Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 4 of 4

Thread: Teensy 3.6 Hardware Serial Issue

  1. #1
    Junior Member
    Join Date
    Jun 2016
    Posts
    10

    Teensy 3.6 Hardware Serial Issue

    Have just run into the weirdest problem, this is the setting:

    I have a Teensy 3.6 with an FTDI connection to Serial3 (pins 7,8) (this shows up as Com25 on my computer - Win7-64)

    The following code is a minimum to demonstrate the problem:

    void setup()
    {
    Serial3.begin(19200);
    delay(10);
    }

    void loop()
    {
    int incomingByte;
    if (Serial3.available() > 0) {
    incomingByte = Serial3.read();
    Serial3.print("UART received:");
    Serial3.println(incomingByte, DEC);
    }
    }

    As long as the Teensy USB is connected, interaction with Serial3 via the FTDI works exactly as expected.

    If the Teensy USB is disconnected, all that happens is an irregular echo of the input with intermittent garbage characters.
    The problem is exactly the same on Serial1.

    I'm at a total loss to explain this and have a delivery date on the project (which must run on hardware serial) in the next few days.

    ANY suggestions would be greatly appreciated!

  2. #2
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Posts
    3,701
    How is it powered?

    I am assuming you are using a 3.3v ftdi adapter

  3. #3
    Junior Member
    Join Date
    Jun 2016
    Posts
    10
    Thanks for asking Kurt - yes, it is set for 3.3v (and verified by scope)
    However overnight I've found the issue - there was an obscure grounding problem with the FTDI board (plugging in the Teensy USB supplied the ground...)
    My apologies for thinking this could be a Teensy problem , consider the issue resolved.

  4. #4
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Posts
    3,701
    Glad you have it working!

Posting Permissions

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