#include <Arduino.h>

// Define the connections pins
#define CLK 18 // CLK pin
#define DIO 19 // DIO pin

void startTransmission();
void endTransmission();
void writeByte(uint8_t data);
void displayNumber(int num);
void displayCountdown(int minutes, int seconds);
void setBrightness(uint8_t brightness);

const uint8_t digitToSegment[] = {
  0b00111111,  // 0
  0b00000110,  // 1
  0b01011011,  // 2
  0b01001111,  // 3
  0b01100110,  // 4
  0b01101101,  // 5
  0b01111101,  // 6
  0b00000111,  // 7
  0b01111111,  // 8
  0b01101111   // 9
};

void setup() {
  pinMode(CLK, OUTPUT);
  pinMode(DIO, OUTPUT);
  setBrightness(0x0f); // Set brightness to maximum
}

void loop() {
  int countdown = 60; // 60 seconds countdown

  while (countdown >= 0) {
    int seconds = countdown % 60;
    int minutes = (countdown / 60) % 60;

    // Display the countdown in mm:ss format
    displayCountdown(minutes, seconds);

    delay(500); // Wait for 1 second
    countdown--; // Decrease the countdown by 1
  }

  // After the countdown is over, display "0000"
  displayNumber(0);
  
  // Optional: Reset the countdown or perform another action
  // Uncomment the next line to loop the countdown indefinitely
  // countdown = 60; 
}

void startTransmission() {
  digitalWrite(CLK, LOW);
  digitalWrite(DIO, LOW);
}

void endTransmission() {
  digitalWrite(CLK, LOW);
  digitalWrite(DIO, LOW);
  digitalWrite(CLK, HIGH);
  digitalWrite(DIO, HIGH);
}

void writeByte(uint8_t data) {
  for (int i = 0; i < 8; i++) {
    digitalWrite(CLK, LOW);
    digitalWrite(DIO, (data & 0x01) ? HIGH : LOW);
    data >>= 1;
    digitalWrite(CLK, HIGH);
  }

  // Acknowledge bit
  digitalWrite(CLK, LOW);
  pinMode(DIO, INPUT);
  digitalWrite(CLK, HIGH);
  pinMode(DIO, OUTPUT);
}

void displayNumber(int num) {
  startTransmission();
  writeByte(0x40); // Command: Set data
  endTransmission();

  startTransmission();
  writeByte(0xC0); // Command: Set address

  for (int i = 0; i < 4; i++) {
    int digit = (num / (int)pow(10, 3 - i)) % 10;
    writeByte(digitToSegment[digit]);
  }

  endTransmission();
}

void displayCountdown(int minutes, int seconds) {
  startTransmission();
  writeByte(0x40); // Command: Set data
  endTransmission();

  startTransmission();
  writeByte(0xC0); // Command: Set address

  writeByte(digitToSegment[minutes / 10]);
  writeByte(digitToSegment[minutes % 10] | 0b10000000); // Add colon
  writeByte(digitToSegment[seconds / 10]);
  writeByte(digitToSegment[seconds % 10]);

  endTransmission();
}

void setBrightness(uint8_t brightness) {
  startTransmission();
  writeByte(0x88 | (brightness & 0x07)); // Command: Display control, set brightness level
  endTransmission();
}