// check multiple buttons and toggle LEDs

enum { Off = HIGH, On = LOW };

byte PinsLed [] = { A0, A1, 6 };
#define N_LED   sizeof(PinsLed)

byte PinsBut [] = { 7, 8 };
#define N_BUT   sizeof(PinsBut)

byte butState [N_BUT];

const unsigned long MsecPeriod = 500;
unsigned long msecLed [N_LED];
bool          active  [N_LED];

char s [90];

// -----------------------------------------------------------------------------
void
loop ()
{
    unsigned long msec = millis ();

    for (unsigned n = 0; n < N_LED; n++)  {
        if (active [n] && msec - msecLed [n] >= MsecPeriod) {
            active [n] = false;
            digitalWrite (PinsLed [n], Off);
            sprintf (s, " %d expired", n);
            Serial.println (s);
        }
    }

    for (unsigned n = 0; n < N_BUT; n++)  {
        byte but = digitalRead (PinsBut [n]);
        if (butState [n] != but)  {
            butState [n] = but;
            delay (200);             // debounce
            if (LOW == but)  {
                msecLed [n] = msec;     // only used if acitve
                active  [n] = true;
                sprintf (s, " %d active", n);
                Serial.println (s);
            }
        }

        active [2] =  (active [0] && active [1]);
        if (active [2])  {
            active [0] = active [1] = false;
            digitalWrite (PinsLed [2], On);
            sprintf (s, " %d on", 2);
            Serial.println (s);
        }
        else if (active [1])  {
            digitalWrite (PinsLed [1], On);
            sprintf (s, " %d on", 1);
            Serial.println (s);
        }
        else if (active [0])  {
            digitalWrite (PinsLed [0], On);
            sprintf (s, " %d on", 0);
            Serial.println (s);
        }
    }
}

// -----------------------------------------------------------------------------
void
setup ()
{
    Serial.begin (9600);

    for (unsigned n = 0; n < sizeof(PinsBut); n++)  {
        pinMode (PinsBut [n], INPUT_PULLUP);
        butState [n] = digitalRead (PinsBut [n]);
    }

    for (unsigned n = 0; n < sizeof(PinsLed); n++)  {
        digitalWrite (PinsLed [n], Off);
        pinMode      (PinsLed [n], OUTPUT);
    }
}