16f677 adc Issue
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  1. #1
    Join Date
    Jun 2005
    Posts
    52

    Default 16f677 adc Issue

    I am moving from a 16F684 to a 16F677 for more I/O and having an issue with RA0. If RA0 pin is disconnected (floating} I measure 5.2V. My Vcc is 4.98V. If I ground RA0 with 10K I measure 0.19V. I swapped in a 16F1507 and that has no problem and works as expected. Unfortunately I need eeprom. I must be missing something in my i/o config. Any suggestions?

    WPUA = 0 '%00000000
    ANSEL = %00101101 '16F677 ANSEL
    ANSELH = %00001110 '16F677 ANSELH
    CM1CON0 = 0 ' Comparators OFF NO Comparators on PIC16F1507
    CM2CON0 = 0

    Thanks,
    Ed

  2. #2
    Join Date
    May 2013
    Location
    australia
    Posts
    1,603

    Default Re: 16f677 adc Issue

    I measure 5.2V. My Vcc is 4.98V
    then your math is incorrect , @vcc= 4.98v thats 4.86mV per count , max count is 1023 which = 4.975V


    I must be missing something in my i/o config. Any suggestions?
    The maximum recommended impedance for analog sources is 10 kΩ

    your conversion clock = ?
    your fosc = ?
    your aquisition time = ?
    This is more entertaining than Free to Air TV

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