- * This is a virtual serial port to soft-UART converter, for use on the Atmel XPLAIN boards. This project replaces the firmware\r
- * preloaded onto the XPLAIN's onboard AT90USB1287 microcontroller to act as a a UART-to-USB bridge between the device and the\r
- * host. When inserted, the device will enumerate as a regular COM port on the host, which can then be opened and data exchanged\r
- * between the XMEGA and Host as if the XMEGA was connected directly to the host's serial port.\r
+ * This project serves a dual purpose. When loaded into the USB AVR on the XPLAIN board, it will act as either a USB to Serial\r
+ * converter for the XPLAIN's hardware USART (at a speed of 9600 baud), or a PDI programmer for the XMEGA. This project replaces\r
+ * the firmware preloaded onto the XPLAIN's onboard AT90USB1287 microcontroller.\r
+ *\r
+ * When inserted, the JTAG port's TDI pin is read. If the pin is left high, the device will enumerate as a regular COM port on\r
+ * the host, which can then be opened and data exchanged between the XMEGA and Host as if the XMEGA was connected directly to\r
+ * the host's serial port. If the pin is pulled low, the device will enumerate as an AVRISP-MKII to the host, so that the XMEGA\r
+ * can be reprogrammed by AVRStudio or other compatible software such as avrdude.\r