jim hamblen
Pushbutton demo using interrupts with switch contact bounce
main.cpp@0:7db73d1dc65f, 2011-10-06 (annotated)
- Committer:
- 4180_1
- Date:
- Thu Oct 06 00:18:44 2011 +0000
- Revision:
- 0:7db73d1dc65f
- Child:
- 1:6582c095e8d1
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| 4180_1 | 0:7db73d1dc65f | 1 | #include "mbed.h" |
| 4180_1 | 0:7db73d1dc65f | 2 | |
| 4180_1 | 0:7db73d1dc65f | 3 | DigitalOut myled(LED1); |
| 4180_1 | 0:7db73d1dc65f | 4 | DigitalOut myled2(LED2); |
| 4180_1 | 0:7db73d1dc65f | 5 | DigitalOut myled3(LED3); |
| 4180_1 | 0:7db73d1dc65f | 6 | DigitalOut myled4(LED4); |
| 4180_1 | 0:7db73d1dc65f | 7 | |
| 4180_1 | 0:7db73d1dc65f | 8 | InterruptIn pb(p8); |
| 4180_1 | 0:7db73d1dc65f | 9 | // SPST Pushbutton count demo using interrupts |
| 4180_1 | 0:7db73d1dc65f | 10 | // no external PullUp resistor needed |
| 4180_1 | 0:7db73d1dc65f | 11 | // Pushbutton from P8 to GND. |
| 4180_1 | 0:7db73d1dc65f | 12 | // A pb hit generates an interrupt and activates the interrupt routine |
| 4180_1 | 0:7db73d1dc65f | 13 | // after the switch is debounced |
| 4180_1 | 0:7db73d1dc65f | 14 | |
| 4180_1 | 0:7db73d1dc65f | 15 | // Global count variable |
| 4180_1 | 0:7db73d1dc65f | 16 | int volatile count=0; |
| 4180_1 | 0:7db73d1dc65f | 17 | |
| 4180_1 | 0:7db73d1dc65f | 18 | // pb Interrupt routine - is interrupt activated by a falling edge of pb input |
| 4180_1 | 0:7db73d1dc65f | 19 | void pb_hit_interrupt (void) { |
| 4180_1 | 0:7db73d1dc65f | 20 | count++; |
| 4180_1 | 0:7db73d1dc65f | 21 | myled4 = count & 0x01; |
| 4180_1 | 0:7db73d1dc65f | 22 | myled3 = (count & 0x02)>>1; |
| 4180_1 | 0:7db73d1dc65f | 23 | myled2 = (count & 0x04)>>2; |
| 4180_1 | 0:7db73d1dc65f | 24 | } |
| 4180_1 | 0:7db73d1dc65f | 25 | |
| 4180_1 | 0:7db73d1dc65f | 26 | int main() { |
| 4180_1 | 0:7db73d1dc65f | 27 | // Use internal pullup for pushbutton |
| 4180_1 | 0:7db73d1dc65f | 28 | pb.mode(PullUp); |
| 4180_1 | 0:7db73d1dc65f | 29 | // Delay for initial pullup to take effect |
| 4180_1 | 0:7db73d1dc65f | 30 | wait(.01); |
| 4180_1 | 0:7db73d1dc65f | 31 | // Attach the address of the interrupt handler routine for pushbutton |
| 4180_1 | 0:7db73d1dc65f | 32 | pb.fall(&pb_hit_interrupt); |
| 4180_1 | 0:7db73d1dc65f | 33 | // Blink myled in main routine forever while responding to pb changes |
| 4180_1 | 0:7db73d1dc65f | 34 | // via interrupts that activate pb_hit_interrupt routine |
| 4180_1 | 0:7db73d1dc65f | 35 | while (1) { |
| 4180_1 | 0:7db73d1dc65f | 36 | myled = !myled; |
| 4180_1 | 0:7db73d1dc65f | 37 | wait(.5); |
| 4180_1 | 0:7db73d1dc65f | 38 | } |
| 4180_1 | 0:7db73d1dc65f | 39 | } |