Hello Guys,
Good day.
Our customer is trying to baseline the Modular EVM board connected to the ADSx98 FE Rev C against their design which is almost identical to the Dev kit with a few deviations.
At the moment they cannot establish SPI communications with the microcontroller on board. They have already followed the troubleshooting steps on the FAQ below. However, there was no data on MISO line. They also used the START pin to force comms on MISO line, but no data was seen.
They measure VCAP3 with respect to AVSS. Attached is a spreadsheet of measurements for your review.
ADC chip pin measurements.xlsx
Their results are:
1) On the development kit, we have 7.2V on VCAP3 with respect to AVSS; and
2) On our design/custom board, we have 4.4V with respect to AVSS
Therefore, there is a difference of 2.8V between the development kit design and our custom board. What are you expecting to see with such discrepancies? Would it result in the chip not responding?
As for RESV1, they currently have it floating. They know that datasheet has specified that it "must" be tied to logic low (DGND). What can we expect if it is floating? Again, would it result in the chip not responding?
Thanks and regards,
Art
