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Reset pin of PIC

Discussion in 'Microcontrollers, Programming and IoT' started by Rajinder, Mar 18, 2019.

  1. Rajinder

    Rajinder

    348
    6
    Jan 30, 2016
    Hi,
    I have a reset pin of a PIC micro connected to 5V via a 10K pull up resistor.
    If i connect a I/O line of a second PIC to the reset of the first PIC. Can i reset the PIC by outputting a zero? Or should it be a logic 1?
    Thanks
     
  2. hexreader

    hexreader

    100
    16
    Apr 21, 2011
    Zero to reset, 1 to run.
     
  3. Rajinder

    Rajinder

    348
    6
    Jan 30, 2016
    Thanks.
    I wanted to ask what actually happens internally to the MCLR line of the PIC i.e. in terms of the FET/transistors.
    Is there any good sources to explain this?
    Thanks in advance.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    8,931
    1,766
    Nov 17, 2011
    The rest pin can be considered as a standard input pin which is connected to the reset inputs of all internal logic functions of the mcu.
    You should be familiar with the operation of CMOS logic gates. If not, read e.g. here.
     
  5. Rajinder

    Rajinder

    348
    6
    Jan 30, 2016
    Hi
    So am i correct in saying that the pull up is tied to VDD via an PMOS FET internally? A logic 1 will keep the MCLR high. A logic 0 will turn on the PMOS FET and short drain to source to 0V.
    Is that correct?
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

    8,931
    1,766
    Nov 17, 2011
    No. How should the MOSFET do that when tied to Vcc, not GND?

    Read here.
     
  7. Rajinder

    Rajinder

    348
    6
    Jan 30, 2016
    Hi
    Thanks for this. So i would need a switch i.e..FET or similar to bring the MCLR to 0V?
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

    8,931
    1,766
    Nov 17, 2011
    Do you really have to ask this? Isn't it obvious?
     
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