Connect with us

Pull up resistors in PIC Microcontrollers

Discussion in 'Microcontrollers, Programming and IoT' started by electronicsLearner77, Jul 22, 2017.

Scroll to continue with content
  1. electronicsLearner77

    electronicsLearner77

    162
    1
    Jul 2, 2015
    This is a general question and in particular to pic, internal to micro controllers there are pull up, pull down, weak pull up, weak pull down registers for enabling and disabling. I never touch this registers in general. How important these registers. Can someone please explain in case if i enable weak pull up or pull down. What actually happens inside the controller?
     
  2. Minder

    Minder

    3,092
    661
    Apr 24, 2015
    I generally do not use them, they are not really physical resistors, but equal to around 10K/15K equivalent, from Mosfets that can be turned on and off.
    M.
     
  3. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    They are used to avoid the need for an external resistor. For example, switch inputs require a pullup or pulldown so the state of the input is defined when the switch is open.

    That said, I have just made a board using a weak pullup for a switch input, and I can trigger the switch by touching the contacts on the bottom of the board, so the pullup is really weak. In the next revision, I intend to use an external resistor.

    Bob
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-