mirror of https://github.com/CIRCL/Circlean
82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#include <unistd.h>
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/* GPIO registers address */
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#define BCM2708_PERI_BASE 0x20000000
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#define GPIO_BASE (BCM2708_PERI_BASE + 0x200000) /* GPIO controller */
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#define BLOCK_SIZE (256)
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/* GPIO setup macros. Always use GPIO_IN(x) before using GPIO_OUT(x) or GPIO_ALT(x,y) */
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#define GPIO_IN(g) *(gpio+((g)/10)) &= ~(7<<(((g)%10)*3))
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#define GPIO_OUT(g) *(gpio+((g)/10)) |= (1<<(((g)%10)*3))
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#define GPIO_ALT(g,a) *(gpio+(((g)/10))) |= (((a)<=3?(a)+4:(a)==4?3:2)<<(((g)%10)*3))
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#define GPIO_SET(g) *(gpio+7) = 1<<(g) /* sets bit which are 1, ignores bit which are 0 */
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#define GPIO_CLR(g) *(gpio+10) = 1<<(g) /* clears bit which are 1, ignores bit which are 0 */
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#define GPIO_LEV(g) (*(gpio+13) >> (g)) & 0x00000001
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#define GPIO_4 4
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int mem_fd;
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void *gpio_map;
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volatile uint32_t *gpio;
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int main(int argc, char* argv[])
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{
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int ret;
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int i;
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/* open /dev/mem */
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mem_fd = open("/dev/mem", O_RDWR|O_SYNC);
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if (mem_fd == -1) {
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perror("Cannot open /dev/mem");
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exit(1);
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}
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/* mmap GPIO */
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gpio_map = mmap(NULL, BLOCK_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, mem_fd, GPIO_BASE);
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if (gpio_map == MAP_FAILED) {
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perror("mmap() failed");
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exit(1);
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}
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/* Always use volatile pointer! */
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gpio = (volatile uint32_t *)gpio_map;
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GPIO_IN(GPIO_4); /* must use GPIO_IN before we can use GPIO_OUT */
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GPIO_OUT(GPIO_4);
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//Turn on led
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while (1) {
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//printf("Enable LED\n");
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GPIO_SET(GPIO_4);
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usleep(1000000);
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//printf("Disable GPIO\n"); // Does not seem to work?
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//GPIO_CLR(GPIO_4);
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//usleep(1000000);
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}
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/* Free up ressources */
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/* munmap GPIO */
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ret = munmap(gpio_map, BLOCK_SIZE);
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if (ret == -1) {
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perror("munmap() failed");
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exit(1);
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}
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/* close /dev/mem */
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ret = close(mem_fd);
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if (ret == -1) {
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perror("Cannot close /dev/mem");
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exit(1);
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}
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return EXIT_SUCCESS;
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}
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