Are all i/o's on microcontroller are considered as digital I/O's including ATD pins?

Discussion in 'General Electronics Chat' started by Nitin Sasture, Mar 2, 2016.

  1. Nitin Sasture

    Thread Starter New Member

    Nov 4, 2014
    I do want to ask if all the pins on microcontroller are digital i/o's?
    Since in a spec of freesclae datasheet.
    It was mentioned that all digital i/o's are clamped to 5V internally.Does it mean analog pins also clamped to 5V?
  2. ISB123

    Well-Known Member

    May 21, 2014
    Analog pins have ADC so they can read voltages between 0-5.
  3. Papabravo


    Feb 24, 2006
    Modern processors can assign multiple functions to a single pin. They can even be a mix of inputs and outputs on the same pin. Usually pins default to some state at power up and you really need to know what that state is. Many development problems revolve around making the wrong assumptions about what state a pin is actually in.
  4. WBahn


    Mar 31, 2012
    You'd have to look at the spec sheet, possibly very carefully, to determine if the clamping applies to the analog pins -- but it almost certainly does since it is usually the pad that performs this function and since, regardless of whether it is digital or analog I/O, the goal is to protect the chip from voltage above (or below) particular limits.
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    I know Microchip has specific warnings about the pins having both analog and digital functions. Seems there is a additional internal structure (the details escape me) that leads to the advice to never use such a pin to catch an over voltage. While the device remains safe the over voltage will creap into all the other analog pins thus corrupting their readings while the over voltage exists.

    Do check your spec sheet carefully if you are using that diode in your app. If you are just concerned about ESD they don't worry so much.