The HC-06 Bluetooth Module is a simple, low-cost, and widely used module for wireless serial communication. Unlike the HC-05, the HC-06 only works in Slave mode, meaning it can receive connections from a master device (like a smartphone, laptop, or HC-05 module), but it cannot initiate connections itself. 🔹 Key Features Bluetooth version: 2.0 + EDR (Enhanced Data Rate). Operating Voltage: 3.3V – 6V (internally regulated to 3.3V, safe to power with 5V). Current consumption: ~30 mA during data transmission. Communication: UART (TX, RX). Default Baud Rate: 9600 bps. Range: ~10 meters (Class 2). Default Name: "HC-06". Default Password: 1234 or 0000. Modes: Slave only (cannot act as Master). 🔹 Pin Configuration VCC → Power supply (3.6V – 6V, typically 5V). GND → Ground. TXD → Transmit data pin (connects to RX of Arduino). RXD → Receive data pin (connects to TX of Arduino, but needs 3.3V logic). (Some versions have a STATE pin for connection status, but it’s optional.) 🔹 How It Works When powered, the HC-06 waits to be discovered by another Bluetooth device. A smartphone, PC, or another master module can pair with it. Once paired, it works as a wireless serial link, just like a wired UART connection. Whatever data is sent from the Arduino via TX will be received on the paired device, and vice versa. 🔹 Applications Wireless communication with microcontrollers (Arduino, ESP32, PIC, STM32). Bluetooth-controlled robots and cars. Wireless data logging from sensors to a smartphone/PC. Home automation (controlling lights, fans, or appliances). Replacing USB/Serial cables with a wireless link. 🔹 Difference from HC-05 Feature HC-05 HC-06 Modes Master & Slave Slave only AT Commands Full support Limited support Flexibility More configurable Easier to use