Mysterious FRDM KL25Z Serial problem (solved)

11 May 2013


just want to report an error you can run into if you work with the Freedom board (FRDM KL25Z).

If you use pins PTA1 and PTA2 as outputs, your Serial communication might behave in a strange way. This is what happened to me: Serial.printf didn't give output, and flashing LEDs via PWM did produce strange output as I was able to read on Realterm. I solved the problem by using different pins for PWM output. However, I would suggest to include this information into the library description. In the detailled pinout map provided by Freescale, I see that UART RX and TX are located at these pins. Maybe this is the reason.

05 Jun 2013

I can confirm that this is the case.

I was using pins PTA1 and PTA2 as outputs, and they did not change state as expected when Serial communication was used with USBTX, USBRX.

I think a note about this should be visible in the handbook and possible a warning in the compiler when this combination appears.

07 Feb 2019


J'ai constaté le même souci, quand j'utilise TX/RX, je doit inversé TX et RX dans le compilateur pour faire fonctionner l'UART Correctement!


Cordialement, Antoine