Digital Multimeter project.. help needed

Discussion in 'Homework Help' started by yuanshikai, Oct 20, 2011.

  1. yuanshikai

    Thread Starter Member

    Sep 17, 2011
    we were asked to build a digital multimeter.. so i decided to make it with a pic16f877a microcontroller.. i've written the code and tried to simulate.. somehow it just doesn't work the way i want it to.. please help..i've attached my schematic and c code..
  2. chrisw1990

    Active Member

    Oct 22, 2011
    what is your multimeter measuring?
    what current do those segment displays take? (can the pic source enough or do you need a buffer/driver? have you measured the voltage out of the pic to see if its driving the voltages, but the segments arent lighting?)
    Also, you have no LED resistors?
  3. Jon Wilder

    New Member

    Oct 25, 2011
    I second the absence of anode resistors. On that note, have you considered using a multiplexed 4 digit display? Would use up less I/O pins and it's simple to write the code to drive it using a timer interrupt.


    Mine shows it with a 4 digit common anode display. The logic in code would be reversed but you can also find a 4 digit common cathode display and use NPN transistors to ground instead.
  4. chrisw1990

    Active Member

    Oct 22, 2011
    good one on the multiplexing, means you can have more modes and fancy bits;) lets face it, thats all you buy a multimeter for isnt it?;)
    what are the actual measurements you intend to take with this?