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AD5422 Read Register in Daisy-chain configuration

Question asked by Daniel_M on Oct 22, 2014
Latest reply on Oct 26, 2014 by msamera

He,

for a new design we want to use 8 AD5422 DACs in a daisy-chain configuration, as described on page 28 in the data sheet. I think I understood how to write registers to all devices in the chain: Just continue to clock out the 24 bit word for the next device, while the LATCH pin remains low, so in our case I clock out 8 x 24 = 192 Bits total. The first word clocked out is for the last device in the chain, right?

Now, only the SDO output of that last device is connected to our CPU, at its respective SPI-input.

Here our question:

How can I read the STATUS registers of all devices?

Do I have to clockout first the read STATUS register pattern for all devices (192 clocks, same 24 bits wide word repeated 8 times) and then 192 NOP clocks to read all devices?

 

This question is very important for us, because the decision for daisy-chaining (and for using AD5422) has to be done before the hardware will be designed, and we don't have much time.

Thanks in advance.

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