//Задание 1: Без использования библиотек вывести на 4х разрядный 7-сегментный дисплей
// счетчик. Если в COM порт послать число, то счетчик должен начать отсчет от
// этого числа, и до 0. 

int A = 4;
int B = 8;
int C = 9;
int D = 10;
int E = 11;
int F = 12;
int G = 7;


int counter = 100;
int my_counter = 0;

unsigned long previousMillis;
const unsigned long interval = 1000UL;

void setup() {
  
  Serial.begin(115200);
  Serial.println("Введите число: ");
  //while(!Serial.available()){}
  //delay(5000);
  // String teststr = Serial.readString();  //read until timeout
  // teststr.trim();   
  // my_counter = teststr.toInt();
  //my_counter = Serial.parseInt();
  //Serial.println(my_counter);

  // // Initialize the pins of the 4 digits for the multiplexed signals.
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT);
  pinMode(C, OUTPUT);
  pinMode(D, OUTPUT);
  pinMode(E, OUTPUT);
  pinMode(F, OUTPUT);
  pinMode(G, OUTPUT);


}



void switch_segment(int Digit)
{
  switch(Digit)
  {
    case 0:
        digitalWrite(A, LOW);
        digitalWrite(B, LOW);
        digitalWrite(C, LOW);
        digitalWrite(D, LOW);
        digitalWrite(E, LOW);
        digitalWrite(F, LOW);
        break;
    case 1:
        digitalWrite(B, LOW);
        digitalWrite(C, LOW);
        break;
    case 2:
        digitalWrite(A, LOW);
        digitalWrite(B, LOW);
        digitalWrite(D, LOW);
        digitalWrite(E, LOW);
        digitalWrite(G, LOW);
        break;
    case 3:
        digitalWrite(A, LOW);
        digitalWrite(B, LOW);
        digitalWrite(C, LOW);
        digitalWrite(D, LOW);
        digitalWrite(G, LOW);
        break;
    case 4:
        digitalWrite(B, LOW);
        digitalWrite(C, LOW);
        digitalWrite(F, LOW);
        digitalWrite(G, LOW);
        break;
    case 5:
        digitalWrite(A, LOW);
        digitalWrite(C, LOW);
        digitalWrite(D, LOW);
        digitalWrite(F, LOW);
        digitalWrite(G, LOW);
        break;
    case 6:
        digitalWrite(A, LOW);
        digitalWrite(C, LOW);
        digitalWrite(D, LOW);
        digitalWrite(E, LOW);
        digitalWrite(F, LOW);
        digitalWrite(G, LOW);
        break;
    case 7:
        digitalWrite(A, LOW);
        digitalWrite(B, LOW);
        digitalWrite(C, LOW);
        break;
    case 8:
        digitalWrite(A, LOW);
        digitalWrite(B, LOW);
        digitalWrite(C, LOW);
        digitalWrite(D, LOW);
        digitalWrite(E, LOW);
        digitalWrite(F, LOW);
        digitalWrite(G, LOW);
        break;
    case 9:
        digitalWrite(A, LOW);
        digitalWrite(B, LOW);
        digitalWrite(C, LOW);
        digitalWrite(D, LOW);
        digitalWrite(F, LOW);
        digitalWrite(G, LOW);
        break;
  }


}

void clear_segment(){
  digitalWrite(A, HIGH);
  digitalWrite(B, HIGH);
  digitalWrite(C, HIGH);
  digitalWrite(D, HIGH);
  digitalWrite(E, HIGH);
  digitalWrite(F, HIGH);
  digitalWrite(G, HIGH);

}

void ShowNumber_on_Display(int l_igit, int th_digit, int sec_digit, int f_digit)
{
  clear_segment();
  digitalWrite(2, HIGH);
  switch_segment(l_igit);
  digitalWrite(2, LOW);
  delay(20);
  clear_segment();
  
  digitalWrite(6, HIGH);
  switch_segment(th_digit);
  digitalWrite(6, LOW);
  delay(20);
  clear_segment();
  
  digitalWrite(5, HIGH);
  switch_segment(sec_digit);
  digitalWrite(5, LOW);
  delay(20);
  clear_segment();

  digitalWrite(3, HIGH);
  switch_segment(f_digit);
  digitalWrite(3, LOW);
  delay(20);
  clear_segment();
}



void loop() {
  if(Serial.available()> 0)
  {
    my_counter = Serial.parseInt();
    Serial.read();
    Serial.println("Введенное число: " + String(my_counter));
  }
  
  // установка отрицательных значений в 0 или больших 9999
  if (my_counter < 0 or my_counter > 9999) my_counter = 0;
  
  unsigned long currentMillis = millis();

  int lastdigit = my_counter % 10; 
  int third_digit = (my_counter / 10) % 10;
  int second_digit = (my_counter / 100) % 10;
  int first_digit = my_counter / 1000;
  
  ShowNumber_on_Display(lastdigit, third_digit, second_digit, first_digit);
  
  if(currentMillis - previousMillis >= interval)
  {
    previousMillis = currentMillis;
    my_counter--;
  }

}