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Thread: Teensy 4.0 seen as SE BLANK RT Family

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  1. #1
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    Teensy 4.0 seen as SE BLANK RT Family

    I have a teensy 4.0 that I started uploading example codes to. I was having issues receiving serial communication so I kept trying different example codes. Then I noticed that it did not show as a teensy device in windows device manager. Now I cannot enter manual program mode or see the teensy on Arduino IDE.

    I have tried a different computer that did not see teensy 4.0 at all.
    I have ~3.3V output from teensy
    I have 4.98V from power regulator to Vin
    I tried holding the reset button for 15 seconds but the Teensy only flashes red once
    Currently windows sees it as SE BLANK RT Family

  2. #2
    Senior Member+ defragster's Avatar
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    For the 15 sec Restore the Red Flash is when the Button should be released to complete the restore. Did that happen then followed by about a minute of Red LED on? If held seconds too long after the flash the Restore is aborted.

    That "SE BLANK RT Family" appears when the Teensy doesn't start with good USB.

    Perhaps unplug the T_4.0 and then hold the Button during plugging it in, and a half second after, before releasing.

    If that doesn't work then try the 15 sec Restore again with Button release when the RED LED flashes.

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    To clarify, plugging in the teensy should be followed by powering on the teensy? I have a separate power supply so I want to make sure that i have your instructions correct.

    After I release the button for the 15 second reset, the LED flashes once and then the LED never turns back on.

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    Senior Member+ defragster's Avatar
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    Quote Originally Posted by xdog12 View Post
    To clarify, plugging in the teensy should be followed by powering on the teensy? I have a separate power supply so I want to make sure that i have your instructions correct.

    After I release the button for the 15 second reset, the LED flashes once and then the LED never turns back on.
    If externally powered - hold the button until just after the Teensy gets power to make sure any code on the Teensy does not run, but stays in bootloader.

    If the timing is right for the 15 sec Restore LED flash and Button release, it should then go full RED for the duration of the FLASH Formatting and device Restore and then return to 1 sec Blink with NO USB when 'Factory code' is Restored.
    > if that doesn't happen then something isn't working right.

    Is the VIN<>VUSB trace cut on this Teensy?

    If running under external power that is 'up to spec' then USB need not be plugged in for the Restore to work.

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    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by xdog12 View Post
    After I release the button for the 15 second reset, the LED flashes once and then the LED never turns back on.
    Just to confirm, when you see that brief flash on the red LED, you're supposed to release the button. If you do release within a few seconds of that brief red blink, the red LED is supposed to turn on bright for about 30 seconds. You're not seeing that? It's just remaining off?

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    I have just tried your suggestions and the teensy will only flash red once. I can not get it to boot into blink. When I plugged the USB I cannot enter programming mode.

    I checked that the trace is cut and has no connectivity.

    I still have 3.3v from the teensy

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    Senior Member+ defragster's Avatar
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    Can a clear pic of Top and Bottom be shown to show soldering and attachments made?

    Perhaps if VIN were Reconnected to VUSB and the external power were not applied it would show something different under just USB power?

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    Quote Originally Posted by defragster View Post
    Can a clear pic of Top and Bottom be shown to show soldering and attachments made?

    Perhaps if VIN were Reconnected to VUSB and the external power were not applied it would show something different under just USB power?

    I took pictures of the top and bottom of the circuit https://imgur.com/a/vePtQUx

    I disconnected everything but the I2C connections and I soldered VIN to VUSB. Still nothing but a single red blink.

    For reference here is me forgetting rule 1 and frying the first teensy 4 https://www.reddit.com/r/arduino/com...exposed_wires/

    So the circuit was working until I made that mistake. What should I do now? Should I just get another board?

    Thank you for your quick responses.

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    Yes, one red blink and then nothing. I will take pictures and desolder the 5V later today.

  10. #10
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by xdog12 View Post
    Yes, one red blink and then nothing.
    That's definitely damaged hardware!

    Look for any damage or stray solder in the area near pins 22 & 23. Especially check the tiny pins on the chip facing pin 23. Signals shorted together in that part of the board would be the most likely explanation for the problem you're seeing (red LED does quick blink, but flash wipe with red LED on 30 seconds doesn't happen).

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    Quote Originally Posted by PaulStoffregen View Post
    That's definitely damaged hardware!

    Look for any damage or stray solder in the area near pins 22 & 23. Especially check the tiny pins on the chip facing pin 23. Signals shorted together in that part of the board would be the most likely explanation for the problem you're seeing (red LED does quick blink, but flash wipe with red LED on 30 seconds doesn't happen).


    Thank you for all of the help, I realized what happened. I didn't think that the PWM input wire from my electronic speed controller would send 5 volts as it is PWM input. So pin 23 is fried and I have to invest in proper level shifting for PWM going to the teensy AND PWM leaving teensy.

    With that lesson learned, can you take a look at my schematic https://imgur.com/a/OPM3Yi6 and let me know if this level shifter will work? SN74LVC4245A. I have 5 of 6 channels from my receiver 5V and 3 PWM outputs for motors. So will this SN74LVC4245A level shifter work or should I pick a different level shifter.

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    I have nothing on pin 22 but a pwm out to headers for servo motor on pin 23. I checked the board and did not find any stray conductive materials.

    Are you saying that this board is probably dead? Should I bother with desoldering the 5V and pwm outputs. I already accidentally fried a board due to exposed wires. This was the backup board that I'm slowly adding the components to.

  13. #13
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by xdog12 View Post
    Are you saying that this board is probably dead?
    I'm saying it's definitely damaged.

    The word "dead" normally means so badly damaged that it shows no response, or responds in a way that suggests repair is impossible. That's not the case here.

    The good news is we do have signs of life from all the parts. The main processor seems to be working, since it's able to appear as NXP's USB ID. The bootloader appears to be running, since it does detect you're pressed the button and blink the red LED after 15 seconds. With those results, it's very likely all the power supply and clock stuff is good.

    Since we know both chips are still up and running, the most likely explanation is something went wrong with the signals which connect between the 2 chips. Admittedly this does involve some guesswork from only the words written on this forum thread, but I have a pretty strong hunch this Teensy 4.0 might be salvageable if you can find whatever caused the 2 still-working chips to stop communicating.

  14. #14
    Senior Member PaulStoffregen's Avatar
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    Maybe remove that yellow wire and look for any stray solder.

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    Quote Originally Posted by PaulStoffregen View Post
    Maybe remove that yellow wire and look for any stray solder.

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    Yes, I removed that wire and tried to reset the board. The only wire that I have connected still is the I2C connections (green and blue wire). I will desolder it from the board this weekend.

    Thank you

  16. #16
    Senior Member PaulStoffregen's Avatar
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    I believe SN74LVC4245A should work. But the connection in your schematic seems strange to me.

    Looks like it's meant to have Teensy drive the B inputs with 3.3V signals and the A side act as 5V outputs.

    On page 10, the datasheet says the DIR input needs to be low for the B to A direction, but on your schematic I see it's connected through a 10K resistor to 5V.

    The OE' pin also needs to be low, as high gives "isolation" according to page 10. I see a 10K resistor connected to 5V.


    I also see what looks like 2 DCDC switching power supply modules. You should really add capacitors at the input and output of both. That Traco part in particular caused a lot of problems years ago. The words on Adafruit's web page about a 10uF capacitor came from my suggestion, as the Traco datasheet gives very wrong advice. It absolutely does require a 10uF capacitor located close to its VIN+ & GND pins. Other people have been burned by that part. It works fine if you add the capacitor, and works fine if the power supply has a low impedance, but will give you nothing but grief if used without a capacitor when you have a battery which changes impedance as it discharges.

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    Thank you for the information, I decided not to use those chips and instead I used a MC14504B for 5v -> 3v and txs0104E for 3v->5v. However I have to figure out why most of the outputs of the MC14504B are not correct. (between 1000 and 2000 PWM signal). I used .1 uf capacitors on both power lines but I did not use any resistors. Let me know if you see any red flags on the level shifters that I decided to use, I also added the 10uf capacitor.

    My real question right now is when I try to run any I2C codes the teensy gives me this error. Board at usb:0/140000/0/9 is not available. I used the example code for Arduino_LSM6DSOX and I could not get serial from the teensy 4. I then used a simple blink example code with serial and slowly added I2C to that. And I once again got the same error and I have to manually press the button on the teensy to upload different code. What do you think is causing the teensy to behave badly once I call i2C.

  18. #18
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by xdog12 View Post
    I have to manually press the button on the teensy to upload different code.
    Install Teensyduino 1.54. You almost certainly have an older version...

    https://www.pjrc.com/teensy/td_download.html

    1.54 may not necessarily solve all your problems. But it does have a new CrashReport feature which might help. Detail on this article (scroll to the end)

    https://www.pjrc.com/teensyduino-1-54-released/

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    I updated the software and now the teensy is communicating via serial that it cannot find the i2c device. I replaced the broken teensy 4 (i2c worked) with the new teensy 4 and now i2c is not working. I verified the connections between the devices and I am slowly desoldering everything that is attached. I also tried adding a delay. What should I try next.

  20. #20
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by xdog12 View Post
    What should I try next.
    Might be a good to get all this stuff tested on a solderless breadboard first?

  21. #21
    Senior Member+ KurtE's Avatar
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    Maybe it would help to see new pictures of what is hooked up.

    From your first pictures, it also looked like maybe you you connected +5v to pin 2
    Click image for larger version. 

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    Click image for larger version. 

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    But I can not tell if that connection was cut or not?

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