Changes between Version 14 and Version 15 of gpio

Timestamp:

07/16/2019 10:33:20 PM (5 years ago)

Author:

Cale Collins

Comment:

changed example code for polling without interupt

gpio

@@ -261 +261 @@
 #include <sys/stat.h>
 
-/* seconds to block waiting for edge
- *  - this also defines the interval between calls if button is held down
- */
-#define BLOCK_TIME 5
-/* seconds held for reboot */
-#define REBOOT_TIME 15
-/* seconds before press-and-release count is cleared */
-#define MIN_REST_TIME 2
-
-/* called when a gpio changes value
- * @value - 0 is low, 1 is high
- *
- * The GSC pushbutton has an internal pullup, thus a 'button' should be
- * normally open, and when pressed should short to ground. Therefore a 0
- * is 'down', and a 1 is 'up'
- */
-time_t held_time = 0; /* num seconds button held down */
-time_t last = 0; /* last event time */
-int num_releases = 0; /* number of successive press-and-release events */
-void gpio_change(int gpio, int value)
-{
-        time_t now = time(NULL);
-
-        printf("gpio%d: %d last=%ld\n", gpio, value, (long)(now - last));
-        if (!value) { /* down */
-                long held;
-                if (!held_time)
-                        held_time = now;
-
-                held = (long)(now - held_time);
-                printf("held=%ld\n", held);
-
-                /* if held for more than REBOOT_TIME seconds */
-                if (held >= REBOOT_TIME) {
-                        printf("Powering system down\n");
-#ifdef __ANDROID__
-                        /* will perform a safe unmount prior to shutdown */
-                        android_reboot(ANDROID_RB_POWEROFF, 0, 0);
-#else
-                        reboot(RB_POWER_OFF);
-#endif
-                        while (1);
-                }
-        } else { /* up */
-                /* cancel held time counter */
-                held_time = 0;
-                /* increment or reset num_releases */
-                if (now - last < MIN_REST_TIME) {
-                        num_releases++;
-                        printf("count=%d\n", num_releases);
-
-                        /* perform something on number of presses? */
-            
-                        printf("reset count\n");
-                        num_releases = 0;
-                }
-
-                last = time(NULL);
-        }
-}
-
 
 int main(int argc, char **argv)
@@ -366 +305 @@
                 fdset.events = POLLPRI;
                 fdset.revents = 0;
-                if ((c = poll(&fdset, 1, BLOCK_TIME*1000)) < 0) {
+                if ((c = poll(&fdset, 1, -1)) < 0) {
                         perror("poll() failed");
                         break;
                 }
 
-                //if (fdset.revents & POLLPRI)
-                {
-                        /* show gpio value */
-                        /* Note that both an lseek and read are necessary
-                         * in order to clear the interrupt detected by poll
-                         */
-                        lseek(fdset.fd, 0, SEEK_SET);
-                        rz = read(fdset.fd, buf, sizeof(buf));
-                        buf[rz ? rz - 1 : 0] = 0;
-                        gpio_change(gpio, atoi(buf));
-                }
+                /* show gpio value */
+                /* Note that both an lseek and read are necessary
+                 * in order to clear the interrupt detected by poll
+                 */
+                usleep (100000); /*100ms delay to debounce*/
+                lseek(fd, 0, SEEK_SET);
+                rz = read(fd, buf, sizeof(buf));
+                buf[rz ? rz - 1 : 0] = 0;
+                printf("%d: ret=%d gpio%d=%d rz=%d\n", (int)time(NULL),c, gpio, atoi(buf),
+                                        rz);
         }
         close(fd);
@@ -387 +325 @@
         return 0;
 }
-
 }}}