ID Mood Badge v0 - original Arduinoified code.ino

#include <avr/sleep.h>
#include <avr/interrupt.h>

const int switchPin = 3; // Define our button pin
const int redLED = 2; // Now the LED pins
const int yellowLED = 1;
const int greenLED = 0;

int LEDpin = greenLED; // start on green LED

void setup() {
    // Configure our input and output pins
    pinMode(switchPin, INPUT_PULLUP); // use the internal pull-up resistor
    pinMode(redLED, OUTPUT);
    pinMode(yellowLED, OUTPUT);
    pinMode(greenLED, OUTPUT);

    // Flash quick sequence so we know setup has started
    for (int k = 0; k < 10; k = k + 1) {
        if (k % 2 == 0) {
            digitalWrite(redLED, HIGH);
            digitalWrite(yellowLED, HIGH);
            digitalWrite(greenLED, HIGH);
        }
        else {
            digitalWrite(redLED, LOW);
            digitalWrite(yellowLED, LOW);
            digitalWrite(greenLED, LOW);
        }
        delay(250);
    }
    digitalWrite(LEDpin, HIGH); // light the selected LED!
}

void sleep() {

    GIMSK |= _BV(PCIE);                     // Enable Pin Change Interrupts
    PCMSK |= _BV(PCINT3);                   // Use PB3 as interrupt pin  
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);    // set the correct mode

    sleep_enable();                         // Sets the Sleep Enable bit in the MCUCR Register (SE BIT)
    sei();                                  // Enable interrupts
    sleep_cpu();                            // sleep
// =========================================== sleeps here
    cli();                                  // Disable interrupts
    PCMSK &= ~_BV(PCINT3);                  // Turn off PB3 as interrupt pin
    sleep_disable();                        // Clear SE bit
    sei();                                  // Enable interrupts
}

ISR(PCINT0_vect) { // Runs when the button is pushed
    if (digitalRead(switchPin) == HIGH) {
        digitalWrite(LEDpin, LOW); // turn off the current LED
        if (LEDpin < redLED) { // if we're not currently on red...
            LEDpin++; // ...we iterate the pin by one
        }
        else {
            LEDpin = greenLED; // otherwise we cycle back to green again
        } 
        digitalWrite(LEDpin, HIGH); // Light the new LED
    }
}

void loop() {
    sleep(); // call our sleep routine
}

Ton of stuff in here is wrong, interrupt code mostly. Refactored in v2