Sample Code/C/LED

From GumstixDocsWiki

/* This program writes a byte with a shifting bit to                   */
/* GPIO 59, 60, 61, 62, 81, 82, 83, 84                                 */
/* These bits are available on the STUART 20 pin solder pads           */
/* by Tim Crawford                                                     */

#include <stdio.h>
#include <time.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#define MAP_SIZE 4096
#define MAP_MASK ( MAP_SIZE - 1 )
#define GAFR1_U 0x40E00060
#define GAFR2_U 0x40E00068
#define GPDR1 0x40E00010
#define GPDR2 0x40E00014
#define GPCR1 0x40E00028
#define GPCR2 0x40E0002C
#define GPSR1 0x40E0001C
#define GPSR2 0x40E00020

typedef unsigned int u32;

void *map, *regaddr;
static void putmem(u32 addr, u32 val)
{
   regaddr = map + (addr & MAP_MASK);
   *(u32*) regaddr = val;
}
static int getmem(u32 addr)
{
   u32 val;

   regaddr = map + (addr & MAP_MASK);
   val = *(u32*) regaddr;
   return val;
}
void clearbits(unsigned char uc)
{
    putmem(GPCR1, (uc & 0x0F) << 27);
    putmem(GPCR2, (uc & 0xF0) << 13);
}
void setbits(unsigned char uc)
{
    putmem(GPSR1, (uc & 0x0F) << 27);
    putmem(GPSR2, (uc & 0xF0) << 13);
}
void setlights(unsigned char uc)
{
    clearbits(~uc);
    setbits(uc);
}
int main( int argc, char **argv )
{
    unsigned int i;
    int fd;
    unsigned char lights;
    struct timespec tv;
    unsigned char bulb[8] = {0, 1, 2, 3, 4, 5, 6, 7};
    unsigned char patt[8];

    fd = open("/dev/mem", O_RDWR | O_SYNC);
    if (fd<0) {
        perror("open(\"/dev/mem\")");
        exit(1);
    }
    map = mmap(0,
              MAP_SIZE,
              PROT_READ | PROT_WRITE,
              MAP_SHARED,
              fd,
              0x40E00000 & ~MAP_MASK
             );
    if (map == (void*)-1 ) {
       perror("mmap()");
       exit(1);
    }

    /* Set alternate function to GPIO */
    i = getmem(GAFR1_U);
    i &= 0x87FFFFFF;
    putmem(GAFR1_U, i);
    i = getmem(GAFR2_U);
    i &= 0xFFFFE0;
    putmem(GAFR2_U, i);

    /* Set the GPIO direction */
    i = getmem(GPDR1);
    i |= 0x78000000;
    putmem(GPDR1, i);
    i = getmem(GPDR2);
    i |= 0x001E0000;
    putmem(GPDR2, i);

    printf( "Mello World\n" );
    for (i = 0; i < count; i++){
      nanosleep(&tv, &tv);
      setlights(lights);
      lights <<= 1;
      if (!lights)
        lights = 1;
      printf("i = %d lights = %X\n", i, lights);
    };

    munmap(0,MAP_SIZE);
    return 0;
}