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Embedded BLED112 - Virtual COM Port Emulation Stops Working

I ran into a problem with the BLED112 USB dongle’s COM emulation last night, and thought I would share my situation and solution with the world (as Googling the problem didn’t help).

I was talking to my BLE112 module using the BLED112 dongle (I think using BLEGUI) and all of a sudden the USB device was no longer recognized (as though the drivers had been erased). Windows asked me to re-install the drivers, which I did, however I no longer had a virtual COM port through which I could talk to my BLE112.

I tried the typical scenarios of uninstalling/re-installing drivers, removing and re-inserting the BLED112, etc… (I was desperate enough that I even tried… rebooting my computer… shudder).

The dongle appeared as a ‘Low Energy Device’, under the libUSB/WinUSB subsection of Device Manager, but I couldn’t get COM emulation back… I assumed I had bricked the device and was looking into purchasing another, but first I sent off an email to [‘the answer to all of my BlueGiga problems’], as he will now be known.

He suggested that the dongle might be stuck in DFU mode and that I could try to follow the instructions in section 4.4 (Commands Menu –> DFU) of the BLEGUI User Guide.

Flashing the BLED112

If you’re already stuck in DFU mode, then you can try the following steps to fix it using DFUTool (which updates the firmware of the BLE112 or BLED112 over USB).

  1. If Windows asks you to install the BLED112 driver, then do so. For me, the drivers are located in the following SDK directory: -1.1.0-55
  2. Build the USBCDC project in the SDK examples. From the -1.1.0-55directory, execute “.....exe project.xml”
  3. From the same directory, execute the following command to flash new firmware to the BLED112 dongle. Disclaimer: Do not remove the dongle or run out of power during this process, as you might brick the dongle. Also, this is the ONLY firmware image you want to flash to the dongle. “.....exe 2458:fffe out.hex af00 34%” As always, confirm that command with the most up-to-date BlueGiga documentation .

That process takes about 30 seconds (there is a percentage counter), after which the dongle should be back up and running with COM port emulation! Just to verify, remove and re-insert the device and then fire up BLEGUI or look in Device Manager to see if the BLED112 is recognized along with a COM port.

Hope that helps anyone who runs into this messy little situation!