AD5232: Daisy chain

Document created by analog-archivist Employee on Feb 23, 2016
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We're designing a audio interface and there raised a question about the daisy
chain configuration. In the datasheet is written that the SPI controller has to
send a data package containing two 16bit data fields. Thats understandable, but
what if we try to read from the an5232? Can we expect a 32bit package from the
an5232? And will this package leave the last chip in the daisy chain trhough
it's SDO?

 

To daisy chain multiple AD523X devices, simply connect SDO to SDI and run a
common SCLK and /CS to all devices.
To program many AD5235s 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 AD5235s 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 pullup resistor is used on SDO  !

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