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AD7190 Communication Problem

Question asked by adambrar on Apr 5, 2016
Latest reply on Apr 5, 2016 by JellenieR

I have two AD7190 chips that I cannot communicate with. I write 40 1's by writing 5 0xff's to reset the chip. I'm expecting the MISO/DOUT channel to be toggled every 20ms after a reset as the chip is in continuous conversion mode by default and I'm monitoring the spi bus using a digital logic analyzer, but the MISO channel and pin 23 stay low the whole time. I've also tried reading from all of the registers and writing to the gpocon register and testing p2 and p3 output with DOUT staying low and p2 and p3 also staying low.. Also, the !SYNC pin is help high.


Is there any other way to test to see what's wrong with the chip? Or am I doing anything wrong in communicating with them?


Below is a capture of the spi bus from a reset command and then wait for the !RDY pin to toggle. The top image is zoomed in on one 0xff byte sent and the bottom is zoomed out to show all 5 0xff bytes sent.





Thanks for any help!



UPDATE: Both analog and digital power supplies need to be connected to get the spi bus working. Everything working as expected now.