#define SERIAL_PIN_DDR DDRD
#define SERIAL_PIN_PORT PORTD
#define SERIAL_PIN_INPUT PIND
#define SERIAL_PIN_MASK _BV(PD2)
#define SERIAL_PIN_INTERRUPT INT2_vect
#define SERIAL_SLAVE_BUFFER_LENGTH MATRIX_ROWS/2
#define SERIAL_MASTER_BUFFER_LENGTH 1