Teensy 3.6 Hardware Serial Issue

B

buhlerl

Member
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!
 
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.
 
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