Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 8 of 8

Thread: T3.6 - 1.6v instead of 3.3v

  1. #1
    Senior Member
    Join Date
    Apr 2019
    Posts
    184

    T3.6 - 1.6v instead of 3.3v

    I have a T3.6 that has been powered up with some connections unplugged

    the board illuminates the led on startup but faintly

    I have checked the voltage - there is only 1.6v

    there is no serial communication

    can i add 3.3 v externally to the 3.3 pin ?

    can the voltage reg on the board be replaced

    any other sugestions greatfully accepted - I may struggle to get a replacement board in time for a deadline !

  2. #2
    Senior Member PaulS's Avatar
    Join Date
    Apr 2015
    Location
    Netherlands
    Posts
    865
    If the output of the 3V3 regulator shows only 1.6V, the regulator may not be dead at all but just running into its current limiter.
    Please check whether there is a heavy load on the 3V3 pin. The 3V3 output of the Teensy 3.6 can only supply 250mA maximum.

    Are you powering the T3.6 by USB? Is there any heavy load on the 5V pin?

    Paul

  3. #3
    Senior Member
    Join Date
    Apr 2019
    Posts
    184
    Quote Originally Posted by PaulS View Post
    If the output of the 3V3 regulator shows only 1.6V, the regulator may not be dead at all but just running into its current limiter.
    Please check whether there is a heavy load on the 3V3 pin. The 3V3 output of the Teensy 3.6 can only supply 250mA maximum.

    Are you powering the T3.6 by USB? Is there any heavy load on the 5V pin?

    Paul
    Hi Paul,

    Thanks for the reply


    with the T3.6 powered by usb and unplugged from anything the 3.3v pin is just under 2 volts

    can the board be repaired ? can i use an external 3.3v reg to power the 3.3v pin ?

  4. #4
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    26,818
    From the small amount of info given so far, I'm afraid the odds of repair are probably not good. But that is based on some guesswork.

    Voltage regulators rarely fail. When you have less than 3.3V from the 3.3V regulator, the cause is almost always something else has failed and is drawing too much current. The voltage regulator has safety features to limit its current and maximum temperature by automatically reducing the output when the load is too much. When you see less than the correct voltage, typically it's because the regulator is working properly and those safety features are coming into play.

    However, one well known situation where you get not enough voltage output is when you have not enough voltage input. Normally this happens when the power source is a nearly dead battery or an unpowered USB hub. You can pretty easily check by just measuring the VUSB or VIN voltage. If it's something like only 1.9 volts, then of course you'd expect the regulator to only be able to output 1.6 volts.

    But if you have a solid 5 volts input and the regulator is only giving 1.6 volts output, and especially if it's running really hot, that's a sure sign something is drawing too much current.

    If you get lucky, that "something" might be a circuit you can disconnect and troubleshoot. If you're unlucky, it's quite possible the main processor is damaged.

    Which of these scenarios applies to your situation, I can not know. Rather than a lot of back-and-forth questions, hopefully this longer explanation which tries to cover most cases helps.

  5. #5
    Senior Member
    Join Date
    Apr 2019
    Posts
    184
    hi Paul - thank you for the prompt reply

    it is probably not worth the effort trying to get this board repaired

    is the T4.1 compatible pin for pin ?

  6. #6
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    26,818
    Teensy 4.1 has many pins in common with Teensy 3.6, but not all are identical.




  7. #7
    Senior Member
    Join Date
    Apr 2019
    Posts
    184
    Is there a way to slow the t4.1 down to the same speed as the t3.6 ?

    I am using the board to count encoder pulses and perform pid motor control

    The timing seems to be wrong with the T4.1

    Can you recommend a dealer in the uk with stock of t3.6 / 4.1

  8. #8
    Quote Originally Posted by Gadget999 View Post
    Is there a way to slow the t4.1 down to the same speed as the t3.6 ?
    You can set the CPU Frequency from the Tools menu of Arduino IDE. Nominal frequency for T3.6 is 180 MHz. For the T4.1, the closest setting is 150 MHz, so you could try that. Do your PID loops run at a fixed frequency (using a timer) or do they run "as fast as possible" given the CPU speed?

Posting Permissions

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