USB serial debugging question

06 Oct 2012

Hi, can you help me with a new problem I am having using the serial USB debugging facility.

I have two mbeds, one soldered into a pcb with interface chips etc., the other just a naked module.

I have used the serial debug for many months without issue so are happy that I understand the setup. Today my soldered in mbed nolonger generates any serial debug output, Windows XP does not see the port (usually 10).

The standalone mbed does generate debug output and Windows sees the mbed on port 10.

The soldered in mbed runs different code, but the debug bits look the same as the standalone module. I can't run the same code in the standalone module as it needs the support chips to function.

I shall try downloading some temporary simplified diagnostics code to both modules to see what happens, but as the coding requirements are so simple for serial debug, what can I be doing wrong?

What actually makes Windows see the com port?

All other aspects of my code are working fine which includes ADCs, DAC's, LCD, RTC, USB file reading and writing, timing etc., and the serial debug had worked on earlier code development versions on the soldered in module.

Currently Flash is at 6% and RAM at 79% used.

08 Oct 2012

Simplifying my question above....

What actually makes Windows see the com port? Is it the mbed code Serial pc(USBTX, USBRX);

If it is not the above code, what is it and also what could prevent the Win XP seing the com port?

Thanks

08 Oct 2012

Can you see the mbed as a drive ?? I know for the serial port part you need the mbed drivers installed or only the drive shows up , no virtual com. It's the Mbed magic chip that does the virtual com part

08 Oct 2012

hi, for the problem of finding com port 10 in win xp, you can try to give it a lower com number 9 or so, because win xp has some problems to communicate with a higer port number than 9.

08 Oct 2012

Thanks for your comments.

The mbed works perfectly in programming, also my mbed reads configuration data from drive (created on the PC)and also creates and writes data to a file on the drive (which is imported into Excel) without any problems.

If I use a different mbed the serialUSB comms appear and all works well with the serialUSB diagnostics, hence PC end seems OK.

The current mbed seems to function correctly in all respects except this serialUSB aspect.

I shall try downloading a smaller program with simple serial diagnostics running tomorrow to see if that works. As said in my first post this non-functioning serialUSB diagnostics was not an issue in the past and was used extensively while learning and coding the mbed.

09 Oct 2012

I believe you need to install the mbed windows serial driver separately for each mbed module. The memory stick part is recognised automatically by windows. So just plug in the mbed and run the serial driver executable to install it on your PC.

09 Oct 2012

Hi Wim,

Many thanks, you are correct issue solved. The two mbeds appear at different port numbers 10 and 18 and you have to remember to restart the terminal prog (or search for ports) when swapping mbeds, but that's all.

Thanks for you help.