#include "Arduino.h"
#include "SoftwareSerial.h"
#include "DFRobotDFPlayerMini.h"

SoftwareSerial mySoftwareSerial(10, 11);
DFRobotDFPlayerMini myDFPlayer;

#define LED 6
#define TRIG 4
#define ECHO 5
#define TRIG_DIST 100 // min trigger distance
#define SOUND 7

long duration, cm;

void setup() {
  mySoftwareSerial.begin(9600);
  Serial.begin(9600);
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(SOUND, OUTPUT);
  pinMode(LED, OUTPUT);

  if (!myDFPlayer.begin(mySoftwareSerial)) {
    Serial.println(F("Unable to begin:"));
    Serial.println(F("1.Please recheck the connection!"));
    Serial.println(F("2.Please insert the SD card!"));
    while(true){
      delay(0);
    }
  }
  
  myDFPlayer.volume(20);
}

void loop() {

  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
  duration = pulseIn(ECHO, HIGH);
  cm = duration / 58;

  Serial.println(cm);

  if(cm <= TRIG_DIST) {
    myDFPlayer.play(1);

    for(int i=0; i<50; i++) {
      analogWrite(LED, i*5);
      delay(50-i);
    }

    analogWrite(LED, 255);
    delay(5000);

  } else {
    digitalWrite(LED, LOW);
  }
}