AnsweredAssumed Answered

AD7734 not behaving like datasheet

Question asked by Bareil on Mar 3, 2016
Latest reply on May 10, 2016 by Bareil

Hi All,


I played for 2 days with this part and I still cannot figure out how to make it work properly.


To make things simple.. I have only activated AN0, all other channels are deactivated. I have set the "Channel Conversion Time" to get a sample every 1ms.


I have tried the continous conversion mode WITH and WITHOUT the Continous read mode and there are problems with both configurations.


1) The spi communication of this part seems to be Mode 3 (clock idle is high, but still wait for rising edge to sample data)

2) My communication works because I can set it in single conversion mode, idle mode, continous conversion, etc.


Consinuous Conversion WITH Cont RD=1

Positive: The RDY line is high for 210us and then falls. I send 00h, 00h, 00h and I get my 16bits values then the RDY line goes back up!

Negative:  Sample values are junk. And "Channel Conversion Time" is completely ignored


Consinuous Conversion WITH Cont RD=0

Positive: The samples are valid. They are related to the input voltage

Negative:  Lets say