Teensy 4.0 will receive USB power but won't connect to a computer as a USB device

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bigtony

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When I plug my Teensy into my computer with a USB cable (I know its not the cable or USB port because my other Teensy works fine) it will receive power and it will power my LEDs (super basic code) but my computer will not recognize it as a USB device. Hoping there's a quick fix to this, not sure what other information to provide, this was the last thing I was able to reboot onto my Teensy before this issue started occuring:

Code:
#include <Audio.h>
#include <Wire.h>
#include <SD.h>
#include <SPI.h>
#include <SerialFlash.h>
#include <Bounce.h>

AudioSynthWaveform    waveform1;
AudioOutputI2S        i2s1;
AudioConnection       patchCord1(waveform1, 0, i2s1, 0);
AudioConnection       patchCord2(waveform1, 0, i2s1, 1);
AudioControlSGTL5000  sgtl5000_1;

Bounce button0 = Bounce(0, 15);
Bounce button1 = Bounce(1, 15);
Bounce button2 = Bounce(2, 15);

int count=1;
int a1history=0, a2history=0, a3history=0;

void setup() {
  AudioMemory(10);
  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  Serial.begin(115200);
  sgtl5000_1.enable();
  sgtl5000_1.volume(0.3);
  waveform1.begin(WAVEFORM_SINE);
  delay(1000);
  analogWrite(0,0);
  analogWrite(1,160);
  analogWrite(2,80);
  a1history = analogRead(A1);
  a2history = analogRead(A2);
  a3history = analogRead(A3);
}




void loop() {
  Serial.print("Beep #");
  Serial.println(count);
  count = count + 1;
  waveform1.frequency(440);
  waveform1.amplitude(0.9);
  wait(250);
  waveform1.amplitude(0);
  wait(1750);
}

void wait(unsigned int milliseconds)
{
  elapsedMillis msec=0;

  while (msec <= milliseconds) {
    int a1 = analogRead(A1);
    int a2 = analogRead(A2);
    int a3 = analogRead(A3);
    if (a1 > a1history + 50 || a1 < a1history - 50) {
      Serial.print("Knob (pin A1) = ");
      Serial.println(a1);
      a1history = a1;
    }
    if (a2 > a2history + 50 || a2 < a2history - 50) {
      Serial.print("Knob (pin A2) = ");
      Serial.println(a2);
      a2history = a2;
    }
    if (a3 > a3history + 50 || a3 < a3history - 50) {
      Serial.print("Knob (pin A3) = ");
      Serial.println(a3);
      a3history = a3;
    }
  }
}

Thanks
 
Is the small Teensy Loader window open. If so, turn off Auto mode.

Then press the button on your Teensy 4.0. What happens with the red LED on the Teensy 4.0 and with the Teensy Loader window on your PC?
 
Is the small Teensy Loader window open. If so, turn off Auto mode.

Then press the button on your Teensy 4.0. What happens with the red LED on the Teensy 4.0 and with the Teensy Loader window on your PC?

Thanks for the quick reply! Auto mode is off, and the Program/Reboot buttons are greyed out. Tools > Port in the Arduino editor is also greyed out and it is not a connected USB device. Pressing the button on my Teensy does nothing and the red light does not turn on
 
Is the small Teensy Loader window open. If so, turn off Auto mode.

Then press the button on your Teensy 4.0. What happens with the red LED on the Teensy 4.0 and with the Teensy Loader window on your PC?

On my teensy I had the following pin connections:

GND > breadboard ground
Vin > +5V pin on LED strip
Digital Pins 0,1,2 > R,G,B on LED strip

I just saw a notification about a power surge on my USB port, but after repairing them via a little pop-up notification they seem to all work, and I'm still able to receive power to my Teensy but not USB connection.
 
Yea did I do something wrong from my description above to suggest I fried it!!! Im worried hahaha

A couple of questions - are you powering the LED strip just using the power supplied from the USB? or did you apply 5v power to the 5v pin plus have the USB connected to PC. If you disconnect the LED strip from the Teensy does the PC still recognize the T4. Did you try the 15 sec restore (make sure the LED strip is not connector). Hold the pgm button down for 15sec and when you see the little red led blink need the USB connector release it. It should reset the T4 but it does take a while for reset to finish.
 
Agreed, the first troubleshooting step is to completely disconnect everything (except the USB cable) from your Teensy.

When Auto mode is turned off, or when Teensy Loader is not running at all on your PC, the red light on Teensy 4.0 should turn on when you press the pushbutton.

Even if Teensy Loader is running in Auto mode, you should still see the red light blink briefly. But if Teensy Loader quickly reprograms and reboots your Teensy (that's when Auto mode does), then the red light will only blink for a brief moment while the it's being reprogrammed.

If the hardware is still working, you should always get some sort of activity on the red LED after you press the pushbutton on Teensy 4.0.
 
A couple of questions - are you powering the LED strip just using the power supplied from the USB? or did you apply 5v power to the 5v pin plus have the USB connected to PC. If you disconnect the LED strip from the Teensy does the PC still recognize the T4. Did you try the 15 sec restore (make sure the LED strip is not connector). Hold the pgm button down for 15sec and when you see the little red led blink need the USB connector release it. It should reset the T4 but it does take a while for reset to finish.


1. LED strip is powered just using the USB power. The Teensy is plugged into USB, the Vin pin is connected to the +5V pin on the LED strip.

2. The Teensy isn't recognized as a USB device whether the LED strip is connected or not. It still draws power though for some reason.

3. Nothing happens when I hold the button down on the board even for longer than 15 seconds
 
Agreed, the first troubleshooting step is to completely disconnect everything (except the USB cable) from your Teensy.

When Auto mode is turned off, or when Teensy Loader is not running at all on your PC, the red light on Teensy 4.0 should turn on when you press the pushbutton.

Even if Teensy Loader is running in Auto mode, you should still see the red light blink briefly. But if Teensy Loader quickly reprograms and reboots your Teensy (that's when Auto mode does), then the red light will only blink for a brief moment while the it's being reprogrammed.

If the hardware is still working, you should always get some sort of activity on the red LED after you press the pushbutton on Teensy 4.0.

I'm not seeing any activity when clicking the pushbutton whether all my pins are connected/disconnected or whether or not the Teensy loader is in Auto mode or not. My computer is not recognizing a new USB device when I plug in or unplug the board across any of my USB ports (which work fine with my other Teensy or with any of my other currently connected USB devices).

I tried the 15 second button hold reboot (held for probably close to 20-25 seconds) and saw no change in the behaviour described above
 
Looks like your hardware is damaged.

If you only connected LED strips which had no other source of power, and if you didn't solder to the 3.3V power pin, odds are good the damage is probably errant solder. If you can get a magnifier and bright light, maybe visually inspecting the board can help you find where things went wrong. Maybe carefully removing the solder can fix it?

But 2 things that kill a Teensy are external power, especially higher voltages like 12V, and accidentally touching the 5V or more to the 3.3V power pin. If either of those things happened, your Teensy is probably dead beyond repair. :(
 
Looks like your hardware is damaged.

If you only connected LED strips which had no other source of power, and if you didn't solder to the 3.3V power pin, odds are good the damage is probably errant solder. If you can get a magnifier and bright light, maybe visually inspecting the board can help you find where things went wrong. Maybe carefully removing the solder can fix it?

But 2 things that kill a Teensy are external power, especially higher voltages like 12V, and accidentally touching the 5V or more to the 3.3V power pin. If either of those things happened, your Teensy is probably dead beyond repair. :(

The only thing soldered to my board is the Audio Adapter, but I had tested that to be working long before I had any of these issues arise. I haven't added any external power to my setup either.

I don't think I would've accidentally touched the running 5V to the 3V pin since my Teensy was secured in a breadboard and the only running power line was from the 5V to the breadboard line with the +5V pin for the LED strip... is there any way for me to troubleshoot this?

Thanks again for all the help
 
Do you have a voltmeter? You could try measuring the power at VIN to GND (before the voltage regulator), and also at 3.3V to GND (after the voltage regulator). That would at least confirm if your Teensy is getting good power.

You didn't mention connecting anything to VBAT or the On/Off pin (and we haven't seen any photos). But if you did use those, remove the coin cell battery. Teensy 4.0 can go into an "off" mode and stay in that mode if VBAT is maintained above 1V.
 
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