Arduino Charlieplexing

gistfile1.cpp

static const byte charlie_pins[] = {5, 6, 7};
static const byte charlie_led[][2] = {
  { 0, 1 },
  { 1, 0 },
  { 0, 2 },
  { 2, 0 },
  { 1, 2 },
  { 2, 1 }
};

void charlie(int n_led, boolean state)
{
    byte *led = charlie_led[n_led];
    byte vcc = led[0], gnd = led[1];
    byte z = charlie_pins[(byte[]){2, 0, 1, 0}[(1 << vcc | 1 << gnd) - 3]];
    vcc = charlie_pins[vcc];
    gnd = charlie_pins[gnd];

    pinMode(vcc, OUTPUT);
    pinMode(gnd, OUTPUT);
    pinMode(z, INPUT);

    digitalWrite(gnd, LOW);
    digitalWrite(vcc, state);
}

void setup()
{
    for (int i = 0; i < 6; i++)
      charlie(i, false);
}

void loop() {
    static byte state = 0, led = 0, blinks = 0;

    if (++blinks > 10) {
       blinks = 0;
       if (++led > 5)
          led = 0;
    }

    charlie(led, state);

    state ^= 1;
    delay(100);
}