jim hamblen
Pushbutton counter demo showing switch contact bounce
Revision 0:996a0fc1fdea, committed 2011-09-20
- Comitter:
- 4180_1
- Date:
- Tue Sep 20 13:59:06 2011 +0000
- Commit message:
Changed in this revision
| main.cpp | Show annotated file Show diff for this revision Revisions of this file |
| mbed.bld | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Tue Sep 20 13:59:06 2011 +0000
@@ -0,0 +1,32 @@
+#include "mbed.h"
+
+DigitalOut myled(LED1);
+DigitalOut myled2(LED2);
+DigitalOut myled3(LED3);
+DigitalOut myled4(LED4);
+
+DigitalIn pb(p8);
+// SPST Pushbutton count demo using internal PullUp function
+// no external PullUp resistor needed
+// Pushbutton from P8 to GND.
+// Demonstrates need for debounce - will sometimes count more than once per button hit
+// This occurs on all switches due to mechanical contact bounce
+int main()
+{
+int count=0;
+int old_pb=1;
+int new_pb;
+ // Use internal pullup for pushbutton
+ pb.mode(PullUp);
+ // Delay for initial pullup to take effect
+ wait(.001);
+ while(1) {
+ new_pb = pb;
+ if ((new_pb==0) && (old_pb==1)) count++;
+ myled4 = count & 0x01;
+ myled3 = (count & 0x02)>>1;
+ myled2 = (count & 0x04)>>2;
+ myled = (count & 0x08)>>3;
+ old_pb = new_pb;
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Tue Sep 20 13:59:06 2011 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/63bcd7ba4912