Microchip Technology application note AN956. Migrating Applications to USB from RS-232 UART with Minimal Impact on PC Software. The RS-232 serial emulation provides an easy migration path for applications moving from UART to USB. On the PC side it requires minimal software modification. On the embedded device side, the PIC18F 2455, 2550, 4455 and 4550 family of microcontrollers provides a simple hardware upgrade path from the PIC16C 745 and 765 as well as the PIC 18F XX2 family of devices. Library firmware that is user friendly APIs are included for convenience. Tutorial exercises are available as part of the CDC RS-232 emulation reference project. To download the complete application note for AN956 please visit the Microchip website at www.microchip.com/usb or search for AN956 in the upper right corner of the Microchip website. Code is also available.