//Constants
#define number_of_74hc595s 2 
#define numOfRegisterPins number_of_74hc595s * 8
#define SER_Pin 25
#define RCLK_Pin 33
#define SRCLK_Pin 32
//Variables
boolean registers [numOfRegisterPins];
void setup(){
//Init Serial USB
Serial.begin(115200);
Serial.println(F("Initialize System"));
//Init register
pinMode(SER_Pin, OUTPUT);
pinMode(RCLK_Pin, OUTPUT);
pinMode(SRCLK_Pin, OUTPUT);
clearRegisters();
setRegisterPin(3, HIGH);
delay(500);
writeRegisters();
delay(500);
}
void loop(){
writeGrpRelay();
}
void clearRegisters(){/* function clearRegisters */
//// Clear registers variables 
for(int i = numOfRegisterPins-1; i >=  0; i--){
 registers[i] = HIGH;//LOW;
}}
void writeRegisters(){/* function writeRegisters */
//// Write register after being set 
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);
}
void setRegisterPin(int index,int value){/* function setRegisterPin */
////Set register variable to HIGH or LOW
registers[index] = value;
}
void writeGrpRelay(){/* function writeGrpRelay */
for(int i = numOfRegisterPins-1; i >=  0; i--){
  Serial.print(F("Relay "));Serial.print(i);Serial.println(F(" HIGH"));
  setRegisterPin(i, LOW);
  writeRegisters();
  delay(200);
  Serial.print(F("Relay "));Serial.print(i);Serial.println(F(" LOW"));
  setRegisterPin(i, HIGH);
  writeRegisters();
 delay(500);
     
}
}