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Thread: Teensy 3.2 killed by failed upload

  1. #1
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    Teensy 3.2 killed by failed upload

    I have a project that failed to properly upload my hex file, and now my Teensy 3.2 seems dead. No, it's not really dead, it is electrically functional, but Windows does not see it any longer. HalfKay does not appear to be running, and it does not show up in devices, and every Teensy loader I have fails to see it. I have followed the troubleshooting guidelines, holding the program button while connecting power/usb, rebooting computer, etc. Nothing seems to bring it back to life. The sketch is not running, cannot connect to it via serial port, and HID is not seeing it at all. It seems to be bricked, but I am hoping that is not the case. Any help would be appreciated.

  2. #2
    Senior Member+ defragster's Avatar
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    A bad cable would explain that - otherwise a simple blink sketch after Verify and then Plug in button held and released should trigger system to upload.

    What version of IDE and TeensyDuino? Paul posted in past few days another way to check feedback … Cant-get-Teensy-out-of-quot-unknown-usb-device-descriptor-failed-state-quot-Windows-10

  3. #3
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    The cable is good. I just plugged in another Teensy (an LC I had on hand), and Windows see's it fine. I upload the blink sketch to the LC, it's fine. Plug in the 3.2, recompile the sketch for it, upload fails. I am using the latest version of the Arduino IDE and Teensyduino, at least for this test. Is it possible to brick a Teensy by uploading a bad sketch? Or more specifically, a failed upload of a sketch.

  4. #4
    Senior Member PaulStoffregen's Avatar
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    Where did you buy this Teensy?

  5. #5
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    I'm not sure, I own a bunch. Either from you directly or Amazon.

  6. #6
    Senior Member PaulStoffregen's Avatar
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    There are some counterfeits on the market, mostly through Aliexpress. The counterfeits do become bricked if you upload certain types of programs. For example, if you set the CPU speed to 24 MHz and upload any program, it will immediately brick the counterfeit. Of course a genuine Teensy 3.2 will work and be able to upload again.

  7. #7
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    It's theoretically possible I had a fake, but I've only ever ordered from you and Amazon. This one is very dead. I ordered a replacement to finish my testing and it is working well. I did notice the color of the circuit board is a bit different in this one. It also came from Amazon.

  8. #8
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    Please disregard the following message. See reply below.

    I received my replacement and have a new issue. I2C is not working at all. Not just with my project, I can run either the basic scanner or advanced scanner and it shows nothing. loop() runs, but nothing is ever printed. I have tried with 2 different I2C devices, both of which I know work, but nothing. Is it possible to get a new Teensy 3.2 board with broken I2C? That would be a first, and have about 2 dozen of these devices.
    Last edited by toddosborne; 11-24-2019 at 08:43 AM.

  9. #9
    Senior Member+ MichaelMeissner's Avatar
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    If the scanner shows nothing and seems to hang, that is a sign you need pull-up resistors. Many I2C devices have pull-up resistors, as does the prop shield or audio shield. But not everything does, and you also might want to run the scanner without having any I2C devices attached.

    A 2.2k resistor is usually the right value for simple I2C buses with reasonably short wires. You would need one resistor between pin 18/A4/SDA and 3.3v (in parallel to the I2C connection) and another resistor between pin 19/A5/SCL and 3.3v.

  10. #10
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    Thanks, I just figured it out. This is why I should not work on electronics at 3 AM after working all day. One of my I2C devices is a BME280 atmospheric pressure sensor. Has 4 pins VIN, GND, SCL, SDA, in that order. I soldered it in backwards. Lucky I didn't kill my Teensy. All is good now.

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