File content as of revision 0:2d148f94a249:

// Quick example on buttons
// By Fernando R.

#include "mbed.h"
#include <iostream>

#define DEBOUNCE_MS 25

DigitalIn button(PTE1);
DigitalOut ledRed(LED_RED);
DigitalOut ledGreen(LED_GREEN);
DigitalOut ledBlue(LED_BLUE);

enum State {
    VERDE,
    AMARILLO,
    ROJO,
};


State nextState(State currentState);
void executeState(State state);

int main() {
    State currentState;
    while (1) {
        if (button) {
            currentState = nextState(currentState);
        }
        executeState(currentState);
    }
}

int main_alternative_for_only_once_on_press() {
    State currentState;
    int buttonThisCycle = 0;
    int buttonPreviousCycle = 0;

    while (1) {
        buttonThisCycle = button;
        if (buttonThisCycle && !buttonPreviousCycle) {
            currentState = nextState(currentState);
        }
        executeState(currentState);
        buttonPreviousCycle = buttonThisCycle;
    }
}

int main_alternative_for_only_once_on_press_with_debounce() {
    State currentState;
    int buttonThisCycle = 0;
    int buttonPreviousCycle = 0;
    Timer t;
    unsigned int timeLastPress = 0;
    t.start();

    while (1) {
        buttonThisCycle = button;
        if (buttonThisCycle && !buttonPreviousCycle) {
            int timeSinceLastPress = t.read_ms() - timeLastPress;
            if (timeSinceLastPress > DEBOUNCE_MS) {
                timeLastPress = t.read_ms();
                currentState = nextState(currentState);
            }
        }
        executeState(currentState);
        buttonPreviousCycle = buttonThisCycle;
    }
}

State nextState(State currentState) {
    switch (currentState) {
    case VERDE:
        return AMARILLO;
        break;
    case AMARILLO:
        return ROJO;
        break;
    case ROJO:
        return VERDE;
        break;
    default:
        std::cerr << "Invalid State";
    }
}

void executeState(State state) {
    switch (state) {
    case VERDE:
        ledRed = 1;
        ledGreen = 0;
        ledBlue = 1;
        break;
    case AMARILLO:
        ledRed = 0;
        ledGreen = 0;
        ledBlue = 1;
        break;
    case ROJO:
        ledRed = 0;
        ledGreen = 1;
        ledBlue = 1;
        break;
    default:
        std::cerr << "Invalid State";
    }
}