File content as of revision 3:17c6a539bd7c:

#include "mbed.h"

// Labs 2: Example program for polling an input
// --------------------------------------------
// The program uses a thread to poll a digital input
//   - The thread monitors the position of the button
//   - When the button transitions up and down, a press event is signaled 
//   - Button bounce is guarded against
// A second thread (the default one) checks for the press event and toggles the LED

DigitalIn b1(PTD0, PullUp);
DigitalOut led(LED1);

Thread pollT ; // thread to poll
volatile int pressEvent = 0 ;  // Variabe set by the polling thread

enum buttonPos { up, down, bounce }; // Button positions
void polling() {
    buttonPos pos = up ;
    int bcounter = 0 ;
    while (true) {
        switch (pos) {
            case up :
                if (!b1.read()) {    // now down 
                    pressEvent = 1 ;  // transition occurred
                    pos = down ;
                }
                break ;
            case down : 
                if (b1 == 1) { // no longer down
                    bcounter = 3 ; // wait four cycles
                    pos = bounce ;
                }
                break ;
            case bounce :
                if (b1 == 0) { // down again - button has bounced
                    pos = down ;   // no event
                } else if (bcounter == 0) {
                    pos = up ;     // delay passed - reset to up
                } else {
                    bcounter-- ;   // continue waiting
                }
                break ;
        }
        Thread::wait(30);
    }
}

/*  ---- Main function (default thread) ----
    Note that if this thread completes, nothing else works
 */
enum states { flashing, timeToCheck }; // flsh thread states
int main() {
    int speed = 200;
    states state = flashing;
    int cycleCounter = 0;
    led = 0; // LED is on by default
    
    pollT.start(callback(polling));

    while(true) {
        Thread::wait(100);
        cycleCounter++;
        
        if (cycleCounter == 1) {
            state = timeToCheck;
        }
        
        switch (state) {
            case flashing:
                if (cycleCounter == speed / 100) {
                    led = !led;
                    cycleCounter = 0;
                }
                break;
            case timeToCheck:
                if (pressEvent) {
                    cycleCounter = 0;
                    pressEvent = 0 ; // clear the event variable
                    if (speed < 1000) {
                        speed = speed + 200;
                    } else {
                        speed = 200;
                    }
                }
                state = flashing;
                break;
        }
    }
}