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Hi Eric,
Welcome to the E2E forum !!!
The VCAP3 pin (Pin #55) is the output voltage of the internal charge pump circuit. The voltage on this pin should be AVDD+1.9V (4.4V = 2.5V + 1.9V ). You will see a different voltage if there is no clock to the device as the internal charge pump requires a system clock for operation. Please verify that you are using either the internal clock oscillator (CLKSEL pin = Low) or provide the device with an external clock.
Yes, Pin 31 (RESV1) needs to be tie to logic low (DGND).
Thanks
-TC
Hi TC,
We are using the internal clock oscillator (CLKSEL pin = Low). What can we expect if the voltages are different? No communications on the MISO line at all?
As for the RESV1, we have it floating at the moment. Again, would this result in no data coming out of the MISO line.
We have followed all troubleshooting steps for SPI comms, including trying to force a reset pulse. We also attempted to use the START pin to force comms on the MISO line. Both steps made no difference, we are still NOT getting data on the MISO line.
What do you propose we do next?
Cheers,
ES
Hi Eric,
The CLKSEL pin needs to be set to HIGH if you are using the internal clock oscillator. Please see Table 11 of the datasheet for the device clock setting. If you do not see the correct voltages on Pin 55 (VCAP3), the device either malfunctions or does not have a clock signal.
You may see an issue with the SPI communication if the RESV1 pin is left floating. Please tie it to DGND and verify the functionality of the SPI communication.
Thanks
-TC