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Thread: Can't flash some new T3.2's

  1. #1
    Junior Member
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    Nov 2016
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    Can't flash some new T3.2's

    I recently shippped a sensor product of about 150 units based on Teensy 3.2. Of that batch, I was unable to flash or connect with four of the T3.2's. The Vin/USB trace has not been cut. I'm using TeensyDuino Teensy to flash a fixed .hex file while the T3.2 was loose and not mounted on the board. The only thing I had done was solder male headers, including the underside 2x7's prior to flashing (yes, lots of soldering).

    Anything I should try or check? Blink does not appear to be loaded or at least doesn't run when USB applied. Are these possibly defective?

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Nov 2012
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    From your question, it's not clear to me if you've managed to program your code onto these boards once (but not again), or if they're still in the original condition as shipped by PJRC.

    All Teensy boards ship with the LED blink program in flash. So if you simply apply power, and if the flash still has that original code, the orange LED should blink. No USB communication is needed for the LED blink, only power. So if the flash hasn't been altered and you get no blink, the power is really the only thing to check. Well, if you've also soldered, check if pin 13 (the LED) has solder bridged to anything else, or any damage to the LED or nearby 470 ohm resistor.

    If they flash was programmed, then the board's behavior of course depends on whatever code you loaded. That's not nearly so simple to troubleshoot as the case where the flash is known to still have the original LED blink.

  3. #3
    Junior Member
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    Nov 2016
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    Since we had put out 150 units and it was in a crunch mode, I went back to look at my build notes and I don't have the notes on whether the T3.2's were flashed and then didn't run or couldn't flash to start with. They were just set aside as exceptions and I'm only now getting around to figuring out what was wrong with them. I have limited time to work on it before I just throw these guys away and move on. So right now, all I have are four T3.2's that can't be flashed.

    I took a couple of photos, top and bottom, and looked very closely at them with a magnifying desk lamp and don't see any issues with solder joints.

    So even though it's $80 worth of boards, I don't have a ton of time to figure out what's happening with them. Any suggestion on anything I can probe or other op to resurrect them?

    Solder photos attached.
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