Hi,
I just want the arduino sketch to print messages in the stdout. (by using printf() in the arduino IDE). so I commented out the "freopen" for stdout/stderr in the main function. but then many trace messages were printed in the screen. so I chose to disable the trace by trace_enable(0), then the problem occured....
I can work around my problem by "comment out the printf functions in trace_main() in trace.c" (the step 4 of the original post).
it is a so strange thing that the trace part will affect the ADC part.
Thanks
Jzd