T3.6 not programming, but working

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dauntless89

dauntless89

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Hello all, been lurking for a while. Sifting through this place has been very helpful, but I've reached an issue that searching could not resolve.

I've got a T3.6 installed in a breadboard and running on external power (12v to 5v buck converter, connected to Vin) with the vUSB trace cut. I uploaded to it maybe 30-35 times over 3 or 4 hours as I refined the code for my project. Uploading automatically was somewhat inconsistent. 5 or 8 times I had to do it manually, then the last time, I got no response from the program button. I thought I had fried the board as I was moving wires around quite a bit, but the T3.6 is still running my code. If I open the serial monitor, it's running normally and I have full control over the running program.

I've found posts about this issue, and while I haven't tried heating or cooling the board, none of the other "squint out of one eye while sticking your tongue out and channeling your chi to press the button just right" solutions have worked. No combination of twisting or flexing the board and mashing the button will get 'er going. Are there any other suggestions before I break out the heat gun?

Thanks.
 
Maybe remove that power supply and try using Teensy again from USB power?

Some of those buck converters can be quite problematic, especially if used without additional capacitors on both input and output.
 
No dice.

On USB power, same exact symptoms. I jumped the ground and program contacts as suggested elsewhere, no dice. The onboard program button is working (continuity between ground and program with it pressed). Do I have a compromised board?
 
The reset function works by shorting the reset pin to ground, but nothing from the program pin. I even tried connecting it to physically different ground pins, again no luck.

I did solder on the Vin pin and the ground pin closest to the program button, and at one point I did fumble a jumper wire and dropped 12v from a car battery into the same ground bus the Teensy was connected to. I don't remember whether or not the Teensy reset, but it did upload successfully at least once after that smoke show and is still functioning normally otherwise, so far as I can tell. I'm wondering if maybe the MKL02Z32VFG4 got damaged and not the K66.

Edit: Checked program pin voltage, only seeing .2v where there should be 3.3v. I am concluding that I damaged the MK chip and am abandoning this board.
 
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