MP3 & Blynk-Controlled Ultrasonic Sensor System

This project combines an ultrasonic sensor, an MP3 audio module, and Blynk integration to detect motion and trigger audio responses remotely via a mobile app.

Features

• Measures distance using an ultrasonic sensor (HC-SR04 or equivalent).
• Plays audio feedback (Yes/No) via MP3 module (e.g., DFPlayer or compatible).
• Integrates with Blynk IoT platform for real-time monitoring and control.
• Sends detection status (movement or no movement) to Blynk app.
• Allows the user to trigger pre-recorded responses through Blynk buttons.

Hardware Requirements

• ESP32 board
• Ultrasonic Sensor (e.g., HC-SR04)
• MP3 Module (e.g., DFPlayer Mini or RedMP3)
• MicroSD card with audio files named 01/01.mp3 (Yes) and 01/02.mp3 (No)
• Power supply for ESP32 and MP3 module
• Breadboard and jumper wires

Pin Configuration

Component	ESP32 Pin
Ultrasonic Trigger	5
Ultrasonic Echo	18
MP3 RX	22
MP3 TX	21

How It Works

1. The ultrasonic sensor continuously measures the distance to nearby objects.
2. If an object is detected within 100 cm, it updates virtual pin V0 in the Blynk app to indicate motion.
3. The Blynk app provides two buttons:
   • V1 (Yes): Plays audio file 01/01.mp3.
   • V2 (No): Plays audio file 01/02.mp3.
4. Audio is played through the MP3 module, and playback is stopped after the file duration.

Software Requirements

• Blynk library
• RedMP3 or compatible MP3 library
• ESP32 board package in Arduino IDE
• Correct WiFi credentials and Blynk Auth Token

WiFi & Blynk Setup

Make sure to replace the following in the code:

Blynk.begin(BLYNK_AUTH_TOKEN, "YOUR_WIFI_SSID", "YOUR_WIFI_PASSWORD");