AD5382
2-Byte Mode
PARALLEL INTERFACE
Following initialization of 2-byte mode, the user can update
channels sequentially. The device address byte is only required
once and the pointer address pointer is configured for auto-
increment or burst mode.
The SER/
pin must be tied low to enable the parallel
PAR
interface and disable the serial interfaces. Figure 7 shows the
timing diagram for a parallel write. The parallel interface is
controlled by the following pins:
The user must begin with an address byte (R/ = 0), after
W
Pin
CS
Active Low Device Select Pin.
Pin
which the DAC will acknowledge that it is prepared to receive
data by pulling SDA low. The address byte is followed by a
specific pointer byte (0xFF) that initiates the burst mode of
operation. The address pointer initializes to channel zero, the
data following the pointer is loaded to Channel 0, and the
address pointer automatically increments to the next address.
WR
On the rising edge of
A4 to A0 are latched; data present on the data bus is loaded into
the selected input registers.
, with
low, the addresses on Pins
CS
WR
REG0, REG1 Pins
The REG0 and REG1 bits in the data byte determine which
register will be updated. In this mode, following the initializa-
tion, only the two data bytes are required to update a channel.
The channel address automatically increments from Address 0
to Channel 31 and then returns to the normal 3-byte mode of
operation. This mode allows transmission of data to all
channels in one block and reduces the software overhead in
configuring all channels. A STOP condition at any time exits
this mode. Toggle mode is not supported in 2-byte mode.
Figure 33 shows a typical configuration.
The REG0 and REG1 pins determine the destination register of
the data being written to the AD5382. See Table 11.
Pins A4 to A0
Each of the 40 DAC channels can be addressed individually.
Pins DB13 to DB0
The AD5382 accepts a straight 14-bit parallel word on DB13 to
DB0, where DB13 is the MSB and DB0 is the LSB.
SCL
SDA
1
0
1
0
1
AD1
AD0
R/W
A7 = 1 A6 = 1 A5 = 1 A4 = 1 A3 = 1 A2 = 1 A1 = 1 A0 = 1
START COND
BY MASTER
ACK BY
CONVERTER
MSB
ACK BY
CONVERTER
ADDRESS BYTE
POINTER BYTE
SCL
SDA
REG1 REG0 MSB
LSB
MSB
LSB
ACK BY
AD538x
ACK BY
AD538x
MOST SIGNIFICANT DATA BYTE
LEAST SIGNIFICANT DATA BYTE
CHANNEL 0 DATA
SCL
SDA
REG1 REG0 MSB
LSB
MSB
LSB
ACK BY
ACK BY
CONVERTER
CONVERTER
MOST SIGNIFICANT DATA BYTE
LEAST SIGNIFICANT DATA BYTE
CHANNEL 1 DATA
SCL
SDA
REG1 REG0 MSB
LSB
MSB
LSB
ACK BY
ACK BY
STOP
CONVERTER
CONVERTER COND
MOST SIGNIFICANT DATA BYTE
LEAST SIGNIFICANT DATA BYTE
BY
MASTER
CHANNEL N DATA FOLLOWED BY STOP
Figure 33. 2-Byte, I2C Write Operation
Rev. 0 | Page 30 of 40
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