Section outline

  • Getting to Know Bluetooth Modules (HC-05, HC-06)

    Bluetooth modules like HC-05 and HC-06 allow your Arduino-based robots to wirelessly receive commands from a mobile device. Understanding how these modules work is key to building wirelessly controlled robots.

    • 🔷 What is the HC-05/HC-06 Module?

      • Both are popular Bluetooth modules used in hobby electronics.
      • HC-05 can work as both Master and Slave.
      • HC-06 works only in Slave mode (for receiving commands).

    • 📦 Pin Description

      Pin Description
      VCC Connect to 5V (power)
      GND Ground
      TXD Transmit Data (connects to Arduino RX)
      RXD Receive Data (connects to Arduino TX via voltage divider)
      STATE / EN / KEY Used in advanced configuration (not required for basic use)

      🔌 Basic Wiring with Arduino

      • HC-05 VCC → Arduino 5V
      • HC-05 GND → Arduino GND
      • HC-05 TXD → Arduino RX (pin 0)
      • HC-05 RXD → Arduino TX (pin 1) via 1K–2K voltage divider

      ⚠️ Important Note:

      The HC-05 RXD pin is not 5V tolerant, so it's recommended to use a voltage divider when connecting to Arduino TX to avoid damaging the module.

      📶 Pairing the Module

      • Turn on Bluetooth on your phone.
      • Scan for devices — look for “HC-05” or “HC-06”.
      • Default pairing code is usually 1234 or 0000.
      • Once paired, your phone can communicate with the robot using apps like MIT App Inventor or Bluetooth Terminal.

      ✅ What You’ve Learned

      • The difference between HC-05 and HC-06
      • Pin functions and connection to Arduino
      • How to wire and pair your Bluetooth module