//Note, most of this code is adapted from code written by bildr. www.bildr.org

int SER_Pin = 8;   //pin 14 on the 75HC595
int RCLK_Pin = 9;  //pin 12 on the 75HC595
int SRCLK_Pin = 10; //pin 11 on the 75HC595

int map_delay = 0;

//How many of the shift registers - change this
#define number_of_74hc595s 2 

//do not touch
#define numOfRegisterPins number_of_74hc595s * 8

boolean registers[numOfRegisterPins];

void setup(){
  pinMode(SER_Pin, OUTPUT);
  pinMode(RCLK_Pin, OUTPUT);
  pinMode(SRCLK_Pin, OUTPUT);
  
  pinMode(0, INPUT);
  
 for (int thisPin = 2; thisPin < 8; thisPin++)  {
    pinMode(thisPin, OUTPUT);      
  }

  //reset all register pins
  clearRegisters();
  writeRegisters();
}               

//set all register pins to LOW
void clearRegisters(){
  for(int i = numOfRegisterPins - 1; i >=  0; i--){
     registers[i] = LOW;
  }
} 

//Set and display registers
//Only call AFTER all values are set how you would like (slow otherwise)
void writeRegisters(){

  digitalWrite(RCLK_Pin, LOW);

  for(int i = numOfRegisterPins - 1; i >=  0; i--){
    digitalWrite(SRCLK_Pin, LOW);

    int val = registers[i];

    digitalWrite(SER_Pin, val);
    digitalWrite(SRCLK_Pin, HIGH);

  }
  digitalWrite(RCLK_Pin, HIGH);

}

//set an individual pin HIGH or LOW
void setRegisterPin(int index, int value){
  registers[index] = value;
}

void loop(){

for (int thisPin = 1; thisPin < numOfRegisterPins; thisPin++) {
    setRegisterPin(thisPin, HIGH);
    writeRegisters();

    delay((map_delay = map((analogRead(0)), 0, 1023, 0, 500)));                  
    setRegisterPin(thisPin, LOW);
    writeRegisters();    
}
}

//www.esologic.com