Pushbutton demo using interrupts with switch contact bounce

Dependencies:   mbed

Revision:
0:7db73d1dc65f
Child:
1:6582c095e8d1
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Oct 06 00:18:44 2011 +0000
@@ -0,0 +1,39 @@
+#include "mbed.h"
+
+DigitalOut myled(LED1);
+DigitalOut myled2(LED2);
+DigitalOut myled3(LED3);
+DigitalOut myled4(LED4);
+
+InterruptIn pb(p8);
+// SPST Pushbutton count demo using interrupts
+// no external PullUp resistor needed
+// Pushbutton from P8 to GND.
+// A pb hit generates an interrupt and activates the interrupt routine
+// after the switch is debounced
+
+// Global count variable
+int volatile count=0;
+
+// pb Interrupt routine - is interrupt activated by a falling edge of pb input
+void pb_hit_interrupt (void) {
+    count++;
+    myled4 = count & 0x01;
+    myled3 = (count & 0x02)>>1;
+    myled2 = (count & 0x04)>>2;
+}
+
+int main() {
+    // Use internal pullup for pushbutton
+    pb.mode(PullUp);
+    // Delay for initial pullup to take effect
+    wait(.01);
+    // Attach the address of the interrupt handler routine for pushbutton
+    pb.fall(&pb_hit_interrupt);
+    // Blink myled in main routine forever while responding to pb changes
+    // via interrupts that activate pb_hit_interrupt routine
+    while (1) {
+        myled = !myled;
+        wait(.5);
+    }
+}
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