coil.ino

int latchPin = 3;
int clockPin = 4;
int dataPin = 2;

int numOfRegisters = 2;
byte registerState[2];


int pause = 2000;

void setup(void)
{
  Serial.begin(9600);
  //while( !Serial ) {} // wait for serial init

  //byte registerState = new byte[numOfRegisters];
  for (size_t i = 0; i < numOfRegisters; i++) {
    registerState[i] = 0;
  }
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);

}

void loop(void)           
{
  Serial.println("PING");
coil_write(0,2);
  delay(pause);
  Serial.println("PONG");
coil_write(0,1);
  delay(pause);
}

void coil_write(int coil_id,int state){
  int dir_0_pin;
  int dir_1_pin;
  int onoff_pin;
  int dir;
  int onoff;
 if(coil_id%2 == 0) {
  int shifter_id = coil_id/2;
    dir_0_pin = (shifter_id*8)+2;
    dir_1_pin = (shifter_id*8)+4;
    onoff_pin = (shifter_id*8)+3;
 }else if(coil_id%2 == 1){
    float shifter_id_float = (coil_id/2)-0.5;
    int shifter_id = int(shifter_id_float);
    dir_0_pin = (shifter_id*8)+5;
    dir_1_pin = (shifter_id*8)+7;
    onoff_pin = (shifter_id*8)+6;
 }
 if(state == 0) {
  onoff = 0;
 }
 else if(state == 1){
  onoff = 1;
  dir = 0;
 }
 else if(state == 2){
  onoff = 1;
  dir = 1;
 }
  regWrite(onoff_pin,onoff); 
  regWrite(dir_0_pin, dir);
  regWrite(dir_1_pin, !dir);
}

void regWrite(int p, bool state) {
  int reg = p / 8;
  int actualPin = p - (8 * reg);
  digitalWrite(latchPin, LOW);
  for (int i = 0; i < numOfRegisters; i++) {
    //byte states = registerState[i];
    if (i == reg) {
      bitWrite(registerState[i], actualPin, state);
    }
    shiftOut(dataPin, clockPin, MSBFIRST, registerState[i]);
  }
  digitalWrite(latchPin, HIGH);
}