Charlieplexing with Arduino

//--------------------------------------------
//
//             Charlieplexing Demo
//
//              Learnelectronics
//               Aug, 23, 2019
//
//      www.youtube.com/c/learnelectronics
//        email: [email protected]
//
//---------------------------------------------



#define A 8                     // We call pin #8 A
#define B 9                     // "   "   "   #9 B
#define C 10                    // "   "   "  #10 C
#define D 11                    // "   "   "  #11 D

#define PIN_CONFIG 0            // Setup our Boolean config for the 4 pins
#define PIN_STATE 1             // Setup our Boolean state for the 4 pins

#define LED_Num 12              // How many LEDs are we using


// Now we have to create a matrix for the pins so we know which of the 3 states they are in

int matrix[LED_Num][2][4] = {
  //           PIN_CONFIG                  PIN_STATE
  //    A       B       C      D         A     B    C    D
  { { OUTPUT, OUTPUT, INPUT, INPUT }, { HIGH, LOW, LOW, LOW } },
  { { OUTPUT, OUTPUT, INPUT, INPUT }, { LOW, HIGH, LOW, LOW } },
  { { INPUT, OUTPUT, OUTPUT, INPUT }, { LOW, HIGH, LOW, LOW } },
  { { INPUT, OUTPUT, OUTPUT, INPUT }, { LOW, LOW, HIGH, LOW } },
  { { OUTPUT, INPUT, OUTPUT, INPUT }, { HIGH, LOW, LOW, LOW } },
  { { OUTPUT, INPUT, OUTPUT, INPUT }, { LOW, LOW, HIGH, LOW } },
  { { OUTPUT, INPUT, INPUT, OUTPUT }, { HIGH, LOW, LOW, LOW } },
  { { OUTPUT, INPUT, INPUT, OUTPUT }, { LOW, LOW, LOW, HIGH } },
  { { INPUT, OUTPUT, INPUT, OUTPUT }, { LOW, HIGH, LOW, LOW } },
  { { INPUT, OUTPUT, INPUT, OUTPUT }, { LOW, LOW, LOW, HIGH } },
  { { INPUT, INPUT, OUTPUT, OUTPUT }, { LOW, LOW, HIGH, LOW } },
  { { INPUT, INPUT, OUTPUT, OUTPUT }, { LOW, LOW, LOW, HIGH } }
};


//Here we turn the LED on by changing the pin state and mode
void lightOn( int led ) {
  pinMode( A, matrix[led][PIN_CONFIG][0] );
  pinMode( B, matrix[led][PIN_CONFIG][1] );
  pinMode( C, matrix[led][PIN_CONFIG][2] );
  pinMode( D, matrix[led][PIN_CONFIG][3] );
  digitalWrite( A, matrix[led][PIN_STATE][0] );
  digitalWrite( B, matrix[led][PIN_STATE][1] );
  digitalWrite( C, matrix[led][PIN_STATE][2] );
  digitalWrite( D, matrix[led][PIN_STATE][3] );
}

void setup() {}


//here we just incrementally change the number of the LED to beturned on.
void loop() {
  for( int l = 0; l < LED_Num; l++ ) {
    lightOn( l );
    delay( 5000 / LED_Num );
  }
}