Overview: The HC-05 Bluetooth Serial Module is a compact, low-cost wireless communication board designed for short-range data transfer between devices using Bluetooth 2.0+EDR protocol. Featuring the CSR BC417 Bluetooth IC, this module acts as a UART-to-Bluetooth bridge, enabling serial communication for microcontrollers like Arduino, Raspberry Pi, or embedded systems. It’s ideal for DIY projects requiring wireless control, such as remote sensors, robotics, home automation, or PC-to-device links. The blue PCB includes an onboard antenna for reliable connectivity up to 10 meters in open space, with master/slave mode support for versatile pairing.
Key Specifications:
Parameter
Value/Detail
Bluetooth Version
2.0 + EDR (Enhanced Data Rate)
IC Chip
CSR BC417 (Bluetooth Controller)
Operating Voltage
3.6V – 6V DC (5V typical; logic 3.3V)
Operating Current
30mA (typical); <1mA sleep mode
Data Rate
Up to 1Mbps (2.1Mbps EDR peak)
Range
Up to 10m (class 2, open air)
Frequency
2.4GHz ISM band
UART Baud Rate
9600 – 1382400 bps (default 38400)
Modes
Master/Slave (AT command configurable)
Dimensions
Approx. 43mm x 23mm x 10mm
Weight
~10g
Operating Temperature
-20°C to +70°C
Connections:
VCC (Pin 1): Power supply (3.6V-6V; connect to 5V on Arduino).
GND (Pin 2): Ground/common.
TXD (Pin 3): Module transmit (connect to RX on microcontroller).
RXD (Pin 4): Module receive (connect to TX on microcontroller).
STATE (Pin 5): Status indicator (HIGH when paired).
EN/KEY (Pin 34): Mode select (pull HIGH for AT command mode).
LED: Blinks for connection status (fast = pairing, slow = connected).
Supports direct pin-header soldering for breadboard use.
Features and Benefits:
Transparent Serial Bridge: Converts UART data to Bluetooth packets seamlessly—no custom code needed for basic serial passthrough.
AT Command Interface: Enter command mode (via KEY pin) to configure baud rate, name, PIN (default 1234/0000), or role (master/slave).
Pairing Simplicity: Auto-reconnects to last paired device; supports up to 7 slaves in master mode.
Low Power Design: Sleep mode reduces consumption for battery-powered applications; onboard voltage regulator for stable operation.
Robust Connectivity: Error-corrected data transmission with RSSI signal strength monitoring via AT commands.
Compact and Integrated: Blue PCB with crystal oscillator and SMD components for reliable, interference-resistant performance.
Applications:
Wireless sensor networks and IoT devices.
Bluetooth-enabled robotics and remote controls.
Serial debugging over air (e.g., Arduino to PC via Bluetooth terminal apps).
Home automation hubs for lights, motors, or appliances.
GPS or GSM module wireless extensions.
Note: Ensure 3.3V logic compatibility (use level shifter if connecting to 5V TTL). Default PIN is 1234; change for security. Test pairing in a low-interference environment.
