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Static Discharge and Reseting.... — Parallax Forums

Static Discharge and Reseting....

czm8czm8 Posts: 3
edited 2007-03-22 16:19 in BASIC Stamp
Hello,

I'm working on a project with the BS2 and I'm having a problem with it resetting if there is a static discharge anywhere within a about 10 feet of it. It is very dry here so it gets pretty staticy for for example if someone walks by and touches the screw on the light switch my stamp just resets.

I'm wondering if anyone had suggestions on how to shield it?

I've tried placing the whole circuit in a grounded metal box and that didn't help. I also tried isolating it from ground by running it off battery power and making sure nothing was touching any metal.

Cheers!

Comments

  • stamptrolstamptrol Posts: 1,731
    edited 2007-02-22 19:54
    The Stamp shouldn't be overly sensitive to static. Do you happen to be leaving the serial programming cable connected?

    Have you got anything connected to the RESET pin on the stamp?

    What is the stamp mounted in? Carrier board? Prototyping board? Home-grown board?

    Cheers,

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    Tom Sisk

    http://www.siskconsult.com
    ·
  • czm8czm8 Posts: 3
    edited 2007-02-22 23:20
    No programing cable connected and the reset pin is tied to +5V. For now the circuit is built on a prototyping board.
  • czm8czm8 Posts: 3
    edited 2007-03-21 21:40
    Anybody else have any suggestions?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-03-22 00:18
    It is possible that static is causing a reset...I would take precautions against that and see if the problem persists...Take care.

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    Chris Savage
    Parallax Tech Support
  • allanlane5allanlane5 Posts: 3,815
    edited 2007-03-22 13:16
    "touches the screw on the light switch" -- what light switch?

    Is there a light switch feeding an input to the BS2? And is there a current limiting resistor on that?

    Is there sufficient capacitance on the BS2? Are you using a BOE (which should have sufficient capacitance)?

    Any static charge represents a large voltage, but a small amount of current. If you give that current somewhere to go besides into an I/O port of the BS2, the BS2 shouldn't 'see' it.

    Oh, and you say "reset" is tied to +5 -- through what?· a 10 Kohm resistor?· a wire?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2007-03-22 16:19
    I hadn't noticed that the reset pin was tied HIGH. Not only is that not a good idea but it can cause problems programming the BASIC Stamp. You wouldn't be able to program at all if it was tied directly to Vdd.· The reset line is internally pulled HIGH through a 10K resistor.· Whatever you do to the reset line is unlikely to help from EMI/RFI problems anyway because the brownout detector is still going to cause·a reset during a brownout and EMI/RFI problems can have very strange effects.

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    Chris Savage
    Parallax Tech Support
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