10 years, 5 months ago.

Using USBSerial on a custom board

I am trying to use this library with a custom board, powered with a KL25Z MCU (with D+ and D- connected correctly, with 33ohm resistors). I can load a program on my custom board with no problems - it has been tested with numerous programs.

When I load the USBSerial program, which I tested on the dev board, my pc doesn't seem to pickup a new USB CDC device like it does when I load it onto the dev board.

I am not a USB/Serial expert and so far this is what I've figured out/am assuming - please correct me if I'm wrong:

• When a fresh dev board (FRDM-KL25Z) is hooked up via the host USB port, a device called USB-UART shows up in device manager. I am assuming this is because Freescale has some pre-loaded code which is able to communicate some identifiers to the PC
• When I load the mbed firmware onto the dev board, the USB-UART doesn't show up anymore
• When I load the USBSerial sample code, with basic communication through the host USB and the programming USB, the host USB shows up as a USB CDC device on my pc
• I am able to create a serial link/pass through between the host USB and programming USB and see characters passed between two terminal windows
• When I load my custom board with the same sample code, with the programmer USB changed to a BT serial, I get nothing - even the test LED doesn't blink at the beginning of my program. This could be because the "USBSerial serial" object doesn't get constructed and execution halts/fails at that point.

I think there is some software problem and I have to configure the CDC headers to make it a "custom" board.

Any help/pointers are much appreciated! Thanks.

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