Bug in FastSerial Library?

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

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –

Replies

  • Thank for all the help guys... much appreciated.
  • Developer
    I'm pretty sure that DrZiplock fixed this bug a day or two ago.
    https://code.google.com/p/arducopter/source/detail?r=685

    Hopefully you'll see that if you download the latest version of the code from SVN.
  • Oh - also just found another fix/tip....

    In the XBee test code (the test_xbee function in test.pde)....

    Removing the \n from the string being transmitted will make the data match up perfectly with the data packets sent from the X-CTU software... the new line of code will look like:

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

    Therefore the X-CTU range test results will now show 100% results and not average around 50%

    Hope this helps....

    Chris
    London
  • Admin
    Chris,

    Nice work! Maybe you should file a bug report on the APM official repository: http://code.google.com/p/ardupilot-mega/issues/list

    Regards,
    TCIII
This reply was deleted.

Activity

Neville Rodrigues liked Neville Rodrigues's profile
Jun 30
Santiago Perez liked Santiago Perez's profile
Jun 21
More…