led_control_reference.c

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include "hwlib.h"
#include "socal/socal.h"
#include "socal/hps.h"
#include "socal/alt_gpio.h"
#include "../hps_0.h"

#define HW_REGS_BASE (ALT_STM_OFST)
#define HW_REGS_SPAN (0x04000000)
#define HW_REGS_MASK (HW_REGS_SPAN - 1)

int
main()
{
    void *virtual_base;
    int fd;
    int loop_count;
    int led_direction;
    int led_mask;
    void *h2p_lw_led_addr;

    // map the address space for the LED registers into user space so we can interact with them.
    // we'll actually map in the entire CSR span of the HPS since we want to access various registers within that span

    if ((fd = open( "/dev/mem", (O_RDWR|O_SYNC))) == -1) {
        printf("ERROR: could not open \"/dev/mem\"...\n");
        return 1;
    }
    virtual_base = mmap(NULL, HW_REGS_SPAN, (PROT_READ|PROT_WRITE),
                        MAP_SHARED, fd, HW_REGS_BASE);
    if (virtual_base == MAP_FAILED) {
        printf("ERROR: mmap() failed...\n");
        close(fd);
        return 1;
    }
	
    h2p_lw_led_addr = virtual_base
        + ((unsigned long)(ALT_LWFPGASLVS_OFST + MYPIO_0_BASE)
           & (unsigned long)(HW_REGS_MASK));

    // toggle the LEDs a bit
    int light_pattern = 0;
    loop_count = 0;
    led_mask = 0x01;
    led_direction = 0; // 0: left to right direction
    while (loop_count < 60) {
        // control led
        *(uint32_t *)h2p_lw_led_addr = ~led_mask; 

        // wait 100ms
        usleep(200*1000);

        // update led mask
        if (led_direction == 0) {
            if (light_pattern == 0){ 
                led_mask <<= 2;
                light_pattern = 1;
            }else{
                led_mask >>= 1;
                light_pattern = 0;
            }
            if (led_mask == (0x01 << (7)))
                {
                    led_direction = 1;
                    light_pattern = 0;
                    usleep(100*1000);
                }
        } else {
            if (light_pattern == 0){ 
                led_mask >>= 2;
                light_pattern = 1;
            }else{
                led_mask <<= 1;
                light_pattern = 0;
            }
            if (led_mask == 0x01) {
                led_direction = 0;
                light_pattern = 0;
                loop_count++;
                usleep(100*1000);
            }
        }
    } // while

    // clean up our memory mapping and exit
    if (munmap( virtual_base, HW_REGS_SPAN ) != 0) {
        printf("ERROR: munmap() failed...\n");
        close(fd);
        return 1;
    }
    close(fd);
    return 0;
}