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ADC variable is always stored with values

Domenic Pang
Prodigy 140 points


Hi guys, 

My ADC variable is always stored with random values even when I am not sending any input through the port that I am using, PB5. 

I did not send any input at all, I just power on my board and i debugged it. The first '0' I've gotten was before I run the program... 

  • 0
    Guru 117855 points

    Those addresses are all w/in MCU's SRAM - unless your program - or the MCU's default behavior - "clears" that memory area - what you note is expected.

    If we assume that you've fed that MCU's ADC input w/the same signal - it's likely that your VDDA, VSSA and/or your external analog signal handling - are sub-optimal.   (the large variation (26 our of ~200) in your ADC variable so advises.)  

    There are many posts (here) detailing the "care/handling" of external analog signals prior to their "introduction" to the MCU's ADC.  (look especially for poster "Robert.")

  • 0
    TI__Guru**** 244440 points
    Hello Domenic,

    The same variable is showing 4 different values (the variable is at the same address). Are you not refreshing the value after the conversion?

    Regards
    Amit
  • 0
    Guru 27665 points

    Domenic Pang said:
    I did not send any input at all

    Does this mean the input pin is floating? IE not connected to anything.

    Robert