TWI.h

Purpose: Two-wire serial interface characteristics.

Namespace: atmega2560::twi.

SCL is PD0 and SDA is PD1; both pins also support external interrupt inputs INT0 and INT1.

#include <atmega2560/TWI.h>
 
namespace mcu = atmega2560;
 
static_assert(mcu::twi::scl_pin_value == 0x30, "ATmega2560 TWI definition");

These are hardware definitions, not runtime register access or initialization.

Source: ATmega2560 datasheet (DS40002211A).