Datasheet

Read-Back Operation
DB23 DB0
=Don’tCare
DB23=MSB
DB0=LSB
MultipleReadings
CS
SCLK
SDI
CommandtoRead
RegisterA
CommandtoRead
RegisterB
DB23 DB0 DB23 DB0 DB23 DB0
CommandtoRead
RegisterC
NOPCommand
orWriteCommand
DB23 DB0
SDO
Undefined Datafrom
RegisterA
DB23 DB0 DB23 DB0 DB23 DB0
Datafrom
RegisterB
Datafrom
RegisterC
DB23 DB0
SingleReading
CS
SCLK
SDI
READCommandSpecifies
RegistertobeRead
DB23 DB0
DB23 DB0
SDO
Undefined
DB23 DB0
NOPCommand
orWriteCommand
Datafrom
SelectedRegister
DAC8734
SBAS465A – MAY 2009 – REVISED SEPTEMBER 2009 .................................................................................................................................................. www.ti.com
The READ command is used to start read-back operation. However, before read-back operation can be initiated,
the SDO pin must be enabled by clearing the DSDO bit in the Command Register (DSDO = '0'); this bit is cleared
by default. Read-back operation is then started by executing a READ command (R/ W bit = '1'; see Table 2 ). Bits
A3 to A0 in the READ command select the register to be read. The remaining data in the command are don ’ t
care bits. During the next SPI operation, the data that appear on the SDO output are from the previously
addressed register. For a read of a single register, a NOP command can be used to clock out the data from the
selected register on SDO. Multiple registers can be read if multiple READ commands are issued. The readback
diagram in Figure 43 shows the read-back sequence. The read-back data format is the same format as what was
used to write to the device.
Figure 43. Read-Back Operation
24 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
Product Folder Link(s): DAC8734