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Hi guys,

I think I may have found a bug in the FastSerial Library...

In trying to get the CLI test to perform a XBee test, I found that no data was being written to the telemetry port, after checking my APM_Config.h settings, my XBee setup and hooking up my osciloscope up to the telemetry transmit pin, I turned to the code to start debugging...

I found that in the XBee test routine the line that should transmit the data read

Serial3.printf_P(PSTR("0123456789:;<=>?@ABCDEFGHIJKLMNO\n"));

and although this line was clearly directing output to serial port 3, the data was in fact coming back on serial port 1, I also found that using Serial3.printf instead worked fine.

I therefore looked in the FastSerial Library source, where these two functions are declared on the base class and found that in the printf_P function, the code was passing stdout instead of a pointer the local _fd member variable to the stdio vfprintf_P function (while in the printf routine this code was correct)

So, in the prinf_P routine, I replaced the line

i = vfprintf_P(stdout, fmt, ap);

with

i = vfprintf_P(&_fd, fmt, ap);

and this seemed to solve all my problems.

Since stdout seems to default to serial port 1, this would not have caused a problem when using Serial.printf_P and therefore would also only have affected the APM with it's multiple ports.

Any thoughts or collaborations on my findings, my c++ is a bit rusty so wanna be sure I am on the right track.

Thanks

Chris

London