I have firmware in C for a MikroElectronika "PIC Clicker" development board using a PIC18F47J53. It includes MikroE's USB library for CDC (USB RS232 emulation). Works fine on Windows, but on a Mac (e.g. OS-X 10.9.5) it registers a /dev/[login to view URL] port but doesn't communicate (hangs on host write to board). On Linux, it creates a /dev/ttyACMXX port and receives data from the host but doesn't transmit. I need to either adjust the firmware, or configure the host, or both, so that it works on the Mac. Linux isn't required, just another data point.