#include <Arduino.h>

// ---------- 7seg Click (74HC595) ----------
#define DATA_PIN  D3   // SDA / MOSI -> DS
#define CLOCK_PIN D4   // SCL / SCK  -> SHCP
#define LATCH_PIN D5   // LT         -> STCP

// Prototype (IMPORTANT)
void writeRegisters(uint16_t registers);

uint8_t digits[] = {
  0b01111110, // 0
  0b00001010, // 1 
  0b10110110, // 2 
  0b10011110, // 3 
  0b11001010, // 4 
  0b11011100, // 5 
  0b11111100, // 6 
  0b00001110, // 7
  0b11111110, // 8
  0b11011110  // 9 
};

void display(uint8_t value)
{
  uint8_t compteur_0;
  uint8_t compteur_1;

  compteur_1 = value / 10;   // dizaines
  compteur_0 = value % 10;   // unités

  uint16_t data = digits[compteur_0];
  data <<= 8;
  data |= digits[compteur_1];

  writeRegisters(data);
}

void setup() {
  pinMode(DATA_PIN, OUTPUT);
  pinMode(CLOCK_PIN, OUTPUT);
  pinMode(LATCH_PIN, OUTPUT);
}

uint8_t value = 0;

void loop() {
  display(value);
  delay(500);

  value++;
  if (value > 99) {
    value = 0;
  }
}

void writeRegisters(uint16_t registers)
{
  digitalWrite(LATCH_PIN, LOW);
  shiftOut(DATA_PIN, CLOCK_PIN, MSBFIRST, highByte(registers));
  shiftOut(DATA_PIN, CLOCK_PIN, MSBFIRST, lowByte(registers));
  digitalWrite(LATCH_PIN, HIGH);
}