Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 18 of 18

Thread: Teensy 4.1 not responding to pressing button for sketch upload

  1. #1
    Senior Member
    Join Date
    Jun 2017
    Posts
    140

    Teensy 4.1 not responding to pressing button for sketch upload

    I have a brand new Teensy 4.1 that worked fine for a couple of days.

    Now, when I try to upload a program to it, nothing happens. When I press the programming button, the LED stops flashing and the sketch is not uploaded. Also, the computer loses the connection to the com port.

    I tried restarting the computer but it did not help. I also tried with another Teensy 4.1 with the same computer and everything works normally with another board.

    When that problem board is powered, it runs the last sketch that was uploaded to it. I am using Arduino 1.8.9 with Teensyduino 1.53. Is the board bricked?

    Is this potentially a fake chip or are there other reasons?

    Thanks in advance for the community's help.

  2. #2
    Junior Member
    Join Date
    May 2021
    Posts
    9


    Try out the troubleshooting guide under the headline "Teensy Not Recognized by Teensy Loader". Maybe it helps

  3. #3
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    Thank you, I tried but it does not help.

    The first time I plug the board in, LED lights up and computer recognizes it. When a sketch tries to be uploaded, nothing happens. Pressing the programming button does not do anything.

    If I press the button and hold it pressed while plugging in the cable (as the article recommends), this causes the computer to beep but com port is not recognized and LED is off.

    What else should I try?

  4. #4
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Posts
    14,846
    Not clear what is going on there ...

    Assuming the cable used for the working T_4.1 is also used when plugging in the other one?

    Unplug all the Teensys.

    Have the IDE open with a simple BLINK or other sketch done with a VERIFY build

    With TeensyLoader Open go to Help and select Verbose - that will have any interaction with the T_4.1 shown in the verbose window.

    Using that good cable hold the program Button when plugging it in and wait a second before releasing - that should leave it in Bootloader ready to upload a simple BLINK sketch. And it should log in the Verbose window and then have TeensyLoader program it if in 'Auto' mode.

    Results?

    If that works and it is ready to upload another sketch - maybe the same blink with a faster or slower blink that is obvious.

    If not try the 15 sec Restore. Press the Button and watch for a RED LED flash about 15 seconds and release the button at that point and the RED LED should then go ON for the duration of the FLASH Erase and restoring of the Factory blink code, and the steps above should then work.

  5. #5
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    Thank you @defragster.

    I loaded and verified the Blink app. I have also uploaded the verbose logs. Tried all the above but nothing helped.

    When I unplug the cable then replug it, the board is recognized. Once I press the button, the com port is gone ....

    I am happy to try anything else.
    Attached Files Attached Files

  6. #6
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Posts
    14,846
    Good you uploaded the Verbose - Paul might scan it.

    If it won't program that is not right, but one the button is pressed it will never show a COM port - it goes into HID mode for bootloader.

    Any notes on the 15 Sec Restore? Did the RED LED Flash and then stay on when Button was released?

  7. #7
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    After spending 15 seconds nothing happens ,,,,

  8. #8
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    24,766
    Do you have a voltmeter? Probably time to check if the board has 5V power on VIN and 3V power at the 3.3V pin.

  9. #9
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    Thank you Paul.

    I measured 4.89 at VIN, and 3.28 on the 3.3V pin

  10. #10
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    24,766
    Well that's a good sign. The 3.3V power means powerup sequence reached at least step 6 (of 8), details here:

    https://www.pjrc.com/store/ic_mkl02_t4.html

    Can you measure the voltage on the Program pin? It should be 3.3V. And when you press the button, it should go to zero volts.

  11. #11
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    Thanks Paul.

    Which pin is the Program pin?

  12. #12
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    When first connecting the board to the PC, the com port is found and the LED lights up.

    At that point, I measured a voltage under the button (Program Pin?) of 2.0 V. When I pressed the button, the 2.0V remain. But in the latter case, the computer no longer sees the COM port and the LED is off.

  13. #13
    Senior Member PaulS's Avatar
    Join Date
    Apr 2015
    Location
    Netherlands
    Posts
    610
    Click image for larger version. 

Name:	T41.png 
Views:	16 
Size:	247.3 KB 
ID:	25045

    Paul

  14. #14
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    Thank you for the Program pin location.

  15. #15
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    When I touch the program button with a single Voltmeter tip, the PC beeps.

    The voltage between Program pin and Ground is 3.3. When I press the program button, it goes to zero.

  16. #16
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    24,766
    Quote Originally Posted by jimmie View Post
    When I touch the program button with a single Voltmeter tip, the PC beeps.
    Does the same PC beep happen when you press & release the pushbutton?

    Sure sounds like it's trying to work, but can't.

    All signs point to both the main IMXRT processor and the MKL02 bootloader both working, but unable to communicate with each other. Obviously the main chip is working because it's still running your previously programmed code (which is USB Serial, not USB RawHID as originally shipped from PJRC). The bootloader chip also seems to be alive, because it's turning on the CPU voltage (powerup sequence step 7), and it's giving 3.3V on the Program pin which comes from its internal pullup. That it's doing *something* when Program changes is also a good sign that chip is alive. At least the good news is all the chips seem to be operating, so there's a chance this board might work again if whatever has gone wrong with the connection between them gets fixed.

    Is there any sign of damage to the PCB in the area just below pins 23-17? If pins 22 & 23 were soldered and any stray solder got onto the tiny pins of the nearby bootloader chip, that sort of shorting signals together would explains the way this board is behaving.

  17. #17
    Senior Member
    Join Date
    Jun 2017
    Posts
    140
    Thanks Paul.

    I think I understand now what has caused the problem. I am using a custom board which also has the Ethernet connection. To use that board, I desoldered the 2-row 6-pin connector to place a different one that connects directly to the board with the built-in Ethernet. Most likely, it is damage to that area is what has caused the problem. I did check the area again and while I cannot see any damage, I must have damaged something. I wish an RJ45 came integrated with that board :-).

    Thanks again for your help. I will be more careful next time.

  18. #18
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    24,766
    Oh how I wish we could integrate a RJ45. It kinda doesn't really fit...

    If you can carefully desolder the part and get the location where something went wrong, there's a pretty good chance this board might be salvageable, since both the chips appear to be alive. Then again, that much work might not be worthwhile to save only 1 board.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •