Datasheet

Data Sheet AD5381
Rev. D | Page 31 of 40
MICROPROCESSOR INTERFACING
Parallel Interface
The AD5381 can be interfaced to a variety of 16-bit microcon-
trollers or DSP processors. Figure 35 shows the AD5381 family
interfaced to a generic 16-bit microcontroller/DSP processor.
The lower address lines from the processor are connected to A0
to A5 on the AD5381. The upper address lines are decoded to
provide a
CS
,
LDAC
signal for the AD5381. The fast interface
timing of the AD5381 allows direct interface to a wide variety
of microcontrollers and DSPs, as shown in
Figure 35.
AD5381 to MC68HC11
The serial peripheral interface (SPI) on the MC68HC11 is
configured for master mode (MSTR = 1), clock polarity bit
(CPOL) = 0, and the clock phase bit (CPHA) = 1. The SPI is
configured by writing to the SPI control register (SPCR)—see
the MC68HC11 user manual. SCK of the MC68HC11 drives the
SCLK of the AD5381, the MOSI output drives the serial data
line (D
IN
) of the AD5381, and the MISO input is driven from
D
OUT
. The SYNC signal is derived from a port line (PC7).
When data is being transmitted to the AD5381, the
SYNC
line
is taken low (PC7). Data appearing on the MOSI output is valid
on the falling edge of SCK. Serial data from the MC68HC11 is
transmitted in 8-bit bytes with only eight falling clock edges
occurring in the transmit cycle.
03731-034
MC68HC11
AD5381
MISO
MOSI
SCK
PC7
SDO
RESET
SER/PAR
DIN
SCLK
SYNC
SPI/I
2
C
DVDD
Figure 34. AD5381-to-MC68HC11 Interface
03732-035
µCONTROLLER/
DSP PROCESSOR
1
AD5381
ADDRESS
DECODE
UPPER BITS OF
ADDRESS BUS
DATA
BUS
A5
D15
D0
A4
A3
A2
A1
A0
R/W
A5
A4
A3
A2
A1
A0
WR
REG1
REG0
D11
D0
CS
LDAC
1
ADDITIONAL PINS OMITTED FOR CLARITY.
Figure 35. AD5381-to-Parallel Interface