The Mega 2560 board has several services for speaking with a pc, One more board, or other microcontrollers. The ATmega2560 offers 4 hardware UARTs for TTL (5V) serial interaction. An ATmega16U2 (ATmega 8U2 over the revision 1 and revision two boards) on the board channels one particular of these around https://ligamega2591357.uzblog.net/5-simple-techniques-for-mega25-42189387