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TM4C1233H6PM: ADC at PE3 is not sampling and just showing maximum reading.

Moiz Husnain
Prodigy 10 points
Part Number: TM4C1233H6PM

Hi everyone! I'm doing a project related to EMG waves accusation and control using analysis of EMG waves. ADC is one of the major part of this project. So to accomplish this i configured PE3 and it was working very fine till now. Now it's just showing maximum reading. Either the pin is damaged or it is something else? Please note that it was working before my last use.

  • 0
    Guru 117855 points

    Feel your pain. Had you the foresight to measure the external signal - being directed to "PE3" - prior to your issue? Such always helps as it provides a benchmark.

    When you measure (via separate, NON MCU means) the voltage applied (now) to PE3 - what reveals?

    As to cause - should PE3 have been damaged - might the signal being applied have persisted - even when power to your MCU was removed? Or - might the signal level have exceeded the maximum ratings of PE3? (data found far to the back of the MCU Manual - under specifications)

    You should be able to "force PE3 to ground" via a short jumper wire - applied to your board's header. What does the "read" of PE3 show then?

    Should your external input signal register as "ok" - cannot you re-introduce it to "some other" ADC pin - and then alter your software to this new circumstance?

  • 0 in reply to cb1_mobile
    Guru 27665 points

    cb1_mobile said:
    When you measure (via separate, NON MCU means) the voltage applied (now) to PE3 - what reveals?

    And if you measure with a DMM you should also measure with an oscilloscope. High frequencies and beyond the rail spikes can do strange things to A/Ds and if your front end amplifier has started injecting high frequency signals into the A/D you might have an issue from that.

    Robert

  • 0 in reply to Robert Adsett
    Guru 117855 points
    Right you are (again) friend Robert. We remain "untold" of the performance offered by "Analog Front End."

    I note the poster claims PE3's ADC as, "not sampling" - it would be interesting to learn (just how) that claim was made - and supported. (especially as the ADC channel reports (only) the full scale value - which is quite possible when that input is chronically over-driven! (And sampled!)