Datasheet

AD7952 Data Sheet
Rev. A | Page 30 of 32
SCIN
S
CCL
K
WARPTEN
123 67
BUSY
HW/SW = 0
INVSCLK = 0
CNVST
SCCS
t
8
t
36
t
35
t
37
4
PD
5
BIPOLAR
IMPULSE
OB/2C
X
89
SER/PAR = 1
BIPOLAR = 0 OR 1
TEN = 0 OR 1
IMPULSE = 0 OR 1
WARP = 0 OR 1
PD = 0
t
33
t
34
t
31
X
t
31
START
06589-045
Figure 46. Serial Configuration Port Timing
MICROPROCESSOR INTERFACING
The AD7952 is ideally suited for traditional dc measurement
applications supporting a microprocessor and ac signal
processing applications interfacing to a digital signal processor.
The AD7952 is designed to interface with a parallel 8-bit or
14-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 AD7952 to prevent digital noise from coupling
into the ADC.
SPI Interface
The AD7952 is compatible with SPI and QSPI digital hosts and
DSPs, such as Blackfin® ADSP-BF53x and ADSP-218x/ADSP-219x.
Figure 47 shows an interface diagram between the AD7952 and
the SPI-equipped ADSP-219x. To accommodate the slower
speed of the DSP, the AD7952 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 µs. When a higher sampling rate is desired,
use one of the parallel interface modes.
BUSY
CS
SDOUT
SDCLK
CNVST
AD7952*
PFx
SPIxSEL (PFx)
MISOx
SCKx
PFx OR TFSx
ADSP-219x*
*ADDITIONAL PINS OMITTED FOR CLARITY.
D
V
DD
SER/PAR
EXT/INT
RD
INVSCLK
06589-046
Figure 47. Interfacing the AD7952 to SPI Interface