AnsweredAssumed Answered

FRDM-K22F, UART Rx (callback) Makes MQX Weird

Question asked by Jeffrey Graves on Apr 20, 2015

If I send enough characters to the UART, I can make MQX act weird*.


*MQX will stop running a task or...

*MQX will stop running more than one task or...

*MQX will run a task open loop, ignoring wait functions (ie OSA_TimeDelay()).


I have attached a "bare bones" project that reproduces this behavior.


This project uses a UART Rx data callback function.

(This simple project does not do anything with the received chars.)


This project targets the FRDM-K22F development board.


This project uses the following software:

KDS 2.0

KSDK 1.1.0




The project configuration is straight forward and what you get with PEx.


I have not taken any steps to install other interrupt handlers.


Steps to reproduce:


Comm settings: 115Kbps,N,8,1

Monitor the referenced I/O pins...

Repeatedly paste a string (~80 char) into a terminal app like Tera Term.

Eventually, the toggling I/O (square wave) will change indicating a MQX problem.

I have reproduced this problem with and without a Tera Term character delay (1ms).


Has anyone else seen this problem?


This issue is affecting the stability of a more complicated product.

Any feedback would be greatly appreciated.



Original Attachment has been moved to: