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When P1 Loads but will not function: — Parallax Forums

When P1 Loads but will not function:

R BaggettR Baggett Posts: 175
in PASM/Spin (P1)

Hi, This is not a problem, but just info in case it happens to someone else.

I have had some of my boards using P1 subjected to highly destructive events and come through with P1 unscathed. It's a really tough chip and not usually the root of strange problems..

Unfortunately though, when building LOTS of one-off equipment a board can develop an interesting history, much of which is not generally good for electronics.

Somehow, we managed to damage 3 of 10 boards in an assembly in a REALLY weird way. I don't know just what happened to cause this, and zap the P1 but not the EEPROM or the plethora of 3V3 Op Amps...

Symptom:
* On loading the calibration firmware for the board (P1 program), the board loads correctly, but does not communicate back to the terminal (We use PST) for the procedure. Board previously checked out and calibrated using the same program.

  • The crystal is working correctly (5 MHZ), but nothing else is happening.
  • Resetting the board loads from the EEPROM. (I can see data and clock) Still no worky
  • Load PST demo. same result.
  • examine board for hours.. everything is OK
  • In desperation, we change out the virtually indestructible P1
  • Problem Solved!

Again, it is a credit to the P1 that we consider it virtually indestructible. (when not visibly deconstructed)

Comments

  • R BaggettR Baggett Posts: 175

    Update:

    The method for destroying a P1 so it will load but nothing else:

    Build 20 or so of your boards into a fixture, the fixture to be grounded via mains cord in the usual NEC approved way.
    Connect one of these boards for development and/or maintenance via a Prop Plug in the usual way. (I used a laptop, on it's power supply)
    Obtain a second-hand cubicle chair. Choose one that makes an effective Van de Graff generator when decoupled from your posterior. (A large one is recommended.. Posterior, Chair or both)
    Touch your fixture to discharge a healthy spark. Fail to notice that the connected Propeller resets... each time... until it has had enough...

  • VonSzarvasVonSzarvas Posts: 3,555

    :D:'(
    Now sure whether to laugh or cry!! - just glad you learned something useful and solved it all without zapping yourself !!

    Thanks for sharing the moment.

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