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

Thread: Teensy 4.0 Program and On/Off pins

  1. #1

    Teensy 4.0 Program and On/Off pins

    I've ordered a Teensy 4.0 which will arrive in a couple of weeks but am designing a PCB to put it on already.

    But I've failed to find anything in the documentation online saying which way up the Program and On/Off pins are - active high or active low. Could somebody let me know as I obviously can't send the PCB off to JLCPCB until I'm sure I have them the right way up.

  2. #2
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Posts
    6,085
    Both signals I believe are setup that if you were to hook them up to a button, you would connect the other side of the button to ground... At least that is how my boards work...

  3. #3
    Great thanks. I assumed they would be /Program and /Off but it would have helped if it was documented somewhere.

  4. #4
    Senior Member
    Join Date
    May 2015
    Location
    San Francisco
    Posts
    219
    I see that the program pin seems to work as it did in T3.2 and T3.6, but I don't see how to do a system reset with the on/off pin. Is this possible? Or is there another way to do a reset electrically?

  5. #5
    Senior Member+ MichaelMeissner's Avatar
    Join Date
    Nov 2012
    Location
    Ayer Massachussetts
    Posts
    3,481
    Quote Originally Posted by blackketter View Post
    I see that the program pin seems to work as it did in T3.2 and T3.6, but I don't see how to do a system reset with the on/off pin. Is this possible? Or is there another way to do a reset electrically?
    You connect the on/off pin to ground for 4-5 seconds, and the Teensy will turn off. Once you disconnect the Teensy on/off pin from ground and connect it again to ground for 1-2 seconds, the Teensy will turn back on. So it isn't a reset like the 3.5/3.6 had with their reset pin (in the DAC position) or the 3.1/3.2 had with the reset pads underneath the Teensy where connecting the pin to ground would reset it immediately.

  6. #6
    Junior Member
    Join Date
    Oct 2015
    Posts
    3
    I would like to have a reset function on the T4 like T3.2/3.6 where I had the pin tied to an external watchdog timer IC. Is there a way to do this on T4? The ON/OFF pin is a little hard to manage by holding the pin down for 5 seconds and then again by 2 seconds. If I were to hotwire across the reset button on the top of the board, can someone tell me which pins I should solder to?

  7. #7
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany NRW
    Posts
    6,163
    Looking at the schematic, i think it is maybe Pin 9 on the MKL chip.
    With TD1.50 the watchdogs work, and a software-reset is possible, too.
    For a faster switch-off, there is a library T4_Powerbutton on my github (just use a empty callback, google this forum)

  8. #8
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Posts
    6,085
    Quote Originally Posted by ghjmaui View Post
    I would like to have a reset function on the T4 like T3.2/3.6 where I had the pin tied to an external watchdog timer IC. Is there a way to do this on T4? The ON/OFF pin is a little hard to manage by holding the pin down for 5 seconds and then again by 2 seconds. If I were to hotwire across the reset button on the top of the board, can someone tell me which pins I should solder to?
    Note: Paul mentioned in the earlier thread on larger version of Teensy: https://forum.pjrc.com/threads/58028...l=1#post219038
    That the Rest pin would not go onto T4.1 as it would require some significant changes...

    So personally I would be careful about just shorting out pins...

Posting Permissions

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