Application code


/*******************************************************************************
* keyboard-LED control application
* Copyright © 2013 Lukasz Kazmierczak
*******************************************************************************/

#include ...

#define KBD_BUTTONS     5U
#define LEDS            4U

#define LED_UP          1U
#define LED_DOWN        2U
#define LED_LEFT        0U
#define LED_RIGHT       3U

#define KBD_SEL         0U
#define KBD_UP          2U
#define KBD_DOWN        1U
#define KBD_LEFT        3U
#define KBD_RIGHT       4U

unsigned char _term=0;

static void signal_handler(int signal)
{

    if(signal == SIGTERM) {
        printf("Termination signal received\n");
        _term = 1;
    }
    else {
        // unsupported signal
    }
}

int main(int argc, char ** argv)
{
    int LED[LEDS]={0}, KBD[KBD_BUTTONS]={0};
    int ret = -1, i = 0;
    int kbdChkMsDelay = 100;
    struct timespec req = { .tv_sec=0, .tv_nsec= kbdChkMsDelay * 1000000 };

    char *LED_gpio[] =
        {
          "/dev/gpioF6",
          "/dev/gpioF7",
          "/dev/gpioF8",
          "/dev/gpioF9"
        };

    char *KBD_gpio[] =
        {
          "/dev/gpioG7",
          "/dev/gpioG8",
          "/dev/gpioG11",
          "/dev/gpioG13",
          "/dev/gpioG14"
        };

    if(argc != 1) {
        printf("%s.\n"\
        "\tapplication sets LEDs depend of JOY buttons state\n"\
        "\tsignal (\"kill -TERM \") kills the application\n", argv[0]);

        ret = 0;
    }
    else
    {
        signal(SIGTERM, signal_handler);

        for(i = 0; i < LEDS; i++)
            LED[i] = open(LED_gpio[i], O_WRONLY);

        for(i = 0; i < KBD_BUTTONS; i++)
            KBD[i] = open(KBD_gpio[i], O_RDONLY);

        if(LED[0]<0||LED[1]<0||LED[2]<0||LED[3]<0)
        {
            printf("can not open gpio port for writing.\n");
            return ret;
        }

        if(KBD[0]<0||KBD[1]<0||KBD[2]<0||KBD[3]<0||KBD[4]<0)
        {
            printf("can not open gpio port for reading.\n");
            return ret;
        }

        for(i = 0; i < LEDS; i++)
            write(LED[i], "0", 1);

        while(_term == 0)
        {
            for (i=0; i< KBD_BUTTONS; i++)
            {
                char buttonState = 0;
                read(KBD[i], &buttonState, 1);
                buttonState = '0' + (!(buttonState - '0'));

                // mapping buttons to LEDs
                switch(i) {
                    case KBD_UP:
                        write(LED[LED_UP], &buttonState, 1);
                        break;
                    case KBD_DOWN:
                        write(LED[LED_DOWN], &buttonState, 1);
                        break;
                    case KBD_LEFT:
                        write(LED[LED_LEFT], &buttonState, 1);
                        break;
                    case KBD_RIGHT:
                        write(LED[LED_RIGHT], &buttonState, 1);
                        break;
                    case KBD_SEL:
                        write(LED[LED_UP], &buttonState, 1);
                        write(LED[LED_DOWN], &buttonState, 1);
                        write(LED[LED_LEFT], &buttonState, 1);
                        write(LED[LED_RIGHT], &buttonState, 1);
                        break;
                    default: { /* button not supported */ }
                }
            }

            nanosleep(&req, NULL);
        }

        for(i = 0; i < LEDS; i++)
            write(LED[i], "0", 1);

        for(i = 0; i < LEDS; i++)
            close(LED[i]);

        for(i = 0; i < KBD_BUTTONS; i++)
            close(KBD[i]);

        ret = 0;
    }

    return ret;
}