Hi @tl007,
Can you define FMSTR_DEBUG_TX in "freemaster_cfg" header file "#define FMSTR_DEBUG_TX 1". This option instructs the driver to periodically transmit test frames out on the selected communication interface. If you connect with a RS232 terminal such as termite you should see test data "+©W" coming from the board.
If this does not work make sure that you are able to send / receive data via the serial line using standard SDK functions, again using a RS232 terminal. In this case freemaster driver should be disabled "#define FMSTR_DISABLE 1" to not interfere with SDK send / receive functions.
We can further investigate this issue once you confirm that there are no issues with plain serial communication.
Regards,
Iulian