Bluetooth Module HC05 Master Slave Support

Description of Bluetooth Module HC05 Master Slave Support The HC-05 Bluetooth Module is a high-performance Bluetooth-to-Serial Bridge designed for seamless wireless communication between microcontrollers, smartphones, and PCs. Functioning as a Class 2 transceiver, it provides a reliable "transparent" serial link with a range of approximately 10 meters, effectively replacing traditional wired asynchronous interfaces. This versatile module supports both master and slave configurations on the 2.4GHz ISM band, featuring PIO control and an integrated antenna for stable data transmission without the need to manage complex Bluetooth protocols or stacks. Optimized for home automation, robotics, and embedded systems, the HC-05 allows you to pipe serial data wirelessly in a compact, lightweight 5g package. Measuring just 16.5mm x 43mm x 7mm, its edge-connector design ensures easy integration into space-constrained projects. Whether you are building remote-controlled robots or wireless sensor networks, the HC-05 offers a professional-grade, high-speed solution for bidirectional wireless connectivity.. Specification Parameter Value Model Master-slave integrated Bluetooth module Type Power Module Power HC-05 Frequency 2.4GHz ISM Band Weight 5gm Product Size 16.5mm x 43mm x 7mm Modes of Operation The HC-05 module utilizes two distinct communication modes via its serial interface to distinguish between system commands and wireless communication. In AT Mode, you can fully customize the module's internal settings, including its name, baud rate, and security PIN code. In Data Mode, the HC-05 functions as a transparent gateway, automatically handling Bluetooth packet construction and deconstruction. This allows data written to the UART port to be transmitted wirelessly, and received Bluetooth data to be sent directly to your microcontroller, eliminating the need to manage complex protocols. Connection Roles The HC-05 module offers versatile connectivity through two primary roles: Master and Slave. In the Slave Role (default), the module remains discoverable and waits for external devices, such as smartphones, to initiate a connection—making it ideal for mobile-controlled projects. Conversely, in the Master Role, the HC-05 actively scans for and initiates connections with other Bluetooth modules, enabling direct wireless communication between two microcontrollers. Switching between these roles is easily managed by entering AT Mode and sending configuration commands via the UART port. Power and Logic Levels The HC-05 module features an onboard linear regulator, allowing it to be powered by a voltage range of 3.6V to 6V, despite the core chip operating at 3.3V. However, it is critical to remember that the module utilizes 3.3V logic levels. Because the RX pin is not 5V-tolerant, connecting it directly to a 5V microcontroller (like an Arduino UNO) can cause damage. To ensure safe operation, the microcontroller's TX signal must be stepped down to 3.3V using a voltage divider or level shifter. Additionally, current consumption varies based on the operational state, ranging from small idling currents to higher peaks during active transmission. AT Mode AT Mode is the dedicated configuration environment used to modify the HC-05 module's internal settings, such as its name, baud rate, and password. To enter this mode, you must press and hold the onboard button while powering up the module; a slow, steady LED blink confirms the transition. Once active, the module accepts Hayes AT-style commands (e.g., AT NAME=MyHC05) via the UART port. It is important to note that AT Mode typically operates at a default baud rate of 38400 bps, which may differ from your standard data transmission speed. This mode allows for full customization and status queries before returning to standard data communication. Pinout Configuration The HC-05 module breaks out six pins for power, data, and control. Below is the detailed functional breakdown: Pin Name Description STATE Status indicator; output is LOW when unpaired and HIGH when connected. RXD Receives serial data; not 5V-tolerant (requires step-down to 3.3V for 5V systems). TXD Transmits serial data to the microcontroller's RX pin. GND Common ground for both power and signal. VCC Power input (3.6V to 6V) for the onboard 3.3V regulator. EN Enable pin; pulled HIGH by default. Pulling it LOW disables the module. Control and Wiring Guide with Arduino Complete the hardware connections as shown in the diagram, then upload the code from this Arduino Code to start communicating wirelessly. Controlling the HC-05 is straightforward as it acts as a "data pipeline," wirelessly transmitting any serial data received via its RXD pin and outputting incoming Bluetooth data through its TXD pin. To set this up, you simply need to connect the module to a microcontroller's UART interface and pair it with a Bluetooth-enabled device (like an Android phone using the Serial Bluetooth Terminal app).  For Arduino users, it is recommended to use SoftwareSerial on digital pins (e.g., D2 and D3) to avoid interference with sketch uploads on the main hardware serial pins. While the VCC connects to 5V and GND to ground, you must use a voltage divider (a 1kΩ and 2kΩ resistor) to step down the Arduino’s 5V TX signal to 3.3V before it reaches the HC-05's RXD pin to prevent hardware damage. Application Wireless communication between microcontrollers Home automation Robotics and embedded systems Serial data transfer between devices Remote control applications Documents Arduino Code Serial Bluetooth Terminal Packaging Details 1x Bluetooth Module HC05 Master Slave Support Why Choose This Bluetooth Module HC05 Master Slave Support?  The HC-05 Bluetooth Module is a compact, versatile wireless solution, supporting both master and slave modes with stable 2.4GHz connectivity. It integrates UART communication and GPIO control, making it ideal for robotics, automation, and     remote-control applications. Warranty and Replacement TechShopBD offers up to one year of warranty and replacement support for its products, depending on the supplier(s) and product(s). The specific warranty duration for each product can be found on the respective product page. To be eligible for warranty and replacement support, customers must agree to our terms and conditions. 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