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Thread: did i just kill my teensy 4.0? will not turn on when supplied power.

  1. #1

    did i just kill my teensy 4.0? will not turn on when supplied power.

    i have been working on a drone and decided to move my breadboard circuit to a protoboard. so first i had the radio receiver, IMU sensor and drone's 5V battery connected. things worked perfectly. i was able to see the radio commands the teensy was picking up from the radio transmitter and sending those signals to the motor pins.

    SO THEN, i soldered the four motor wires to PWM pins on the teensy. again, i have tested this on the breadboard multiple times and it was fine. but after soldering these motor pins, i plugged my teensy into the socket, saw it turn on but then get stuck in the program. so i just reconnected it and then it DIDN'T turn on.

    it is sharing the same power supply as the IMU sensor, and the IMU is turning on as in its LED shines. so i don't now what suddenly happened to the teensy. i then plugged it to my computer via the USB cable, expecting that my drone power supply soldering was probably bad, but even the usb cable did not turn the teensy on!! the LED on the teensy remained off.

    the drone power supply is only 5V, and i even threw in a capacitor, so i have no idea what went wrong. only danger could have been apply a greater than 5V voltage onto a teensy pin but that would only break that particular GPIO pin.

    i also held the reset button on the teensy for 14 seconds since that is the factory reset i believe and still nothing. oh yea, the arduino IDE does not recognize the teensy plugged in through the USB and im certain nothing is wrong with the USB cable.

    any help is appreciated!

  2. #2
    Senior Member+ defragster's Avatar
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    Quick note: T_4.0 is only usable with 3.3V voltage levels - it is not 5V tolerant on any pin but VIN.

  3. #3
    yep, Vin or the 5V pin. that is what i used.

  4. #4
    Senior Member+ defragster's Avatar
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    Had to 'note' because this suggested 5V may have touched a GPIO pin which could be enough to end the Teensy:
    only danger could have been apply a greater than 5V voltage onto a teensy pin but that would only break that particular GPIO pin.

  5. #5
    oh so it wouldn't break that pin but the entire board? yikes. it is possible that i plugged in my motors in reversed order. so instead of (G,5V,Digital) where digital connects to a PWM pin on teensy, it could have been (Digital,5V,G) where ground of the 5V connected to a PWM pin. would this destroy the board though? would this render the teensy as unresponsive when supplied any power?

  6. #6
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    Quote Originally Posted by aotfanburneraccount View Post
    could have been apply a greater than 5V voltage onto a teensy pin but that would only break that particular GPIO pin.
    No, it destroys the whole chip.

    If it does not respond to the long (14 secs) reset, it looks not good.

  7. #7
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    That is my messy rough schematic if it helps decipher anything. it is possible pins got shorted while i soldered them but i did continuity checks and and i didn't hear a beep between PWM motor pins. im gonna go cry now

  8. #8
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    Just in case: “ SO THEN, i soldered the four motor wires to PWM pins on the teensy”

    Are these motors directly connected? The self-inductance of the coils might generate voltages well over 5V, unless you (or the manufacturer of the motors) provided some protection, e.g. diodes parallel, of course in the reverse direction, so they will not conduct when powered by the teensy.

  9. #9
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by aotfanburneraccount View Post
    did continuity checks and and i didn't hear a beep between PWM motor pins.
    Be careful with this. On many multimeters, beeper mode puts the meter into the lowest ohms range, where it feeds the highest test current through your circuitry. All multimeter ohms measurement involves injecting a test current and measuring the resulting voltage, but the highest ohms ranges use much lower / safer current.

  10. #10
    I haven't learned about inductance yet in my engineering courses but no. They are connected to individual PWM pins. Each motor has a digital pin that is connected to pins 6,7,8,9. I think I just accidentally connected the motor pin connector in reverse order so the ground pin of the 5V supply unfortunately touched pin 7.

  11. #11
    Quote Originally Posted by PaulStoffregen View Post
    Be careful with this. On many multimeters, beeper mode puts the meter into the lowest ohms range, where it feeds the highest test current through your circuitry. All multimeter ohms measurement involves injecting a test current and measuring the resulting voltage, but the highest ohms ranges use much lower / safer current.
    So I should watch out for putting too much current on the teensy pins through the continuity tests?

  12. #12
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    You'd never normally test for continuity through a chip, but between points supposedly on the same net. However if there
    is a break in continuity that can then result in the continuity test current being routed through a chip.

    Many multimeters use a 200mV ADC at the heart of the circuitry, so that for instance the 2000 ohm full-scale range
    involves 100µA test current, the 200 ohm range 1mA of test current. Normally that's not a problem as protection diodes
    conduct these low currents OK. However without protection diodes its not immediate obvious what the voltage compliance
    might be for various testers.

    My multimeter has back-to-back diode protection I think for ohms and continuity modes, the output voltage peaks at 0.65V or so
    but in diode-test mode the voltage is nearly 3V.

    Dedicated continuity testers however may be much more crude.

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