using common WPD for 2 pics ??? What happens


+ Reply to Thread
Results 1 to 5 of 5
  1. #1
    xnihilo's Avatar
    xnihilo Guest

    Smile using common WPD for 2 pics ??? What happens

    Hello,

    In my deseign, I've connected two PIC16F690:
    RC0 is set as output, default low, with 100K WPD (because I need to set it as input low sometimes).
    On the second pic, RA5 is set as input, default low, with 100K WPD (because I need it to react to a positive pulse).
    RC0 from first pic is connected to RA0 of the second pic while both these pins are tied to GND with their respective WPD.
    Is it allright or should I use only one 100K WPD connected to the link between these two pins?

    I don't know if my topic is clear enough to understand???

  2. #2
    skimask's Avatar
    skimask Guest

    Default

    Put a 1k resistor inline with the wire. If one pin goes output high and the other pin goes output low and both chips are run from 5 volts, without the resistor, the PICs will try to pass XX amount of current, possibly damaging the pin drivers. With the inline 1K resistor, the max current that could pass between the 2 PICs on said line would be limited to around 5mA....well within the PICs limitations.

    Unless you have this line connected to the heating pad that is set up to burn somebody's skin...then you may want to run both PICs at 100VDC and let that unlimited thousand amps of current flow...

  3. #3
    xnihilo's Avatar
    xnihilo Guest

    Default

    Isn't there a limiter for the current a pic pin can sink (25 mA)???

    When you say "inline", you mean between the two pins, right? Sorry english is not the language I'm fluent with.

    Pics will grill if I use 100v and what is the "burn skin" stuff?

  4. #4
    skimask's Avatar
    skimask Guest

    Default

    Quote Originally Posted by xnihilo View Post
    Isn't there a limiter for the current a pic pin can sink (25 mA)???
    Yep, it's called 'smoke'. You try to pull much more than 25mA thru a pin on a PIC and you'll get smoke. That'll limit the current permanently...

    When you say "inline", you mean between the two pins, right? Sorry english is not the language I'm fluent with.
    Yes, inline, as in

    Pin -> Resistor -> Pin

  5. #5
    xnihilo's Avatar
    xnihilo Guest

    Default

    I got it. Thank you.

Similar Threads

  1. Communicating between two PICs over DC bus
    By elec_mech in forum mel PIC BASIC Pro
    Replies: 2
    Last Post: - 7th May 2009, 12:57
  2. Sharing Max232 with two pics?
    By zx81sp in forum Serial
    Replies: 10
    Last Post: - 28th April 2009, 22:22
  3. Multiple Pics accessing single EEPROM
    By Atom058 in forum mel PIC BASIC Pro
    Replies: 3
    Last Post: - 3rd February 2008, 17:22
  4. Retrieving infos from multiple PICs on a bus/chain
    By flotulopex in forum mel PIC BASIC Pro
    Replies: 7
    Last Post: - 15th October 2007, 04:42
  5. USB Pics, ICD2, pic basic pro
    By vacpress in forum USB
    Replies: 34
    Last Post: - 20th January 2007, 20:50

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts