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Zapped pin0? — Parallax Forums

Zapped pin0?

Ryan C. PayneRyan C. Payne Posts: 38
edited 2005-07-25 03:15 in General Discussion
Well, I think I gone and done it... I somehow must have had the LCD wired wrong and it appears the CPU.pin0 no longer works? Is there a way to test for sure that this pin is now indeed dead?

cry.gif·cry.gifcry.gif

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-07-24 23:34
    Hello,

    ·· One way to test a pin, although not completely thorough, is to tie an LED with a 470 ohm resistor·between the pin and ground.· Make the pin HIGH, see if the LED lights.· Also tie the LED and resistor to Vdd, make the pin LOW, see if the LED lights.· Next make an input switch and test the pin as an input.· Make sure you download the code to make the pin an input before you wire the switch.· The switch will tie between the pin and ground.· Also from the pin will be a 10K resistor to Vdd.· Then read the input and see if you get a 0 or LOW when the button is pushed, and 1 or HIGH when not pressed.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Ryan C. PayneRyan C. Payne Posts: 38
    edited 2005-07-25 00:35
    Chris,

    Here's the skinny.. When I put the led and 470 ohm resistor on the pin and set it high, the pin LED lights. When I tie the pin to Vdd and make the pin low, it does not light. When the pin is made in input it appears to work correctly. It shows high when not pressed and low when pressed?

    So what does all this mean? It can source current but can no longer sink it?

    Ryan
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-07-25 02:09
    Ryan,

    ·· Could you please verify you connections during the second test.· I ask because your wording was that you tied the pin to Vdd, not the LED/Resistor...

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Ryan C. PayneRyan C. Payne Posts: 38
    edited 2005-07-25 02:15
    Sorry. It's been a long day.. Yeah, Vdd to resistor, resistor to LED, LED to pin. I performed all three tests on pin0 and on pin7. All three tests worked on pin7·and only the two worked on pin0.

    Ryan
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-07-25 03:13
    Ryan,

    ·· Then yes, it sounds like you have damaged the low-side driver on your Module.· You may have to use that pin for an input only...

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Ryan C. PayneRyan C. Payne Posts: 38
    edited 2005-07-25 03:15
    Lovely! Thanks for your help!

    Ryan
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