AnsweredAssumed Answered

AD7766 Data Ready problem.

Question asked by sameer69 on Jul 15, 2013
Latest reply on Aug 12, 2013 by jcolao

Hi,

 

I am using AD7766 in one of project where we need precision data conversion. I am using PIC32 micro controller for ADC interface. I am polling the data ready signal and reading the ADC code, which then I dump to the DAC AD5791. Finally we need corner frequency selectable filters for DAC O/P. Here we have taken the advantage of ADC's built in FIR filter. We change the Master clock as per the corner frequency selected. This way we can get around 100 DB attenuation. The Master clock is generated by Micro controller using timer.

 

I am using only one ADC, so I have kept CS as low. During power on, I reset the ADC and wait for Data Ready to go low. I start the SCLK and read the data.  Then wait for Data ready to go high and again low. This I run in the loop. Similarly when user choose different corner frequency through the keyboard, I change the master clock accordingly, reset the ADC and repeat above procedure. My problem is,

 

1. My Data ready signal changes as per the selected Master clock but it seems it is not consistent. ( I tried to capture it on DSO and observed that pulses not getting captured properly.)  We observed that ADC output varies continuously.

 

2. Can we really use the ADC FIR as mentioned earlier ? 

 

Pl. guide me.

 

Thanks and regards,

Sameer

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