AD7634BSTZ datasheet(30/32 Pages) AD

30 / 32 page

AD7634

Data Sheet

Rev. B | Page 30 of 32

SCIN

SCCLK

WARP

START

TEN

123

BUSY

HW/SW = 0

INVSCLK = 0

CNVST

SCCS

t36

t35

t37

BIPOLAR

IMPULSE

OB/2C

MODE[1:0] = 3

BIPOLAR = 0 OR 1

TEN = 0 OR 1

IMPULSE = 0 OR 1

WARP = 0 OR 1

PD = 0

t33

t34

t31

Figure 47. Serial Configuration Port Timing

MICROPROCESSOR INTERFACING

The AD7634 is ideally suited for traditional dc measurement

applications supporting a microprocessor, and ac signal proc-

essing applications interfacing to a digital signal processor. The

AD7634 is designed to interface with a parallel 8-bit or 18-bit wide

interface, or with a general-purpose serial port or I/O ports on a

microcontroller. A variety of external buffers can be used with

the AD7634 to prevent digital noise from coupling into the ADC.

SPI Interface

The AD7634 is compatible with SPI and QSPI digital hosts

and DSPs, such as Blackfin® ADSP-BF53x and ADSP-218x/

ADSP-219x. Figure 48 shows an interface diagram between

the AD7634 and the SPI-equipped ADSP-219x. To accom-

modate the slower speed of the DSP, the AD7634 acts as a slave

device, and data must be read after conversion. This mode also

allows the daisy-chain feature. The convert command could be

initiated in response to an internal timer interrupt.

The reading process can be initiated in response to the end-of-

conversion signal (BUSY going low) using an interrupt line of

the DSP. The serial peripheral interface (SPI) on the ADSP-219x

is configured for master mode (MSTR) = 1, clock polarity bit

(CPOL) = 0, clock phase bit (CPHA) = 1, and SPI interrupt enable

(TIMOD) = 0 by writing to the SPI control register (SPICLTx).

It should be noted that to meet all timing requirements, the SPI

clock should be limited to 17 Mbps allowing it to read an ADC

result in less than 1.1 μs. When a higher sampling rate is desired,

use one of the parallel interface modes.

BUSY

SDOUT

SDCLK

CNVST

AD7634*

PFx

SPIxSEL (PFx)

MISOx

SCKx

PFx OR TFSx

ADSP-219x*

*ADDITIONAL PINS OMITTED FOR CLARITY.

DVDD

MODE[1:0]

EXT/INT

INVSCLK

Figure 48. Interfacing the AD7634 to SPI Interface

AD7634BSTZ Datasheet(PDF) 30 Page - Analog Devices

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