Frying PORT.B1 and B2?


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  1. #1
    Join Date
    May 2006
    Location
    Del Rio, TX, USA
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    343

    Unhappy Frying PORT.B1 and B2?

    After a power "Blink", followed a couple seconds later by a power failure, it seems as if my 18F4620 PORT.B1 and B2 is fried.

    I had it in a LAB-X1, which was powered by a small "wall wart", which was pluged into a surge protector (same one my computer runs off). I have modified the LAB-X1 to accomadate jumpers to change around the configuration of the board to accomadate different chips/projects. At the time, I was running the 4 data lines for a VFD (operates like a std LCD) off of B0-B4.

    I have verified the all of the other hardware works by running a 16F877A and 18F4550 without any problems. I've also tried various other tasks with the bum 18F4620 (flashing LEDs, detecting button press) with no positive results. Beside those two lost pins, I seems to work OK (timers, I2C, USART).

    I guess I am in a mild state of disbelief. I had the impression these little things were fairly robust.
    Is there anything I can do in the future to better protect the PIC?

    Regards,
    Steve

  2. #2
    Join Date
    May 2004
    Location
    NW France
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    3,581

    Unhappy no miracle to wait for ....

    Hi, Steve

    Always use series resistors not to reach the maximum port allowable current ...

    Sorry, but I do not have better.

    Using Brown out detect ... may be (inputs as defaults ... but does not protect from surges from peripherals ...).

    Alain
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  3. #3
    Join Date
    Aug 2005
    Location
    Denver
    Posts
    25

    Default I wouldn't be too sure....

    I've even plugged a couple of them backwards. It seems to take a whole lot to fry one. The only way I can think of to really test your chip would be to put the identical program in an identical chip and see if it has the same results.

  4. #4
    Join Date
    May 2006
    Location
    Del Rio, TX, USA
    Posts
    343

    Default

    Quote Originally Posted by mugwamp
    ...put the identical program in an identical chip...
    Yea, I've got a replacement on the way. Should get it in a day or so. But I am almost certian it'a a goner, or at least those pins. I'll check for sure though. I may be able to use it in a future project that does not need all those pins.

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