CN0540 IEPE Acquisition Board evaluation tips

Hi JustGreg2,

The FFT size is really going to be dependent on the sensor you are using, the vibrations you are trying to capture, sampling rate of the converter, and any digital filtering you are doing. The AD7768-1 can run up as high as 256ksps so Nyquist says you can get signals up to128kHz at its maximum throughput, but there is a 54kHz single pole RC filter on the CN0540.  I'd say play around a bit here and look to see if there are any examples with your use case.

There are several things you can control on the CN0540.  The DAC bias is something that you must control in the system, as this is going to set the full scale input range into the differential amp and ultimately into the AD7768-1, and this value is different for various sensors. 

There are a few nice to have controls in the software as well but these aren't required, ADC shutdown, protection switch indicators, current source enable/disable, amplifier power mode.

If you end up with the flow from raw ADC codes directly into your PC for processing, I'd highly recommend using the software ADI has created because this is based on Linux and might help streamline your development.  The only major difference is that the platform being used is an FPGA not an MCU but for sake of system testing it'll get you to that step much faster.  The other benefit here is that it might help you with your FFT question, since we have some examples of streaming raw data directly into MATLAB or Python

Here's a link if you'd like to check out more on how that is put together.

CN0540 and the CoraZ7-07s [Analog Devices Wiki] 

And a link to the MATLAB and Python guides

Streaming Data from the CN0549 into Python Tools [Analog Devices Wiki]

Streaming Data from the CN0549 into MATLAB [Analog Devices Wiki]