MCLR causing trouble . .


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  1. #1
    Join Date
    Jun 2006
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    Bangalore, India
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    Thanks for the info . . .
    I've now got 120 ohm resistors in series with the segment pins.
    The buttons are given to a 1K then to GND, internal pullup enebled.
    I'm using pref board. Checked for loose contacts. Did find one but that didn't solve the strange reset problem.
    The IC is resetting when i just make a light touch on the MCLR pin.
    The MCLR pin is given to Vcc through a 10k resistor.
    I've got another clock using the very same circuit and it doesn't reset that easy.
    Could this be due to ESD ? ? ?

    The clock also has a battery backup.
    <img src="http://www.delabs-circuits.com/png_circuits/embedded/battery-backup.png">
    Pin 3 is used to monitor the mains input. (it is given to the output from the 5v reg ,and not the output of battery backup ,through a voltage divider network).
    Could the battery backup be causing a problem ?
    Last edited by shahidali55; - 20th December 2007 at 14:16.

  2. #2
    Join Date
    Nov 2005
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    Bombay, India
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    Is your power supply based on a transformer or is it one of those low cost capacitive coupled power supplies? I am suspecting that it is the latter one. Then your talk of ESD makes sense. The best option for you to get any valid answer is to post your entire schematic including the power supply. Without that, all answers will be conjecture.

    JF

  3. #3
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    Jun 2006
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    I'm using a SMPS power supply. (from a PC).
    Connecting GND to the case of the XTAL solved my problem.
    I've never had such a problem before and have no idea why giving GND to case of XTAL solved it . . .
    Thank you everyone for helping me out . . .

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