Teensy 3.2 gets "stuck" and won't mount COM port

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dlchambers

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This happens to me once in a while.

Using Teensy 3.2 as Arduino (teensyduino) on Win10.
I'm running the USB as Serial.

As I'm developing my program and I have a bug, sometimes the Teensy gets hosed. The bug must be some very bad memory thing :)

99.9% of the time, I just recompile/reprogram all is well - the USBSerial dismounts, the Teensy programs, then the USBSerial remounts.

However, sometimes (like now), after it programs, the USBSerial doesn't remount.

After a bunch of thrashing around, and never quite being sure what I did, everything comes back, the USBSerial will remounts, and I'm good to go.

Any ideas why a Teensy can get into a state where USBSerial won't remount, even after reprogramming?

Thanks,
-Dave
 
Depending on how you hosed yourself... Example Hang in an ISR or some other equally bad things, I have had problems where it would not automatically reprogram... To fix, I typically just press the program button on the teensy to get it into the bootloader and then it should upload new program.

Other times if for example you dump tons of stuff to a comm port and it hangs, I have had to unplug the Teensy and replug it back in...

If I have done something bad hardware wise where the Teensy draws too much power, I have had my USB system turn off that hardware port... Usually fixed by unplugging and replugging, other times reboot... Luckily I have not done this in a long time
 
Can you reliably program a simple blink program with USB and have it work? Or is it only your project code?

An easy to do bad thing is over run an array or violate a pointers valid memory - that seems to quickly kill USB. I've seen it before and a post the other day over ran an array by four bytes and that took out USB iIIRC.
 
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