UPS example added

C/pigeon-rb-ups/pigeon-rb-ups.c

@@ -0,0 +1,92 @@
+/*
+ * File:    pigeon-rb-ups.c
+ * Date:    7 September 2016
+ *
+ *  Pigeon RB300 UPS support
+ *
+ * Copyright (C) 2016 KRISTECH Krzysztof Kajstura
+ * www.pigeoncomputers.com
+ *
+ * Build:
+ * gcc -o pigeon-rb-ups pigeon-rb-ups.c -lwiringPi -pthread
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Lesser Public License for more details.
+ *
+ * You should have received a copy of the GNU General Lesser Public
+ * License along with this program.  If not, see
+ * <http://www.gnu.org/licenses/lgpl-3.0.html>.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <wiringPi.h>
+#include <stdbool.h>
+#include <semaphore.h>
+
+const int shutdown_pin = 27;
+static sem_t staticSem;
+int state;
+
+//
+// GPIO interrupt
+//
+void gpio_int(void) 
+{
+	usleep(100);  //minimal low state time is 100us		
+	state = digitalRead(shutdown_pin);
+
+	if (state == LOW) 
+	{
+		sem_post(&staticSem);
+	}
+}
+
+//
+//  main function
+//
+int main(void) 
+{
+	if (wiringPiSetupGpio() != 0)
+    {
+        printf("UPS service: wiringPiSetupGpio ERROR\n");
+		fflush(stdout);
+        return EXIT_FAILURE;
+    }
+
+	pinMode(shutdown_pin, INPUT);
+
+	if (wiringPiISR(shutdown_pin, INT_EDGE_FALLING, &gpio_int))
+    {
+        printf("UPS service: wiringPiISR ERROR\n");
+		fflush(stdout);
+        return EXIT_FAILURE;
+    }	
+
+	state = digitalRead(shutdown_pin);
+
+	if (state == LOW) 
+	{
+        printf("UPS service: shutdown signal active\n");
+		fflush(stdout);
+		system("shutdown -h now");
+		return 0;
+	}
+
+	while (1) 
+	{
+		sem_wait( &staticSem );
+		printf("UPS service: shutdown system\n");
+		fflush(stdout);
+		system("shutdown -h now");
+		return 0;
+	}
+}