It’s a significant update. The Arduino UNO and Arduino Mega 2560 update the Duemilanove and Mega respectively. They now use an ATMega8U2 instead of an FTDI USB to serial converter chip.

This project configure external memory as heap so that internal 8K memory is still used as before. You have to allocate the external memory before use. The sample program demo the usage. ATMEGA 2560 ...

According to MCP2003 datasheet, the LIN transceiver should be powered with 12V external power supply. On the other hand, the Arduino mega 2560 Master breadboard is powered with 5V from the PC’s USB ...