Not working in freertos, are you sure it's threadsafe?

[mttbx]

I use this function in freertos. It makes freertos stucked in one task(thread, can't switch to other tasks). And when I call osDelay, it returns osErrorISR.

[mpaland]

I can assure you, that printf is perfectly threadsafe. It's heavily used and tested under freertos without any problems (in both preemption modes).
I think you have to check the stack size of your tasks, printf needs a configurable amount of size on the stack. If your task stack is not big enough, your freertos might crash, depending on your system config. Your mileage may vary.

[ledvinap]

@mttbx : You should also check actual output function, it may be not thread safe/callable from ISR context ...

[mttbx]

Thank you! I closed my issue because I found I may think it the wrong way.