. in data mode, the number of channels selected while the ad73460 was in program mode is fixed and cannot be altered without resetting and reprogramming the ad73460. in all cases adc channel 1 must be powered up as the frame sync pulse generated by this channel defines the start of a new sample interval. interfacing the afe section sport (sport2) can be interfaced to either sport0 or sport1 of the dsp section. both serial input and output data use an accompanying frame synchronization signal that is active high one clock cycle before the start of the 16-bit word or during the last bit of the previous word if transmission is continuous. the serial clock (sclk) is an output from the afe and is used to define the serial transfer rate to the dsp s tx and rx ports. two primary configurations can be used: the first is shown in figure 8 where the dsp s tx data, tx frame sync, rx data and rx frame sync are connected to the ad73460 s sdi, sdifs, sdo, and sdofs, respectively. this configuration, referred to as indirectly coupled or nonframe sync loop-back, has the effect of decoupling the transmission of input data from the receipt of output data. when programming the dsp serial port for this configuration, it is necessary to set the rx frame sync as an input to the dsp and the tx frame sync as an output generated by the dsp. this configuration is most useful when operating in mixed mode, as the dsp has the ability to decide how many words can be sent to the afe(s). this means that full control can be implemented over the device configuration in a given s ample interval. the second configuration (shown in figure 9) has the dsp s tx data and rx data connected to the afe s sdi and sdo, respectively, while the dsp s tx and rx frame syncs are connected to the ad73460 s sdifs and sdofs. in this configuration, referred to as directly coupled or frame sync loop-back, the frame sync signals are connected together and the input data to the afe is forced to be synchronous with the output data from the afe. the dsp must be programmed so that both the tx and rx frame syncs are inputs as the afe s sdofs will be input to both. this configuration guarantees that input and output events occur simulta neously and is the simplest configuration for operation in normal d ata mode. note that when programming the afe in this configuration it is advisable to preload the transmit register with the first control word to be sent before the afe is taken out of reset. this ensures that this word will be transmitted to coincide with the first output w ord from the device(s). tfs(0/1) dt(0/1) sclk(0/1) dr(0/1) rfs(0/1) dsp section afe section sdifs sdi sclk sdo sofs figure 8. indirectly coupled or nonframe sync loop-back configuration tfs(0/1) dt(0/1) sclk(0/1) dr(0/1) rfs(0/1) dsp section afe section sdifs sdi sclk sdo sdofs figure 9. directly coupled or frame sync loop-back configuration cascade operation the ad73460 has been designed to support cascading of an external afe from either sport0 or sp ort1. the sport2 interface protocol has been designed so that device addressing is built into the packet of information sent to the device. this allows the cascade to be formed with no extra hardware overhead for control signals or addressing. a cascade can be formed in either of the two modes previously discussed. there may be some restrictions in cascade operation due to the number of devices configured in the cascade and the serial clock rate chosen. the formula below gives an indication of whether the combination of sample rate, serial clock, and number of devices can be successfully cascaded. this assumes a directly coupled frame sync arrangement as shown in figure 9 and does not take any interrupt latency into account. 16 11617 f device count sclk s ?+ [(( ) ) ] when using the indirectly coupled frame sync configuration in cascaded operation it is necessary to be aware of the restrictions in sending control word data to all devices in the cascade. the user should ensure that there is sufficient time for all the control words to be sent between reading the last adc sample and the start of the next sample period.
rev. 0 ad73460 C20C in cascade mode, both devices must know the number of devices in the cascade to be able to output data at the correct time. control register a contains a 3-bit field (dc0 C 2) that is pro- grammed by the dsp during the programming phase. the default condition is that the field contains 000b, which is equiva- lent to a single device in cascade (see table xvi). however, for cascade operation this field must contain a binary value that is one less than the number of devices in the cascade. with a cascade, each device takes a turn to send an adc result to the dsp. for example, in a cascade of two devices the data will be output as device 2-channel 1, device 1-channel 1, device 2-channel 2, device 1-channel 2 etc. when the first device in the cascade has transmitted its channel data there is an additional sclk period during which the last device asserts its sdofs as it begins its transmission of the next channel. this will not cause a problem for most dsps as they count clock edges after a frame sync and hence the extra bit will be ignored. when two devices are connected in cascade there are also restrictions concerning which adc channels can be powered up. in all cases the cascaded devices must all have the same channels powered up (i.e., for a cascade requiring channels 1 and 2 on device 1 and channel 5 on device 2, c hannels 1, 2, and 5 must be powered up on both devices to ensure correct operation). table xvi. device count settings dc2 dc1 dc0 cascade length 00 01 00 12 01 03 01 14 10 05 10 16 11 07 11 18 functional description dsp the ad73460 instruction set provides flexible data moves and multifunction (one or two data moves with a computation) instruc- tions. every instruction can be executed in a single processor cycle. the ad73460 assembly language uses an algebraic syntax for ease of coding and readability. a comprehensive set of development tools supports program development. figure 10 is an overall block diagram of the ad73460. the processor contains three independent computational units: the alu, the multiplier/accumulator (mac), and the shifter. the computational units process 16-bit data directly and have provi- sions to support multiprecision computations. the alu performs a standard set of arithmetic and logic operations; d ivision primi- tives are also supported. the mac performs single- cycle multiply, multiply/add, and multiply/subtract operations with 40 bits of accumulation. the shifter performs logical and a rithmetic shifts, normalization, denormalization, and derive exponent operations. the shifter can be used to efficiently implement numeric format control including multiword and block floating-point representations. the internal result (r) bus connects the computational units so that the output of any unit may be the input of any unit on the next cycle. a powerful program sequencer and two dedicated data address generators ensure efficient delivery of operands to these com- putational units. the sequencer supports conditional jumps, subroutine calls and returns in a single cycle. with internal loop counters and loop stacks, the ad73460 executes looped code with zero overhead; no explicit jump instructions are required to maintain loops. two data address generators (dags) provide addresses for simultaneous dual operand fetches (from data memory and program memory). each dag maintains and updates four address pointers. whenever the pointer is used to access data serial port sport 2 ref adc3 analog front end section adc1 adc2 adc4 adc5 adc6 external address bus serial ports sport 0 shifter mac alu arithmetic units memory programmable i/o and flags byte dma controller timer adsp-2100 base architecture power-down control program sequencer dag 2 data address generators program memory address data memory address program memory data data memory data dag 1 16k dm (optional 8k) 16k pm (optional 8k) external data bus full memory mode sport 1 ad73460 figure 10. functional block diagram
ad73460 C21C rev. 0 (indirect addressing), it is post-modified by the value of one of four possible modify registers. a length value may be associated with each pointer to implement automatic modulo addressing for circular buffers. efficient data transfer is achieved with the use of five internal buses: ? program memory address (pma) bus ? program memory data (pmd) bus ? data memory address (dma) bus ? data memory data (dmd) bus ? result (r) bus the two address buses (pma and dma) share a single external address bus, allowing memory to be expanded off-chip, and the two data buses (pmd and dmd) share a single external data bus. byte memory space and i/o memory space also share the external buses. program memory can store both instructions and data, permit- ting the ad73460 to fetch two operands in a single cycle, one from program memory and one from data memory. the ad73460 can fetch an operand from program memory and the next instruction in the same cycle. in lieu of the address and data bus for external memory connec- tion, the ad73460 may be configured for 16-bit internal dma port (idma port) connection to external systems. the idma port is made up of 16 data/address pins and five control pins. the idma port provides transparent, direct access to the dsps on-chip program and data ram. an interface to low-cost byte-wide memory is provided by the byte dma port (bdma port). the bdma port is bidirectional and can directly address up to four megabytes of external ram or rom for off-chip storage of program overlays or data tables. the byte memory and i/o memory space interface supports slow memories and i/o memory-mapped peripherals with program- mable wait state generation. external devices can gain control of external buses with bus request/grant signals (br, bgh, and bg). one execution mode (go mode) allows the ad73460 to continue running from on-chip memory. normal execution mode requires the processor to halt while buses are granted. the ad73460 can respond to eleven interrupts. there can be up to six external interrupts (one edge-sensitive, two level- sensi tive and three configurable) and seven internal interrupts generated by the timer, the serial ports (sports), the byte dma port and the power-down circuitry. there is also a master reset signal. the two serial ports provide a complete synchro- nous serial interface with optional companding in hardware and a wide variety of framed or frameless data transmit and receive modes of operation. each port can generate an internal programmable serial clock or accept an external serial clock. the ad73460 provides up to 13 general-purpose flag pins. the data input and output pins on sport1 can be alternatively configured as an input flag and an output flag. in addition, there are eight flags that are programmable as inputs or outputs and three flags that are always outputs. a programmable interval timer generates periodic interrupts. a 16-bit count register (tcount) is decremented every n pro- cessor cycle, where n is a scaling value stored in an 8-bit register (tscale). when the value of the count register reaches zero, an interrupt is generated and the count register is reloaded from a 16-bit period register (tperiod). serial ports the ad73460 incorporates two complete synchronous serial ports (sport0 and sport1) for serial communications and multiprocessor communication. here is a brief list of the capabilities of the ad73460 sports. for additional information on serial ports, refer to the adsp- 2100 family user s manual , third edition. ? sports are bidirectional and have a separate, double- buffered transmit and receive section. ? sports can use an external serial clock or generate their own serial clock internally. ? sports have independent framing for the receive and trans- mit sections. sections run in a frameless mode or with frame synchronization signals internally or externally generated. frame sync signals are active high or inverted, with either of two pulsewidths and timings. ? sports support serial data word lengths from 3 to 16 bits and provide optional a-law and -law companding according to ccitt recommendation g.711. ? sport receive and transmit sections can generate unique interrupts on completing a data word transfer. ? sports can receive and transmit an entire circular buffer of data with only one overhead cycle per data word. an inter- rupt is generated after a data buffer transfer. ? sport0 has a multichannel interface to selectively receive and transmit a 24- or 32-word, time-division multiplexed, serial bitstream. ? sport1 can be configured to have two external interrupts (irq0 and irq1) and the flag in and flag out signals. the internally generated serial clock may still be used in this configuration. dsp section pin descriptions the ad73460 is available in a 119-ball pbga package. in order to maintain maximum functionality and reduce package size and pin count, some serial port, programmable flag, interrupt, and external bus pins have dual, multiplexed functionality. the external bus pins are configured during reset only, while serial port pins are software configurable during program execu- tion. flag and interrupt functionality is retained concurrently on multiplexed pins. in cases where pin functionality is reconfigurable, the default state is shown in plain text; alternate functionality is shown in italics. see pin function descriptions. memory interface pins the ad73460 processor can be used in one of two modes, full memory mode, which allows bdma operation with full exter- nal overlay memory and i/o capability, or host mode, which allows idma operation with limited external addressing capa- bilities. the operating mode is determined by the state of the mode c pin during reset and cannot be changed while the processor is running. see tables for full memory mode pins and host mode pins for descriptions.
rev. 0 ad73460 C22C full memory mode pins (mode c = 0) pin # of input/ name(s) pins output function a13:0 14 o address output pins for program, data, byte and i/o spaces d23:0 24 i/o d ata i/o pins for program, data, byte and i/o spaces (8 msbs are also used as byte memory addresses) host mode pins (mode c = 1) pin # of input/ name(s) pins output function iad15:0 16 i/o idma port address/data bus a0 1 o address pin for external i/o, pro- gram, data or byte access d23:8 16 i/o data i/o pins for program, data byte and i/o spaces iwr 1 i idma write enable ird 1 i idma read enable ial 1 i idma address latch pin is 1 i idma select iack 1 o idma port acknowledge configur- able in m ode d; open source note in host mode, external peripheral addresses can be decoded using the a0, cms , pms , dms , and ioms signals terminating unused pin the following table shows the recommendations for terminating unused pins. pin terminations i/o hi-z * pin three- reset caused unused name state (z) state by configuration xtal i i float clkout o o float a13:1 or o (z) hi-z br , ebr float iad12:0 i/o (z) hi-z is float a0 o (z) hi-z br , ebr float d23:8 i/o (z) hi-z br , ebr float d7 or i/o (z) hi-z br , ebr float iwr i i high (inactive) d6 or i/o (z) hi-z br , ebr float ird ii br , ebr high (inactive) d5 or i/o (z) hi-z float ial i i low (inactive) d4 or i/o (z) hi-z br , ebr float is i i high (inactive) d3 or i/o (z) hi-z br , ebr float iack float d2:0 or i/o (z) hi-z br , ebr float iad15:13 i/o (z) hi-z is float pms o (z) o br , ebr float dms o (z) o br , ebr float bms o (z) o br , ebr float ioms o (z) o br , ebr float cms o (z) o br , ebr float rd o (z) o br , ebr float pin terminations (continued) i/o hi-z * pin three- reset caused unused name state (z) state by configuration wr o (z) o br , ebr float br i i high (inactive) bg o (z) o ee float bgh o o float irq2 / pf7 i/o (z) i input = high (inactive) or program as output, set to 1, let float irql1 / pf6 i/o (z) i input = high (inactive) or program as output, set to 1, let float irql0 / pf5 i/o (z) i input = high (inactive) or program as output, set to 1, let float irqe / pf4 i/o (z) i input = high (inactive) or program as output, set to 1, let float sclk0 i/o i input = high or low, output = float rfs0 i/o i high or low dr0 i i high or low tfs0 i/o o high or low dt0 o o float sclk1 i/o i input = high or low, output = float rfs1/ irq0 i/o i high or low dr1/ fl1 i i high or low tfs1/ irq1 i/o o high or low dt1/fo o o float ee i i ebr ii ebg oo ereset ii ems oo eint ii eclk i i elin i i elout o o notes * hi-z = high impedance. 1. if the clkout pin is not used, turn it off. 2. if the interrupt/programmable flag pins are not used, there are two options: option 1: when these pins are configured as inputs at reset and function as interrupts and input flag pins, pull the pins high (inactive). option 2: program the unused pins as outputs, set them to 1, and let them float. 3. all bidirectional pins have three-stated outputs. when the pins is configured as an output, the output is hi-z (high impedance) when inactive. 4. clkin, reset, and pf3:0 are not included in the table because these pins must be used.
ad73460 C23C rev. 0 interrupts the interrupt controller allows the processor to respond to the eleven possible interrupts and reset with minimum overhead. the ad73460 provides four dedicated external interrupt input pins, irq2 , irql0 , irql1 , and irqe . in addition, sport1 may be reconfigured for irq0 , irq1 , flag_in, and flag_out, for a total of six external interrupts. the ad73460 also supports internal interrupts from the timer, the byte dma port, the two serial ports, software and the power-down control circuit. the interrupt levels are internally prioritized and individually maskable (except power down and reset). the irq2 , irq0 , and irq1 input pins can be programmed to be either level- or edge-sensitive. irql0 and irql1 are level- sensitive and irqe is edge-sensitive. the priorities and vector addresses of all interrupts are shown in table xvii. table xvii. interrupt priority and interrupt vector addresses interrupt vector source of interrupt address (hex) reset (or power-up with pucr = 1) 0000 ( highest priority ) power-down (nonmaskable) 002c irq2 0004 irql1 0008 irql0 000c sport0 transmit 0010 sport0 receive 0014 irqe 0018 bdma interrupt 001c sport1 transmit or irq1 0020 sport1 receive or irq0 0024 timer 0028 ( lowest priority ) interrupt routines can either be nested with higher priority interrupts taking precedence or processed sequentially. inter- rupts can be masked or unmasked with the imask register. individual interrupt requests are logically anded with the bits in imask; the highest priority unmasked int errupt is then selected. the power-down interrupt is nonmaskable. the ad73460 masks all interrupts for one instruction cycle following the execution of an instruction that modifies the imask register. this does not affect serial port autobuffering or dma transfers. the interrupt control register, icntl, controls interrupt nest- ing and defines the irq0 , irq1 , and irq2 external interrupts to be either edge- or level-sensitive. the irqe pin is an external edge-sensitive interrupt and can be forced and cleared. the irql0 and irql1 pins are external level-sensitive interrupts. the ifc register is a write-only register used to force and clear interrupts. on-chip stacks preserve the processor status and are automatic ally maintained during interrupt handling. the stacks are twelve levels deep to allow interrupt, loop and subroutine nesting. the following instructions allow global enable or disable servicing of the interrupts (including power-down), regardless of the state of imask. disabling the interrupts does not affect serial port autobuffering or dma. ena ints; dis ints; when the processor is reset, interrupt servicing is enabled. low power operation the ad73460 has three low power modes that significantly reduce the power dissipation when the device operates under standby conditions. these modes are: ? power-down ? idle ? slow idle the clkout pin may also be disabled to reduce external power dissipation. power-down the ad73460 processor has a low power feature that lets the processor enter a very low power dormant state through hard- ware or software control. following is a brief list of power-down features. refer to the adsp-2100 family user s manual , third edition, system interface chapter, for detailed information about the power-d own feature. ? quick recovery from power-down. the processor begins executing instructions in as few as 400 clkin cycles. ? support for an externally generated ttl or cmos processor clock. the external clock can continue running during power- down without affecting the 400 clkin cycle recovery. ? support for crystal operation includes disabling the oscillator to save power (the processor automatically waits 4096 clkin cycles for the crystal oscillator to start and stabilize), and letting the oscillator run to allow 400 clkin cycle start up. ? power-down is initiated by either the power-down pin ( pwd ) or the software power-down force bit. interrupt support allows an unlimited number of instructions to be executed before optionally powering down. the power-down interrupt can also be used as a nonmaskable, edge-sensitive interrupt. ? context clear/save control allows the processor to continue where it left off or start with a clean context when leaving the power-down state. ? the reset pin can also be used to terminate power-down. ? power-down acknowledge pin indicates when the processor has entered power-down. idle when the ad73460 is in the idle mode, the processor waits indefinitely in a low power state until an interrupt occ urs. when an unmasked interrupt occurs, it is serviced; exe cution then con- tinues with the instruction following the idle instruction. in idle mode idma, bdma, and autobuffer cycle steals still occur. slow idle the idle instruction on the ad73460 slows the processor s internal clock signal, further reducing power consumption. the reduced clock frequency, a programmable fraction of the normal clock rate, is specified by a selectable divisor given in the idle instruction. the format of the instruction is idle (n); where n = 16, 32, 64, or 128. this instruction keeps the proces- sor fully functional, but operating at the slower clock rate. while it is in this state, the processor s other internal clock signals, such as sclk, clkout, and timer clock, are reduced by the same ratio. the default form of the instruction, when no clock divisor is given, is the standard idle instruction.
rev. 0 ad73460 C24C when the idle (n) instruction is used, it effectively slows down the processor s internal clock and thus its response time to incoming interrupts. the one-cycle response time of the stan- dard idle state is increased by n , the clock divisor. when an enabled interrupt is rec eived, the ad73460 will remain in the idle st ate for up to a maximum of n processor cycles ( n = 16, 32, 64, or 128) before resuming normal operation. when the idle (n) instruction is used in systems that have an externally generated serial clock (sclk), the serial clock rate may be faster than the processor s reduced internal clock rate. under these conditions, interrupts must not be generated at a rate faster than can be serviced, due to the additional time the processor takes to come out of the idle state (a maximum of n processor cycles). system interface figure 11 shows a typical basic system configuration with the ad73460, two serial devices, a byte-wide eprom, and optional external program and data overlay memories (mode selectable). programmable wait state generation allows the pro- cessor to easily connect to slow peripheral devices. the ad73460 also provides four external interrupts and two serial ports or six external interrupts and one serial port. host memory mode allows access to the full external data bus, but limits addressing to a single address bit (a0) additional system peripherals can be added in this mode through the use of external hardware to generate and latch address signals. clock signals the ad73460 can be clocked by either a crystal or a ttl- compatible clock signal. the clkin input cannot be halted, changed during operation, or operated below the specified frequency during normal operation. the only exception is while the processor is in the power- down state. for additional information, refer to chapter 9, adsp-2100 family user s manual, third edition , for detailed information on this power-down feature. if an external clock is used, it should be a ttl-compatible signal running at half the instruction rate. the signal is con- nected to the processor s clkin input. when an external clock is used, the xtal input must be left unconnected. the ad73460 uses an input clock with a frequency equal to half the instruction rate; a 26.00 mhz input clock yields a 19 ns processor cycle (which is equivalent to 52 mhz). normally, instructions are executed in a single processor cycle. all device timing is relative to the internal instruction clock rate, which is indicated by the clkout signal when enabled. because the ad73460 includes an on-chip oscillator circuit, an external crystal may be used. the crystal should be connected across the clkin and xtal pins, with two capacitors con nected as shown in figure 12. capacitor values are dependent on crystal type and should be specified by the crystal manufacturer. a parallel-resonant, fundamental frequency, microprocessor-grade crystal should be used. a clock output (clkout) signal is generated by the processor at the processor s cycle rate. this can be enabled and disabled by the clk0dis bit in the sport0 autobuffer control register. sclk1 rfs1 or irq0 tfs1 or irq1 dt1 or fo dr1 or fi sport1 sclk0 rfs0 tfs0 dt0 dr0 sport0 a0-a21 data cs byte memory i/o space (peripherals) cs data addr data addr 2048 locations overlay memory two 8k pm segments two 8k dm segments a 13 0 d 23 8 a 10 0 d 15 8 d 23 16 a 13 0 14 24 fl0 2 pf3 clkin xtal addr13 0 data23 0 bms ioms pms dms cms br bg bgh pwd pwdack ad73460 system interface or controller 16 1 16 fl0 2 pf3 clkin xtal a0 data23 8 bms ioms ad73460 irq2 /pf7 irqe /pf4 irql0 /pf5 irql1 /pf6 mode c/pf2 mode b/pf1 mode a/pf0 host memory mode irq2 /pf7 irqe /pf4 irql0 /pf5 irql1 /pf6 mode c/pf2 mode b/pf1 mode a/pf0 full memory mode wr rd wr rd 1/2x clock or crystal afe * section or serial device afe * section or serial device d 23 0 1/2x clock or crystal sclk1 rfs1 or irq0 tfs1 or irq1 dt1 or fo dr1 or fi sport1 sclk0 rfs0 tfs0 dt0 dr0 sport0 afe * section or serial device afe * section or serial device pms dms cms br bg bgh pwd pwdack idma port ird /d6 iwr /d7 is /d4 ial/d5 iack /d3 iad15 0 * afe section can be connected to either sport0 or sport1 figure 11. basic system configuration clkin xtal clkout figure 12. external crystal connections
ad73460 C25C rev. 0 reset the reset signal initiates a master reset of the ad73460. the reset signal must be asserted during the power-up sequence to assure proper initialization. reset during initial power-up must be held long enough to allow the internal clock to stabi- lize. if reset is activated any time after power-up, the clock continues to run and does not require stabilization time. the power-up sequence is defined as the total time required for the crystal oscillator circuit to stabilize after a valid v dd is applied to the processor, and for the internal phase-locked loop (pll) to lock onto the specific crystal frequency. a minimum of 2000 clkin cycles ensures that the pll has locked, but does not include the crystal oscillator start-up time. during this po wer-up sequence the reset signal should be held low. on any sub- sequent resets, the reset signal must meet the minimum pulsewidth specification, t rsp . the reset input contains some hysteresis; however, if an rc circuit is used to generate the reset signal, an external schmidt trigger is recommended. the master reset sets all internal stack pointers to the empty stack condition, masks all interrupts and clears the mstat register. when reset is released, if there is no pending bus re quest and the chip is configured for booting, the boot-loading sequence is performed. the first instruction is fetched from on-chip program memory location 0x0000 once boot loading completes. modes of operation table xviii summarizes the ad73460 memory modes. setting memory mode memory mode selection for the ad73460 is made during chip reset through the use of the mode c pin. this pin is multi- plexed with the dsp s pf2 pin, so care must be taken in how the mode selection is made. the two methods for selecting the value of mode c are active and passive. passive configuration involves the use a pull-up or pull-down resistor connected to the mode c pin. to minimize power con- sumption, or if the pf2 pin is to be used as an output in the dsp application, a weak pull-up or pull-down, on the order of 100 k ? , can be used. this value should be sufficient to pull the pin to the desired level and still allow the pin to operate as a pro- grammable flag output without undue strain on the processor s output driver. for minimum power consumption during power- down, reconfigure pf2 to be an input, as the pull-up or pull-down will hold the pin in a known state, and will not switch. active configuration invol ves the use of a three-statable external driver connected to the mode c pin. a driver s out- put enable should be connected to the dsp s reset signal such that it only drives the pf2 pin when reset is active (low). when reset is deasserted, the driver should three- state, thus allowing full use of the pf2 pin as either an input or output. to minimize power consumption during power-down, configure the programmable flag as an output when connected to a three-stated buffer. this ensures that the pin will be held at a constant level and not oscillate should the three-state driver s level hover around the logic switching point. memory architecture the ad73460 provides a variety of memory and peripheral interface options. the key functional groups are program memory, data memory, byte memory, and i/o. refer to the following figures and tables for pm and dm memory allocations in the ad73460. program memory program memory (full memory mode) is a 24-bit-wide space for storing both instruction opcodes and data. the ad73460-80 has 16k words of program memory ram on chip (the ad73460-40 has 8k words of program memory ram on chip), and the capability of accessing up to two 8k external memory overlay spaces using the external data bus . table xviii. modes of operation 1 mode c 2 mode b 3 mode a 4 booting method 0 0 0 bdma feature is used to load the first 32 program memory words from the byte memory space. program execution is held off until all 32 words have been loaded. chip is configured in full memory mode. 5 0 1 0 no automatic boot operations occur. program execution starts at external memory location 0. chip is configured in full memory mode. bdma can still be used, but the processor does not automatically use or wait for these operations. 1 0 0 bdma feature is used to load the first 32 program memory words from the byte memory space. program execution is held off until all 32 words have been loaded. chip is configured in host mode. (requires additional hardware.) 1 0 1 idma feature is used to load any internal memory as desired. program execution is held off until internal program memory location 0 is written to. chip is configured in host mode. 5 notes 1 all mode pins are recognized while reset is active (low). 2 when mode c = 0, full memory enabled. when mode c = 1, host memory mode enabled. 3 when mode b = 0, auto booting enabled. when mode b = 1, no auto booting. 4 when mode a = 0, bdma enabled. when mode a = 1, idma enabled. 5 considered as standard operating settings. using these configurations allows for easier design and better memory management.
rev. 0 ad73460 C26C program memory (host mode) allows access to all internal memory. external overlay access is limited by a single exter- nal address line (a0). external program execution is not available in host mode due to a rest ricted data bus that is only 16 bits wide. table xix. pmovlay bits pmovlay memory a13 a12:0 0 internal not applicable not applicable 1 external 0 13 lsbs of address overlay 1 between 0x2000 and 0x3fff 2 external 1 13 lsbs of address overlay 2 between 0x2000 and 0x3fff accessible when pmovlay = 2 0x2000 0x3fff 2 external memory accessible when pmovlay = 1 0x2000 0x3fff 2 always accessible at address 0x0000 0x1fff accessible when pmovlay = 0 3 pm (mode b = 0) internal memory 0x2000 0x3fff 8k internal pmovlay = 0 3 or 8k external pmovlay = 1 or 2 0x3fff 0x2000 0x1fff 8k internal 0x0000 program memory mode b = 0 address 8k internal pmovlay = 0 3 8k external program memory mode b = 1 address 0x3fff 0x2000 0x1fff 0x0000 accessible when pmovlay = 0 internal memory external memory 0x2000 0x3fff 0x0000 0x1fff 2 pm (mode b = 1) 1 reserved accessible when pmovlay = 0 3 reserved notes: 1 when mode b = 1, pmovlay must be set to 0 2 see table iii for pmovlay bits 3 not accessible on ad73422-40 figure 13. program memory map data memory data memory (full memory mode) is a 16-bit-wide space used for the storage of data variables and for memory-mapped control registers. the ad73460-80 has 16k words on data memory ram on chip (the ad73460-40 has 8k words on data memory ram on chip), consisting of 16,352 user-accessible locations in the case of the ad73460-80 (8,160 user-accessible locations in the case of the ad73460-40) and 32 memory- mapped registers. support also exists for up to two 8k external memory overlay spaces through the external data bus. all inter- nal accesses complete in one cycle. accesses to external memory are timed using the wait states specified by the dwait register. accessible when dmovlay = 2 accessible when dmovlay = 1 always accessible at address 0x2000 0x3fff accessible when dmovlay = 0 internal memory external memory 0x0000 0x1fff 0x0000 0x1fff 0x0000 0x1fff data memory 32 memory mapped registers 0x3fff 0x2000 0x1fff internal 8160 words 0x0000 data memory address 8k internal dmovlay = 0 or external 8k dmovlay = 1, 2 0x3fe0 0x3fdf figure 14. data memory map data memory (host mode) allows ac cess to all inte rnal memory. external overlay access is limited by a single external address line (a0). the dmovlay bits are defined in table xx. table xx. dmovlay bits dmovlay memory a13 a12:0 0 internal not applicable not applicable 1 external 0 13 lsbs of address overlay 1 between 0x2000 and 0x3fff 2 external 1 13 lsbs of address overlay 2 between 0x2000 and 0x3fff i/o space (full memory mode) the ad73460 supports an additional external memory space called i/o space. this space is designed to support simple con- nections to peripherals (such as data converters and external registers) or to bus interface asic data registers. i/o space supports 2048 locations of 16-bit wide data. the lower eleven bits of the external address bus are used; the upper three bits are undefined. two instructions were added to the core adsp-2100 family instruction set to read from and write to i/o memory space. the i/o space also has four dedicated 3-bit wait state registers, iowait0-3, that specify up to seven wait states to be automatically generated for each of four regions. the wait states act on address ranges as shown in table xxi. table xxi. wait states address range wait state register 0x000 C 0x1ff iowait0 0x200 C 0x3ff iowait1 0x400 C 0x5ff iowait2 0x600 C 0x7ff iowait3 composite memory select ( cms ) the ad73460 has a programmable memory select signal that is useful for generating memory select signals for memories mapped to more than one space. the cms signal is generated to have the same timing as each of the individual memory select signals ( pms , dms , bms , ioms ) but can combine their functionality. each bit in the cmssel register, when set, causes the cms signal to be asserted when the selected memory select is asserted. for example, to use a 32k word memory to act as both program and data memory, set the pms and dms bits in the cmssel register and use the cms pin to drive the chip select of the memory; use either dms or pms as the additional address bit.
ad73460 C27C rev. 0 the cms pin functions like the other memory select signals, with the same timing and bus request logic. a 1 in the enable bit causes the assertion of the cms signal at the same time as the selected memory select signal. all enable bits default to 1 at reset, except the bms bit. boot memory select ( bms ) disable the ad73460 also lets you boot the processor from one exter- nal memory space while using a different external memory space for bdma transfers during normal operation. you can use the cms to select the first external memory space for bdma trans- fers and bms to select the second external memory space for booting. the bms signal can be disabled by setting bit 3 of the system control register to 1. the system control register is illustrated in figure 15. system control register pwait program memory wait states 0000010000000111 1514131211109876543210 dm (0x3fff) bms enable 0 = enabled 1 = disabled sport0 enable 1 = enabled 0 = disabled sport1 enable 1 = enabled 0 = disabled sport1 configure 1 = serial port 0 = fi, fo, irq0, irq1, sclk figure 15. system control register byte memory the byte memory space is a bidirectional, 8-bit-wide, external memory space used to store programs and data. byte memory is accessed using the bdma feature. the bdma control regis- ter is shown in figure 16. the byte memory space consists of 256 pages, each of which is 16k 8. the byte memory space on the ad73460 supports read and write operations as well as four different data formats. the byte memory uses data bits 15:8 for data. the byte memory uses data bits 23:16 and address bits 13:0 to create a 22-bit address. this allows up to a 4 meg 8 (32-megabit) rom or ram to be used without glue logic. all byte memory accesses are timed by the bmwait register. byte memory dma (bdma, full memory mode) the byte memory dma controller allows loading and storing of program instructions and data using the byte memory space. the bdma circuit is able to access the byte memory space while the processor is operating normally, and steals only one dsp cycle per 8-, 16-, or 24-bit word transferred. bdma control bmpage btype bcr 0 = run during bdma 1 = halt during bdma 0000000000001000 1514131211109876543210 dm (0x3fe3) bdir 0 = load from bm 1 = store to bm figure 16. bdma control register the bdma circuit supports four different data formats that are selected by the btype register field. the appropriate number of 8-bit accesses are done from the byte memory space to build the word size selected. table xxii shows the data formats sup- ported by the bdma circuit. table xxii. data formats internal btype memory space word size alignment 00 program memory 24 full word 01 data memory 16 full word 10 data memory 8 msbs 11 data memory 8 lsbs unused bits in the 8-bit data memory formats are filled with 0s. the biad register field is used to specify the starting address for the on-chip memory involved with the transfer. the 14-bit bead register specifies the starting address for the external byte memory space. the 8-bit bmpage register specifies the start- ing page for the external byte memory space. the bdir register field selects the direction of the transfer. finally the 14-bit bwcount register specifies the number of dsp words to transfer and initiates the bdma circuit transfers. bdma accesses can cross page boundaries during sequential addressing. a bdma interrupt is generated on the completion of the number of transfers specified by the bwcount register. the bwcount register is updated after each transfer so it can be used to check the status of the transfers. when it reaches zero, the transfers have finished and a bdma interrupt is gener- ated. the bmpage and bead registers must not be accessed by the dsp during bdma operations. the source or destination of a bdma transfer will always be on-chip program or data memory. when the bwcount register is written with a nonzero value, the bdma circuit starts executing byte memory accesses with wait states set by bmwait. these accesses continue until the count reaches zero. when enough accesses have occurred to create a destination word, it is transferred to or from on-chip memory. the transfer takes one dsp cycle. dsp accesses to external memory have priority over bdma byte memory accesses. the bdma context reset bit (bcr) controls whether or not the processor is held off while the bdma accesses are occur- ring. setting the bcr bit to 0 allows the processor to continue operations. setting the bcr bit to 1 causes the processor to stop execution while the bdma accesses are occurring, to clear the context of the processor and start execution at address 0 when the bdma accesses have completed. the bdma overlay bits specify the ovlay memory blocks to be accessed for internal memory. internal memory dma port (idma port; host memory mode) the idma port provides an efficient means of communication between a host system and the ad73460. the port is used to access the on-chip program memory and data memory of the dsp with only one dsp cycle per word overhead. the idma port cannot be used, however, to write to the dsp s memory- mapped control registers. a typical idma transfer process is described as follows: 1. host starts idma transfer. 2. host checks iack control line to see if the dsp is busy.
rev. 0 ad73460 C28C 3. host uses is and ial control lines to latch either the dma starting address (idmaa) or the pm/dm ovlay selection into the dsp s idma control registers. iad[15] must be set to 0. 4. host uses is and ird (or iwr ) to read (or write) dsp inter- nal memory (pm or dm). 5. host checks iack line to see if the dsp has completed the previous idma operation. 6. host ends idma transfer. the idma port has a 16-bit multiplexed address and data bus and supports 24-bit program memory. the idma port is completely asynchronous and can be written to while the ad73460 is operating at full speed. the dsp memory address is latched and then automatically incremented after each idma transaction. an external device can therefore access a block of sequentially addressed memory by specifying only the starting address of the block. this increases throughput as the address does not have to be sent for each memory access. idma port access occurs in two phases. the first is the idma address latch cycle. when the acknowledge is asserted, a 14-bit address and 1-bit destination type can be driven onto the bus by an external device. the address specifies an on-chip memory location; the destination type specifies whether it is a dm or pm access. the falling edge of the address latch signal latches this value into the idmaa register. once the address is stored, data can either be read from or written to the ad73460 s on-chip memory. asserting the select line ( is ) and the appropriate read or write line ( ird and iwr respectively) signals the ad73460 that a particular transaction is required. in either case, there is a one-processor-cycle delay for synchronization. the memory access consumes one addi- tional processor cycle. once an access has occurred, the latched address is automati- cally incremented and another access can occur. through the idmaa register, the dsp can also specify the starting address and data format for dma operation. asserting the idma port select ( is ) and address latch enable (ial) directs the ad73460 to write the address onto the iad0 C 14 bus into the idma control register. if iad[15] is set to 0, idma latches the address. the idmaa register, shown below, is memory mapped at address dm (0x3fe0). note that the latched address (idmaa) cannot be read back by the host. the idma ovlay register is memory mapped at address dm (0x3fe7). see figure 17 for more information on idma and dma memory maps. idma control (u = undefined at reset) dm(0x3fe0) idmaa address idmad destination memory type: 0 = pm 1 = dm uuuuuuuuuuuuuuu 1514131211109876543210 figure 17. idma control/ovlay registers bootstrap loading (booting) the ad73460 has two mechanisms to allow automatic loading of the internal program memory after reset. the method for booting after reset is controlled by the mode a, b and c con- figuration bits. when the mode pins specify bdma booting, the ad73460 initiates a bdma boot sequence when reset is released. the bdma interface is set up during reset to the following defaults when bdma booting is specified: the bdir, bmpage, biad, and bead registers are set to 0, the btype register is set to 0 to specify program memory 24-bit words, and the bwcount register is set to 32. this causes 32 words of on- chip program memory to be loaded from byte memory. these 32 words are used to set up the bdma to load in the remaining program code. the bcr bit is also set to 1, which causes pro- gram execution to be held off until all 32 words are loaded into on-chip program memory. execution then begins at address 0. the adsp-2100 family development software (revision 5.02 and later) fully supports the bdma booting feature and can generate byte memory space compatible boot code. the idle instruction can also be used to allow the processor to hold off execution while booting continues through the bdma interface. for bdma accesses while in host mode, the addresses to boot memory must be constructed externally to the ad73460. the only memory address bit provided by the processor is a0. idma port booting the ad73460 can also boot programs through its internal dma port. if mode c = 1, mode b = 0 and mode a = 1, the ad73460 boots from the idma port. idma feature can load as much on-chip memory as desired. program execution is held off until on-chip program memory location 0 is written to. bus request and bus grant (full memory mode) the ad73460 can relinquish control of the data and address buses to an external device. when the external device requires access to memory, it asserts the bus request (br) signal. if the ad73460 is not performing an external memory access, it responds to the active br input in the following processor cycle by: ? three-stating the data and address buses and the pms , dms , bms , cms , ioms , rd , wr output drivers, ? asserting the bus grant ( bg ) signal, and ? halting program execution. if go mode is enabled, the ad73460 will not halt program execution until it encounters an instruction that requires an external memory access. if the ad73460 is performing an external memory access when the external device asserts the br signal, it will not three-state the memory interfaces nor assert the bg signal until the proces- sor cycle after the access completes. the instruction does not need to be completed when the bus is granted. if a single instruction requires two external memory accesses, the bus will be granted between the two accesses. when the br signal is released, the processor releases the bg signal, reenables the output drivers and continues program execution from the point at which it stopped.
ad73460 C29C rev. 0 the bus request feature operates at all times, including when the processor is booting and when reset is active. the bgh pin is asserted when the ad73460 is ready to execute an instruction, but is stopped because the external bus is already granted to another device. the other device can release the bus by deasserting bus request. once the bus is released, the ad73460 deasserts bg and bgh and executes the external memory access. flag i/o pins the ad73460 has eight general-purpose programmable input/ output flag pins. they are controlled by two memory-mapped registers. the pftype register determines the direction, 1 = output and 0 = input. the pfdata register is used to read and write the values on the pins. data being read from a pin config- ured as an input is synchronized to the ad73460 s clock. bits that are programmed as outputs will read the value being output. the pf pins default to input during reset. in addition to the programmable flags, the ad73460 has five fixed-mode flags, flag_in, flag_out, fl0, fl1, and fl2. fl0 C fl2 are dedicated output flags. flag_in and flag_out are available as an alternate configuration of sport1. note: pins pf0, pf1, pf2, and pf3 are also used for device configuration during reset. instruction set description the ad73460 assembly language instruction set has an algebraic syntax that was designed for ease of coding and readability. the assembly language, which takes full advantage of the processor s unique architecture, offers the following benefits: ? the algebraic syntax eliminates the need to remember cryp- tic assembler mnemonics. for example, a typical arithmetic add instruction, such as ar = ax0 + ay0, resembles a simple equation. ? every instruction assembles into a single, 24-bit word that can execute in a single instruction cycle. ? the syntax is a superset adsp-2100 family assembly lan- guage and is completely source and object code compatible with other family members. programs may need to be relo- cated to utilize on-chip memory and conform to the ad73460 s interrupt vector and reset vector map. ? sixteen condition codes are available. for conditional jump, call, return, or arithmetic instructions, the condition can be checked and the operation executed in the same in struc- tion cycle. ? multifunction instructions allow parallel execution of an arithmetic instruction with up to two fetches or one write to processor memory space during a single instruction cycle. designing an ez-ice-compatible system the ad73460 has on-chip emulation support and an ice-port, a special set of pins that interface to the ez-ice. these features allow in-circuit emulation without replacing the target system processor by using only a 14-pin connection from the target system to the ez-ice. target systems must have a 14-pin con- nector to accept the ez-ice s in-circuit probe, a 14-pin plug. see the adsp-2100 family ez-tools data sheet for complete information on ice products. issuing the chip reset command during emulation causes the dsp to perform a full chip reset, including a reset of its memory mode. therefore, it is vital that the mode pins are set correctly prior to issuing a chip reset command from the emulator user interface. if you are using a passive method of maintaining mode information (as discussed in setting memory modes) then it does not matter that the mode information is latched by an emulator reset. however, if you are using the reset pin as a method of setting the value of the mode pins, then you have to take into consideration the effects of an emulator reset. one method of ensuring that the values located on the mode pins are those desired is to construct a circuit like the one shown in figure 18. this circuit forces the value located on the mode a pin to logic high; regardless if it latched via the reset or ereset pin. reset ereset ad73460 mode a /pfo programmable i/o figure 18. mode a pin/ez-ice circuit the ice-port interface consists of the following ad73460 pins: ebr ebg ereset ems eint eclk elin elout ee these ad73460 pins must be connected only to the ez-ice connector in the target system. these pins have no function except during emulation, and do not require pull-up or pull-down resistors. the traces for these signals between the a d73460 and the connector must be kept as short as possible, no longer than three inches. the following pins are also used by the ez-ice: br bg reset gnd the ez-ice uses the ee (emulator enable) signal to take control of the ad73460 in the target system. this causes the processor to use its ereset , ebr , and ebg pins instead of the reset , br , and bg pins. the bg output is thre e-stated. these signals do not need to be jumper-isolated in your system. the ez-ice connects to your target system via a ribbon cable and a 14-pin female plug. the ribbon cable is 10 inches in length with one end fixed to the ez-ice. the female plug is plugged onto the 14-pin connector (a pin strip header) on the target board. 1k
rev. 0 ad73460 C30C target board connector for ez-ice probe the ez-ice connector (a standard pin strip header) is shown in figure 19. you must add this connector to your target board design if you intend to use the ez-ice. be sure to allow enough room in your system to fit the ez-ice probe onto the 14-pin connector. 12 34 56 78 9 10 11 12 13 14 gnd key (no pin) reset br bg top view ebg ebr elout ee eint elin eclk ems ereset figure 19. target board connector for ez-ice the 14-pin, 2-row pin strip header is keyed at the pin 7 loca- tion you must remove pin 7 from the header. the pins must be 0.025 inch square and at least 0.20 inch in length. pin spac- ing should be 0.1 0.1 inches. the pin strip header must have at least 0.15-inch clearance on all sides to accept the ez-ice probe plug. pin strip headers are available from vendors such as 3m, mckenzie, and samtec. target memory interface for your target system to be compatible with the ez-ice emulator, it must comply with the memory interface guide- lines listed below. pm, dm, bm, iom, and cm design your program memory (pm), data memory (dm), byte memory (bm), i/o memory (iom), and composite memory (cm) external interfaces to comply with worst-case device timing requirements and switching characteristics as specified in the dsp s data sheet. the performance of the ez-ice may approach published worst-case specification for some memory access timing requirements and switching characteristics. note: if your target does not meet the worst-case chip specifica- tion for memory access parameters, you may not be able to emulate your circuitry at the desired clkin frequency. depending on the severity of the specification violation, you may have trouble manufacturing your system as dsp compo- nents statistically vary in switching characteristic and timing requirements within published limits. restriction: all memory strobe signals on the ad73460 ( rd , wr , pms , dms , bms , cms , and ioms ) used in your target system must have 10 k ? pull-up resistors connected when the ez-ice is being used. the pull-up resistors are necessary because there are no internal pull-ups to guarantee their state during prolonged three-state conditions resulting from typical ez-ice debugging sessions. these resistors may be removed at your option when the ez-ice is not being used. target system interface signals when the ez-ice board is installed, the performance on some system signals changes. design your system to be compatible with the following system interface signal changes introduced by the ez-ice board: ? ez-ice emulation introduces an 8 ns propagation delay between your target circuitry and the dsp on the reset signal. ? ez-ice emulation introduces an 8 ns propagation delay between your target circuitry and the dsp on the br signal. ? ez-ice emulation ignores reset and br when single- stepping. ? ez-ice emulation ignores reset and br when in emulator space (dsp halted). ? ez-ice emulation ignores the state of target br in certain modes. as a result, the target system may take control of the dsp s external memory bus only if bus grant ( bg ) is asserted by the ez-ice board s dsp. analog front end (afe) interfacing the afe section of the ad73460 features six input channels each with 16-bit linear resolution. connectivity to the afe section from the dsp is uncommitted thus allowing the user the flexibility of connecting in the mode or configuration of their choice. this section will detail several configurations with no extra afe channels configured and with an extra afe section configured (using an external ad73360 afe). dsp sport to afe interfacing the sclk, sdo, sdofs, sdi, and sdifs must be connected to the sclk, dr, rfs, dt, and tfs pins of the dsp respec- tively. the se pin may be controlled from a parallel output pin or flag pin such as fl0 C 2 or, where sport power-down is not required, it can be permanently strapped high using a suitable pull-up resistor. for consistent performance the se pin should be synchronized to the rising edge of the amclk using a cir- cuit similar to that of figure 23. the areset pin may be connected to the system hardware reset structure or it may also be controlled using a dedicated control line. in the event of tying it to the global system reset, it is necessary to operate the device in mixed mode, which allows a software reset, otherwise there is no convenient way of resetting the device. tfs dt sclk dr rfs dsp section afe section sdifs sdi sclk sdo sdofs fl0 fl1 areset se figure 20. dsp to ad73460 afe connection
ad73460 C31C rev. 0 cascade operation where it is required to configure an extra analog input channels to the e xisting six channels on the ad73460 it is possible to cascade six more channels (using external ad73360 afes) by using the scheme described in figure 22. it is necessary how- ever to ensure that the timing of the se and areset signals is synchronized at each device in the cascade. a simple d-type flip-flop is sufficient to synchronize each signal to the master clock amclk as shown in figure 21. 1/2 74hc74 clk dq dsp control to se amclk se signal synchronized to amclk 1/2 74hc74 clk dq dsp control to areset amclk areset signal synchronized to amclk figure 21. se and areset sync circuit for cascaded operation there may be some restrictions in cascade operation due to the number of devices configured in the cascade and the serial clock rate chosen. the formula below gives an indication of whether the combination of sample rate, and serial clock can be success- fully cascaded. this assumes a directly coupled frame sync arrangement as shown in figure 20 and does not take any interrupt latency into account. 16 11617 f device count sclk s ?+ [(( ) ) ] when using the indirectly coupled frame sync configuration in cascaded operation it is necessary to be aware of the restrictions in sending control word data to all devices in the cascade. the user should ensure that there is sufficient time for all the control words to be sent between reading the last adc sample and the start of the next sample period. connection of a cascade, as shown in figure 22, is no more complicated than connecting a single device. instead of connect- ing the sdo and sdofs to the dsp s rx port, these are now daisy-chained to the sdi and sdifs of the next device in the cascade. the sdo and sdofs of the final device in the cascade are connected to the dsp s rx port to complete the cascade. se and areset on all devices are fed from the signals that were synchronized with the amclk using the circuit of figure 21. the sclk from only one device need be connected to the dsp s sclk input(s) as both devices will be running at the same sclk frequency and phase. tfs dt dr rfs afe sdifs sdi sclk sdo sdofs sclk device 1 amclk se areset additional ad73360 afe 74hc74 q0 q1 d1 d0 fl0 fl1 dsp section clk sdifs sdi sclk sdo sdofs device 2 mclk se reset ad73460 figure 22. connection of an ad73360 cascaded to the ad73460 interfacing to the afe s analog inputs the ad73460 features six signal conditioning inpu ts. each signal conditioning block allows the ad73460 to be used with either a single-ended or differential signal. the applied signal can also be inverted internally by the ad73460 if required. the analog input signal to the ad73460 can be dc-coupled, pro- vided that the dc bias level of the input signal is the same as the internal reference level (refout). figure 23 shows the recom- mended differential input circuit for the ad73460. the circuit of figure 23 implements first-order low-pass filters with a 3 db point at 34 khz; these are the only filters that must be imple- mented external to the ad73460 to prevent aliasing of the sampled signal. since the adc uses a highly oversampled approach t hat transfers the bulk of the antialiasing filtering into the digital domain, the off-chip antialiasing filter need only be of a low order. it is recommended that for optimum performance the capacitors used for the antialiasing filter be of high quality dielectric (npo). vin to input bias circuitry vinpx vinnx refout refcap voltage reference 0.047 f 0.047 f 100 100 0.1 f figure 23. example circuit for differential input (dc coupling)
rev. 0 C32C c01040C1C10/01(0) printed in u.s.a. ad73460 figure 24 details the dc-coupled input circuits for single-ended operation respectively. vin vinpx vinnx refout refcap voltage reference 100 0.047 f 0.1 f figure 24. example circuit for single-ended input (dc coupling) digital interface as there are a number of variations of sample rate and clock speeds that can be used with the ad73460 in a particular appli- cation, it is important to select the best combination to achieve the desired performance. high-speed serial clocks will read the data from the ad73460 in a shorter time, giving more time for processing at the expense of injecting some digital noise into the circuit. digital noise can also be reduced by connecting resistors (typ <50 ? ) in series with the digital input and output lines. the noise can be minimized by good grounding and layout. typically the best performance is achieved by selecting the slowest sample rate and sclk frequency for the required appli- cation as this will produce the least amount of digital noise. outline dimensions dimensions shown in inches and (mm). 119-ball plastic ball grid array (pbga) (b-119) a b c d e f g h j k l m n p r t u 7 6 5 4 3 2 1 0.050 (1.27) bsc 0.800 (20.32) bsc 0.300 (7.62) bsc 0.050 (1.27) bsc 0.126 (3.19) ref 0.033 (0.84) ref bottom view a1 top view 0.866 (22.00) 0.858 (21.80) 0.559 (14.20) 0.543 (13.80) 0.089 (2.27) 0.073 (1.85) detail a seating plane 0.037 (0.95) 0.033 (0.85) 0.028 (0.70) 0.020 (0.50) detail a 0.035 (0.90) 0.024 (0.60) ball diameter 0.022 (0.56) ref

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