Question
I am using 7 x AD5232 in Daisy Chain mode. The timing is not in the correct
order. Are there any known problems in this configuration?
Answer
There are no known issues with the AD5232 in daisy chain mode. The SDO line and
SCLK lines are gated by the /CS line. Data is latched from the serial shift
register into the address decode logic on the rising edge of /CS. To daisy
chain multiple AD523X devices, simply connect SDO to SDI and run a common SCLK
and /CS to all devices. To program many AD5302s in a "daisy chain"
configuration, pull the /CS lines low on all chips. Send the data into the CLK
and SDI pins of the first AD523X in the chain. The data format should be data
for the last potentiometer in the chain sent first. Once data for all
converters in the chain is sent, a positive edge on /CS will load data into all
potentiometers simultaneously.
You must always write the same word length to the chain of devices. For example
when two AD5232s are daisy chained together, you must always write 32 bits, for
4 devices, you must write 64 bits. If you only want to update the contents of a
single device, simply write a NOP to the device locations you do not wish to
update.
Also ensure that the recommended 2k pull-up resistor is used on SDO.
The most likely cause of a failure is in the digital interface.