Serial port communicates with devices using serial protocole ( e.g. Arduino for hardware development, bluetooth, .. ). The same serial port is used for both input en output. Only short MIDI messages ( 3 bytes ) are exchanged, with first byte as status ( greater than 0x7F ), and second and third byte as data ( lower or equal than 0x7F ). The format can be binary ( paquest of 3 bytes ), or with ASCII lines starting with character equal ( e.g. for a note-on channel 1, pitch 79, velocity 106 : =804F6A ). Parameters of the serial port : 8 bit, 1 stop-bit, no parity, no flow control.