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Product Description
A highly versatile, easy-to-configure Bluetooth Classic (2.1 + EDR) serial transceiver module designed for robust wireless communication, remote data logging, and smart mobile apps in Arduino and ESP32 projects. Unlike “slave-only” modules, the HC-05 can be configured dynamically as either a Master or a Slave device. This allows it to not only receive data from Android phones or PCs, but also proactively initiate wireless connections with other Bluetooth devices, such as pairing two microcontroller platforms together. Running on standard UART serial communication with a comprehensive AT command set, this module simplifies building wireless joysticks, remote-controlled robots, and off-grid wireless telemetry bridges.
Pinout / Layout Connections
The module breaks out its serial pipeline and state parameters via a convenient 6-pin male header block:
EN (Enable / Key) Pin: Mode configuration pin. Pull this HIGH before powering up the module to force it into AT Command Mode (for configuring baud rates, passwords, or Master/Slave roles).
VCC Pin: Power supply input. Accepts DC +3.6V to +6V (equipped with an onboard low-dropout voltage regulator).
GND Pin: Common system ground (0V) reference.
TXD Pin: Asynchronous Serial Data Output. Transmits received wireless data packets to the host microcontroller’s RX line.
RXD Pin: Asynchronous Serial Data Input. Receives data from the host microcontroller. Requires a 5V-to-3.3V resistor voltage divider when interfacing with a 5V Arduino board to protect the chip’s native 3.3V logic level.
STATE Pin: Connection status output. Can be monitored to verify whether the Bluetooth link is active or searching.
