Wireless Serial Bluetooth Module for Arduino/RPi

The HC-Series Bluetooth Modules are compact, low-power, cost-effective wireless communication devices designed for easy serial communication between microcontrollers and Bluetooth-enabled devices. These modules offer UART (Universal Asynchronous Receiver/Transmitter) interface with support for both 3.3V TTL and RS232 logic levels, making them ideal for wireless communication with Arduino, Raspberry Pi, STM32, AVR, and other embedded systems.

Whether you need master-slave Bluetooth Classic communication, low-energy BLE support, or transparent serial data transmission, the HC-Series has multiple variants to meet diverse wireless communication needs.

Key Features:

Bluetooth Standard: Bluetooth V2.0+EDR (HC-05/HC-06), Bluetooth 4.0/4.2 (HM-10), BLE 5.0 (HM-18)
Interface: UART (TX/RX), supports AT commands for configuration
Baud Rate: Default 9600 bps (configurable via AT commands: 1200 ~ 1382400 bps)
Operating Voltage: 3.3V logic level (some variants have onboard regulator to support 5V input)
Communication Range: 5–30 meters (line of sight)
Antenna: PCB onboard antenna
Modes: Master / Slave (configurable on certain variants)
Compatibility: Arduino, STM32, PIC, AVR, ESP32, Raspberry Pi, etc.
Compact size for breadboard and prototyping use

Common Variants:

1. HC-05

Bluetooth Version: V2.0+EDR (Bluetooth Classic)
Mode: Configurable as Master or Slave
AT Command Mode: Supported (via KEY/EN pin)
Applications: Full-duplex wireless communication, Arduino to PC/Mobile, robot control
Range: ~10 meters

2. HC-06

Bluetooth Version: V2.0+EDR
Mode: Slave only
AT Command Mode: Supported (simplified)
Applications: Simple wireless UART bridge
Note: Easier to use than HC-05 for slave-only communication

3. HC-05 with Backboard

Includes onboard voltage regulator (supports 3.6V–6V supply)
Suitable for Arduino Uno, Nano (5V logic)
Easy soldering with pin headers

4. HC-06 with Backboard

Same as HC-06, with onboard 3.3V regulator
Directly pluggable into Arduino 5V boards

5. HM-10

Bluetooth Version: BLE 4.0
Mode: Slave and Master (configurable)
Low Power: Ideal for battery-powered IoT applications
iOS and Android Compatible (BLE support)
AT Commands: Fully supported
Applications: BLE remote control, smart devices, wearable communication

6. HM-18 / HM-19

Bluetooth Version: BLE 5.0
Upgraded version of HM-10 with extended range, faster data rate
Compatible with latest smartphones and BLE 5.0 features

Typical Applications:

Wireless programming/debugging of microcontrollers
Remote sensor monitoring
Wireless robot control
Home automation systems
Serial communication between devices without physical cables
Wireless data logger and terminal applications

Pinout (Standard 6-Pin Module):

Pin	Function
EN	Enable/Key pin (for AT mode)
VCC	Power supply (3.6V–6V with regulator)
GND	Ground
TXD	UART Transmit
RXD	UART Receive
STATE	Connection status (high when paired)

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