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RM48L952: ADC2 Pin 7 is not consistent with ADC1

Jamie Wardlaw
Expert 1895 points
Part Number: RM48L952

I'm looking to do some cross compares on two ADC channels that are shared between ADC1 ADC2. I've selected Pin 7 and Pin 14 for the analogue signals I will do the cross compare on. The intent is to use this as a diagnostic on the ADC's as the values should be consistent when sampled close together.

On ADC1 I have 10 channels configured and FIFO is set to 10.

On ADC2 I only have 2 channels configured and the FIFO is set to 2.

All timings etc are set the same and I use Group 1 in each case with software triggered conversion. First I run conversion on ADC1, then I run conversion on ADC2. Conversions do not run at the same time.

I am finding that the Pin 7 channel is not being read the same on ADC1 and ADC2. It appears to be stuck close to '0' on ADC2. The other channel, pin 14, is tracking well on both ADC1 and ADC2. See screenshot below.

What can I do to investigate why one of the pins is not being read properly on ADC2?

Thanks

Jamie

  • 0
    TI__Guru**** 196506 points

    Hello Jamie,

    For pin 7 and pin 14, do you mean ADC channels? or device pin number?

    1. RM48 device has 2 package: 144 QFP, and 337 BGA.

    2. Pin 7 and pin 14 on QFP package are PLTP, and GIO

    3. ADC1 Channel 7 (pin 61) is not shared with ADC2

    4. ADC1 channel 14 (pin 82) is shared with ADC2

  • 0 in reply to QJ Wang
    Expert 1895 points
    QJ, thanks for pointing this out. I was clearly suffering from Brain fade!!! I had forgot to check the mapping on the channels to see if it was a 1 to 1 but see now that it clearly isn't. Appreciate the fast response.