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examples/isr.c

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+/*
+ * isr.c:
+ *	Wait for Interrupt test program - ISR method
+ *
+ *	How to test:
+ *	  Use the SoC's pull-up and pull down resistors that are avalable
+ *	on input pins. So compile & run this program (via sudo), then
+ *	in another terminal:
+ *		gpio mode 0 up
+ *		gpio mode 0 down
+ *	at which point it should trigger an interrupt. Toggle the pin
+ *	up/down to generate more interrupts to test.
+ *
+ * Copyright (c) 2013 Gordon Henderson.
+ ***********************************************************************
+ * This file is part of wiringPi:
+ *	https://projects.drogon.net/raspberry-pi/wiringpi/
+ *
+ *    wiringPi 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.
+ *
+ *    wiringPi 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 Lesser General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Lesser General Public License
+ *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <wiringPi.h>
+
+
+// What GPIO input are we using?
+//	This is a wiringPi pin number
+
+#define	BUTTON_PIN	0
+
+// globalCounter:
+//	Global variable to count interrupts
+//	Should be declared volatile to make sure the compiler doesn't cache it.
+
+static volatile int globalCounter = 0 ;
+
+
+/*
+ * myInterrupt:
+ *********************************************************************************
+ */
+
+void myInterrupt (void)
+{
+  ++globalCounter ;
+}
+
+
+/*
+ *********************************************************************************
+ * main
+ *********************************************************************************
+ */
+
+int main (void)
+{
+  int myCounter = 0 ;
+
+  if (wiringPiSetup () < 0)
+  {
+    fprintf (stderr, "Unable to setup wiringPi: %s\n", strerror (errno)) ;
+    return 1 ;
+  }
+
+  if (wiringPiISR (BUTTON_PIN, INT_EDGE_FALLING, &myInterrupt) < 0)
+  {
+    fprintf (stderr, "Unable to setup ISR: %s\n", strerror (errno)) ;
+    return 1 ;
+  }
+
+
+  for (;;)
+  {
+    printf ("Waiting ... ") ; fflush (stdout) ;
+
+    while (myCounter == globalCounter)
+      delay (100) ;
+
+    printf (" Done. counter: %5d\n", globalCounter) ;
+    myCounter = globalCounter ;
+  }
+
+  return 0 ;
+}