How to Use XY-MD02: Examples, Pinouts, and Specs

The XY-MD02 is a wireless Bluetooth module designed for seamless communication between devices. It supports serial communication (UART) and operates using the Bluetooth 4.0 protocol, making it ideal for low-power and high-speed data transmission. This module is widely used in IoT applications, enabling microcontrollers to connect to smartphones, tablets, or other Bluetooth-enabled devices. Its compact size and ease of integration make it a popular choice for hobbyists and professionals alike.

• Wireless data transmission between microcontrollers and smartphones
• IoT devices and smart home automation
• Remote control systems
• Wireless sensor networks
• Robotics and industrial automation

The XY-MD02 module is designed to provide reliable and efficient Bluetooth communication. Below are its key technical specifications:

The XY-MD02 module has 6 pins, as described in the table below:

The XY-MD02 module is straightforward to use and can be easily integrated into a circuit. Below are the steps and best practices for using the module:

1. Power Supply: Connect the VCC pin to a 3.3V or 5V power source and the GND pin to the ground.
2. Serial Communication:
   • Connect the TXD pin of the module to the RX pin of the microcontroller.
   • Connect the RXD pin of the module to the TX pin of the microcontroller.
3. Enable Pin: Leave the EN pin unconnected for normal operation. Pull it high to enter AT command mode.
4. Status Pin: Optionally, connect the STATE pin to an LED or microcontroller input to monitor the connection status.

Below is an example of how to use the XY-MD02 module with an Arduino UNO to send and receive data via Bluetooth.

• Connect VCC to the 5V pin on the Arduino.
• Connect GND to the GND pin on the Arduino.
• Connect TXD to pin 10 on the Arduino (software serial RX).
• Connect RXD to pin 11 on the Arduino (software serial TX).

#include <SoftwareSerial.h>

// Define software serial pins for the XY-MD02 module
SoftwareSerial bluetooth(10, 11); // RX, TX

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);
  // Initialize Bluetooth module communication
  bluetooth.begin(9600); // Default baud rate for XY-MD02
  Serial.println("Bluetooth module ready. Waiting for connection...");
}

void loop() {
  // Check if data is available from the Bluetooth module
  if (bluetooth.available()) {
    char received = bluetooth.read(); // Read the incoming data
    Serial.print("Received: ");
    Serial.println(received); // Print the received data to the serial monitor
  }

  // Check if data is available from the serial monitor
  if (Serial.available()) {
    char toSend = Serial.read(); // Read the data from the serial monitor
    bluetooth.write(toSend); // Send the data to the Bluetooth module
    Serial.print("Sent: ");
    Serial.println(toSend); // Print the sent data to the serial monitor
  }
}

• Voltage Levels: Ensure the module operates within its voltage range (3.3V to 6V). If using a 3.3V microcontroller, use a level shifter for the TXD and RXD pins.
• Baud Rate: The default baud rate is 9600 bps. Use AT commands to change it if needed.
• Command Mode: Pull the EN pin high to enter AT command mode for configuration. Use a serial terminal to send AT commands.
• Antenna Placement: Avoid placing the module near metal objects or other RF sources to ensure optimal signal strength.

1. Module Not Responding

   • Cause: Incorrect wiring or power supply.
   • Solution: Double-check the connections and ensure the module is powered correctly.

2. No Data Transmission

   • Cause: Baud rate mismatch between the module and microcontroller.
   • Solution: Verify the baud rate settings and adjust if necessary using AT commands.

3. Unstable Connection

   • Cause: Interference or poor signal strength.
   • Solution: Ensure the module is within the specified range and away from interference sources.

4. Cannot Enter AT Command Mode

   • Cause: EN pin not pulled high.
   • Solution: Pull the EN pin high and reset the module to enter command mode.

Q1: Can the XY-MD02 module be used with a 3.3V microcontroller?
A1: Yes, the module supports 3.3V operation. However, ensure proper voltage level shifting for the TXD and RXD pins if needed.

Q2: How do I reset the module to factory settings?
A2: Enter AT command mode and send the AT+RESET command to reset the module.

Q3: What is the maximum data rate supported by the module?
A3: The module supports a maximum baud rate of 115200 bps, configurable via AT commands.

Q4: Can I use the module for audio transmission?
A4: No, the XY-MD02 is designed for data transmission only and does not support audio profiles.

By following this documentation, you can effectively integrate and use the XY-MD02 Bluetooth module in your projects.