GPIOs

Registers

struct gpio_register_map

This struct maps the registers of the GPIOs. The names of the struct members correspond to the registers from the Datasheet:

struct gpio_register_map {
        uint32_t FSEL[6];
        uint32_t: 32;
        uint32_t SET[2];
        uint32_t: 32;
        uint32_t CLR[2];
        uint32_t: 32;
        uint32_t LEV[2];
        uint32_t: 32;
        uint32_t EDS[2];
        uint32_t: 32;
        uint32_t REN[2];
        uint32_t: 32;
        uint32_t FEN[2];
        uint32_t: 32;
        uint32_t HEN[2];
        uint32_t: 32;
        uint32_t LEN[2];
        uint32_t: 32;
        uint32_t AREN[2];
        uint32_t: 32;
        uint32_t AFEN[2];
        uint32_t: 32;
        uint32_t PUD;
        uint32_t PUDCLK[2];
// BCM2711 only
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t: 32;
        uint32_t PUPPDN[4];
};

extern volatile struct gpio_register_map *GP

GP = (volatile struct gpio_register_map *)gpio_base_ptr;

By using this struct, the registers of the GPIOs can be accessed like this GP->SET[0].

Enums

Pin functions

This enum holds the values for the various pin functions:

enum {
        INPUT, OUTPUT, ALT0, ALT1, ALT2, ALT3, ALT4, ALT5
};

Pullup / -downs

This enum holds the values for the states of the pullups / -downs:

enum {
        PUD_DISABLE, PUD_DOWN, PUD_UP
};

Functions

int gpio_map(void)

This function maps the GPIO registers. It calls peripheral_map() with the values GPIO_OFFSET and GPIO_SIZE. On error -1 is returned.

void gpio_unmap(void)

This function unmaps the GPIOs.

void gpio_func(uint32_t pin, int function)

This function sets the pin pin to the pin function function.

void gpio_set(uint32_t pin)

Set the pin pin.

void gpio_clr(uint32_t pin)

Clear the pin pin.

uint32_t gpio_tst(uint32_t pin)

Test the pin pin. This function returns 0 or false when the pin is low and non-zero if the pin is high.

void gpio_pud(uint32_t pin, int pud)

Use the pullup / -down functionality pud on the pin pin.

void gpio_inp(uint32_t pin)

Make pin pin an input.

void gpio_out(uint32_t pin)

Make pin pin an output.