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

Thread: PS2Keyboard Library - Teensy 3.6 / LC

  1. #1
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany NRW
    Posts
    4,508

    PS2Keyboard Library - Teensy 3.6 / LC

    Hi,

    First, I don't know the output-Voltage of a PS/2 keyboard if it is powered with 5V.
    But, If it is 5V - you might want to upate this page: https://www.pjrc.com/teensy/td_libs_PS2Keyboard.html for not 5 Volt tolerant Teensys

  2. #2
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany NRW
    Posts
    4,508
    Quote Originally Posted by Frank B View Post
    Hi,

    First, I don't know the output-Voltage of a PS/2 keyboard if it is powered with 5V.
    But, If it is 5V - you might want to upate this page: https://www.pjrc.com/teensy/td_libs_PS2Keyboard.html for not 5 Volt tolerant Teensys
    Do I need a level shifter for the T3.6, or does it work without ?

  3. #3
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Posts
    6,829
    I did a search and didn't find one that told me for sure: https://www.electronicspoint.com/thr...o-cmos.124642/

    Some showed/suggested it was needed to level shift - others not?

    PS/2 wouldn't be wireless - but I do have a new PS/2 keyboard or two.

  4. #4
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany NRW
    Posts
    4,508
    I've added a USB Connector to my VGA Board - Since these green PS2->USB adapters are only wires - and not really needed - this works. I've used 3.3Volt as power.
    This works - but.. does it work with every PS2 Keyboard ?
    Tim: If you have some room on your VGA board.. can you add a USB connector for testing ? :-) I've just used Teensy pins 0 and 1

    It would be really useful if Paul could say something

  5. #5
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    Posts
    6,829
    I pulled the badly oriented VGA connector from my PCB - when I rebuild with a fresh VGA connector I'll add a PS2 ( on pin 0&1 with 3V3 ) as I think SparkFun sent me 1 or 2 once.

    Indeed that PJRC page says it works with T_3.6 - maybe the PS2 output is at 3.3V levels and Paul knows - but my quick search didn't confirm that.

  6. #6
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany NRW
    Posts
    4,508
    If not, you're risking your Teensy. I'd use 3.3 volts as power if we didn't have an answer.
    Last edited by Frank B; 09-21-2017 at 09:24 PM.

  7. #7
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany NRW
    Posts
    4,508
    Searching through the net, I learned that some keyboards seem to have a pullup on the data-line. So they pull-up to 5 Volt. If that pull-up it strong enough, there's a risk for the not 5V tolerant parts in my opinion. Hopefully, users read this before they add a PS/2 keyboard.
    Last edited by Frank B; 09-23-2017 at 07:59 PM.

  8. #8
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    18,300
    I've updated the PS2 Keyboard page with a caution note and link to Adafruit's level shifter 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
  •