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Need help from ELECTRONIC Engineers

  • 22-04-2010 7:20pm
    #1
    joeyjoe
    Closed Accounts Posts: 3 ✭


    Thesis help, no electronics experience.

    How do I identify the high pin on a microcontrollerwhen i switch the circuit on. I know which one is the ground, I am using a 4.8v Ni- MH battery.

    Cheers


Comments

  • #2
    Red Alert
    Hosted Moderators Posts: 7,486 ✭✭✭Red Alert


    Do you mean the positive supply pin? You'll probably have to consult the microcontroller's documentation, because the position of the pin is arbitrary.


  • #3
    joeyjoe
    Closed Accounts Posts: 3 ✭joeyjoe


    The circuit is from an existing product, I wish to identify which pin goes 'high' (thats the word my lecturer used) when I press the on switch. What I will be doing is taking a wire from the positive input and crossing it to the 'high' pin and creating my own circuit off that. Hopefully this makes sense :-/

    Thanks again


  • #4
    jelly&icecream
    Registered Users, Registered Users 2 Posts: 477 ✭✭jelly&icecream


    Is there anything written on the chip? If there's a model number you can google it and the documentation will probably be available online.


  • #5
    spideog7
    Registered Users, Registered Users 2 Posts: 1,230 ✭✭✭spideog7


    Failing that (if it's a made to order part) you could use an oscilliscope and just probe the pins until you find the right one. Be careful not to load the pin with your circuit, put a buffer in between.


  • #6
    joeyjoe
    Closed Accounts Posts: 3 ✭joeyjoe


    spideog7 wrote: »
    Failing that (if it's a made to order part) you could use an oscilliscope and just probe the pins until you find the right one. Be careful not to load the pin with your circuit, put a buffer in between.

    Hey spideog,

    I have a voltmeter and have been using that, many of the pins are fluctuating -2v to 2v the high pin should read the same as the input voltage (4.8v right?


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  • #7
    DublinDilbert
    Registered Users, Registered Users 2 Posts: 5,401 ✭✭✭DublinDilbert


    Do you know what sort of IC you are looking at? What is it?

    What setting are you using the multimeter on?

    Can you measure the battery with your multimeter?

    Can you post a Picture of the circuit you are trying to measure?


  • #8
    gotBass
    Registered Users, Registered Users 2 Posts: 108 ✭✭gotBass


    Firstly are we talking a bout a pin that stay's hi or goes toggles hi-lo when the micro is powered?

    If it stays hi then a multimeter set to DC measurement should be ok.
    If unsure , get access to an oscilloscope as the old saying goes a picture paints a thousands words. With the oscilloscope you can see what happens to each pin over time, if it goes up and down you'll see it as along as the channel on the scope is set for DC.
    With most modern scopes you can take a screen capture of what the scope sees,and save to a USB key, it might be handy for your notes.

    For all measurement please be careful not to put the probe between 2 adjacent pins, as you run the risk of causing damage, to the micro.
    best of luck


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