test code for bridging between USB virtual serial and UART3(PTC17, PTC16).
This issue has been fixed on GitHub.
Serial Bridge between USB and UART3(PTC17, PTC16)
Why I share such a simple project?
There's an issue in serial format function of FRDM64K mbed library. Setting stop bit to 1 ends up stop bit 2 in serial controller register. See line 13 in main.cpp
uart3.format(8, Serial::None, 1>>1);
To set stop bit as 1, third parameter should be 0.
Hope this issue will be fixed future release.