#include <TM1637Display.h>
//HC-SR04
#define echoPin  2
#define trigPin  3
#define resetPin 4

// 4-digital display pins
#define CLK 8
#define DIO 9
TM1637Display display(CLK, DIO);

float duration; //micro second
float cm;
long numDisplay = 100;
boolean trigUp = false;
boolean trigDown = false;
float counterSitUp = 0;
int buzzer = 7; // Passive buzzer pin

void setup() {

  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(resetPin, INPUT_PULLUP);
  display.setBrightness(4);
  display.clear();
  delay(500);
  display.showNumberDecEx(numDisplay, false, true, 4, 0);

}


void loop() {

  //reset by switch
  if (digitalRead(resetPin) == 0) {
    trigUp = false;
    trigDown = false;
    counterSitUp = 0;
  }
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(100);
  // receive, convert time (us) to cm
  duration = pulseIn(echoPin, HIGH);
  cm = duration * 0.034 / 2.;
  if (cm > 15 && cm <= 30) {
    trigUp = true;
  }
  else if (cm < 10) {
    trigDown = true;
  }
  else if (cm > 30) {
  }

  if (trigUp == true && trigDown == true) {
    counterSitUp = counterSitUp + 0.5;
    trigUp = false;
    delay(500);
    tone(7, 800, 40); //buzzer pin 7 frequency 800 duration 500
    trigDown = false;
  }

  display.showNumberDecEx(counterSitUp, false, true, 4, 0);
}