Product details
Hardware Overview
The HC-05 is a Bluetooth-to-Serial-Bridge module that allows wireless communications between two microcontrollers or between a microcontroller and a smartphone, laptop, or desktop PC with Bluetooth capability. It’s perfect for directly replacing a wired asynchronous serial interface!
Each of these modules contains a Bluetooth transceiver, meaning they’re capable of both sending and receiving data.
As a Class 2 Bluetooth device, the HC-05 has a nominal range of 10 m. Of course, that is out in the open. Its range gets a little weaker inside the house, especially because of the walls.
To top it all off, these modules are very easy to use. There’s no need to mess with Bluetooth protocols or the stack. Just send data over a serial interface, and it’s piped through to whatever Bluetooth device it’s connected to.
Modes of Operation
Controlling the HC-05 module and sending data through it are two different operations, but they are both accomplished through the serial interface. To distinguish between these two types of data, the HC-05 employs two distinct communication modes: AT mode and Data mode.
In AT Mode, you can configure various settings of the HC-05 module, such as its name, baud rate, PIN code, and data rate.
In Data Mode, the HC-05 module acts as a transparent data gateway. When the HC-05 receives data, it removes the Bluetooth headers and trailers and sends it to the UART port. When data is written to the UART port, the HC-05 constructs a Bluetooth packet and sends it over the Bluetooth wireless connection.
Connection Roles
The HC-05 Bluetooth module can function in two main roles: Master and Slave.
In Slave Role, the HC-05 module waits for other devices to initiate a connection. This is the module’s default role and is commonly used in projects where you want to control things using a smartphone.
In Master Role, the HC-05 actively searches for other Bluetooth devices and tries to initiate a connection. This mode is used in projects where two microcontrollers need to communicate wirelessly.
To switch between roles, you need to configure the HC-05 module by putting it into AT mode and sending AT commands over the UART port.
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