teensy 3.1, windows 8, and "unknown USB Device (Device descriptor request failed)"

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visualSound

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teensy 3.1, windows 8, and "unknown USB Device (Device descriptor request failed)"

Hey everone, I've had my arduino ide setup and working for quite some time now doing things with teensy, and other arduino platforms.

Recently today i got the error: "unknown USB Device (Device descriptor request failed)"
Not sure what to make of it, and unable to program the teensy anymore (the instant I plugged it in, it would run just a fraction of a second of whatever code was already present, then freeze)

I'm running external power, and the usb pad has been cut on a couple of the teensys I'm experiencing this with.. (it's been working for a while just fine)
I managed to get connected with another computer, re upload the same code, then I moved back over to my laptop, and got connected again strangely(com ports recognized, no strange errors, etc).

Now the teensy will run it's code when I upload it, but as soon as I unplug power and reconnect it freezes at the start of the program again.
(i'm running led's, so i'm seeing the first few frames then a freeze.)

Any thoughts much appreciated! I'll report back with what i find on my own if I resolve this!
 
It also seems that the teensy loader pushes whatever last compiled and uploaded sketch was used anytime the reset button is hit on any teensy..

The reset button on any of the teensys causes the program to reset and hang when the usb is not plugged in.. did I perhaps do something to the bootloader?

This also happens with the default strandtest.
 
Last edited:
DemolishunWork:

Thanks for that clarification! makes sense, however I'm still not sure why the teensy's would start their program and then freeze instantly.. They hadn't done this earlier. Any thoughts along those lines?

Regards.
 
Colossal idiot move!

I forgot to incorporate a delay in the setup to give the teensy time to get load everything properly..
I think I read more about this on the forums somewhere once upon a time and forgot.

problem solved:
delay(500);

:)
 
When Serial is using USB, and the PC is windows, I and others find that often there's a delay before windows enables the virtual serial port via USB.
Some people do this:
Code:
  Serial.begin(baud);
  while (!Serial)
      ; // loop. But can get stuck depending on the host PC's events.
  Serial.println("In setup()");
others do this
Code:
  Serial.begin(baud);
  delay(1000); // hope it's long enough delay
  Serial.println("In setup()");
 
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