Purpose: GPIO port widths, masks and pull-ups.

Namespace: atmega2560::gpio.

#include <atmega2560/GPIO.h>
 
namespace mcu = atmega2560;
 
static_assert(mcu::gpio::port_count == 11, "ATmega2560 GPIO definition");

Port map

Port	GPIO bits
A, B, C, D, E, F, H, J, K, L	0–7
G	0–5

The chip has 86 general-purpose I/O lines. GPIO pins shared with external memory, JTAG, the crystal, or serial peripherals may be unavailable to general GPIO in a given board configuration.

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

Source: ATmega2560 datasheet (DS40002211A).