How to make sound alert with ultrasonic sensor

In this post you will know  how  to build a sound alarm with ultrasonic sensor. You can use this system in many places. For example: Sound guide, (to guide someone to certain direction when he/she comes front of the sensor) to make yourself aware of something or someone and many more.

The sketch

#include <SoftwareSerial.h> #define ARDUINO_RX 5 //should connect to TX of the Serial MP3 Player module #define ARDUINO_TX 6 //connect to RX of the module SoftwareSerial mySerial(ARDUINO_RX, ARDUINO_TX); static int8_t Send_buf[8] = {0} ; #define CMD_SEL_DEV 0X09 #define DEV_TF 0X02 #define CMD_PLAY_W_VOL 0X22 int trigPin1 = 9; int echoPin1 = 8; void setup() {   pinMode(trigPin1, OUTPUT);   pinMode(echoPin1, INPUT);       mySerial.begin(9600);         Serial.begin(9600);       delay(500);//Wait chip initialization is complete         sendCommand(CMD_SEL_DEV, DEV_TF);//select the TF card        delay(200);//wait for 200ms } void loop() { delay(280); Serial.println("\n");  int duration1, distance1;   digitalWrite (trigPin1, HIGH);   delayMicroseconds (10);   digitalWrite (trigPin1, LOW);   duration1 = pulseIn (echoPin1, HIGH);   distance1 = (duration1/2) / 29.1;       Serial.print("1st Sensor: ");       Serial.print(distance1);       Serial.print("cm  ");   if (distance1 < 40) {  // Change the number for long or short distances.  sendCommand(CMD_PLAY_W_VOL, 0X1E001);//play the second song with volume 30 class    delay(300);   } else { // nothing   }   } void sendCommand(int8_t command, int16_t dat) {   delay(20);   Send_buf[0] = 0x7e; //starting byte   Send_buf[1] = 0xff; //version   Send_buf[2] = 0x06; //the number of bytes of the command without starting byte and ending byte   Send_buf[3] = command; //   Send_buf[4] = 0x00;//0x00 = no feedback, 0x01 = feedback   Send_buf[5] = (int8_t)(dat >> 8);//datah   Send_buf[6] = (int8_t)(dat); //datal   Send_buf[7] = 0xef; //ending byte   for(uint8_t i=0; i<8; i++)//   {     mySerial.write(Send_buf[i]) ;   } }

What do you need:
1x Arduino board
1x Ultrasonic Sensor
1x Serial MP3 player
1x Loud speaker
1x SD card with a sound track in (Make sure you name the sound track 001)
And Few jumper wires.

Note: If you need extra help to set the sound please see this post.

Watch the video to see the sketch in action