// https://forum.arduino.cc/t/max7219cng-or-74hc595-to-control-multiple-10-segment-led-bargraph/1264933

#define dataPin  2 // DS
#define clockPin 3 // SHCP
#define latchPin 4 // STCP

#define regPins 50

int pattern = 0b10101010;
bool registers[regPins];
bool state = false;

void setup() {
  randomSeed(analogRead(A0));
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
  clearRegisters();
  writeRegisters();
}

void loop() { // un-comment the selected function
  // toggle();
  // randomize();
  // patterns();
  sequential();
  // stacks();
}

//**************************************************
// display functions
//**************************************************

void patterns() {
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, pattern);
  digitalWrite(latchPin, HIGH);
  delay(500);
  pattern = ~pattern; // Invert the pattern
}

void toggle() {
  for (int i = 0; i < regPins; i++) {
    if (!(i % 2)) {
      setRegisterPin(i, state);
    } else {
      setRegisterPin(i, !state);
    }
    writeRegisters();
  }
  state = !state;
  delay(500);
}

void randomize() {
  int i = random(regPins);
  setRegisterPin(i, HIGH);
  writeRegisters();
  delay(100);
  setRegisterPin(i, LOW);
  writeRegisters();
  delay(200);
}

void sequential() {
  for (int i = 0; i < regPins - 1; i++) {
    // setRegisterPin(regPins, HIGH);
    setRegisterPin(regPins - i, HIGH);
    writeRegisters();
    // setRegisterPin(regPins, LOW);
    setRegisterPin(regPins - i, LOW);
    writeRegisters();
    delay(25);
  }
}

void stacks() {
  int j = random(5);
  for (int i = 0; i < 10; i++) {
    setRegisterPin(regPins - (j * 10 + i + 1), HIGH);
    writeRegisters();
    delay(25);
  }
  clearRegisters();
  delay(50);
}

//**************************************************
// utility functions
//**************************************************

void clearRegisters() {
  for (int i = 0; i < regPins; i++) {
    registers[i] = LOW;
  }
}

void setRegisterPin(int index, int value) { // set individual pins
  registers[index] = value;
}

void writeRegisters() {
  digitalWrite(latchPin, LOW);
  for (int i = 0; i < regPins; i++) {
    digitalWrite(clockPin, LOW);
    digitalWrite(dataPin, registers[i]);
    digitalWrite(clockPin, HIGH);
  }
  digitalWrite(latchPin, HIGH);
}