HC05 Wireless Bluetooth Module

The HC-05 is a class 2 Bluetooth module designed for transparent wireless serial communication. It is pre-configured as a slave Bluetooth device. Once it is paired to a master Bluetooth device such as PC, smart phones and tablet, its operation becomes transparent to the user. No user code specific to the Bluetooth module is needed at all in the user microcontroller program.

The HC-05 supports two work modes: Command and Data mode. The work mode of the HC-05 can be switched by the onboard push button. The HC-05 is put in Command mode if the push button is activated. In Command mode, user can change the system parameters (e.g. pin code, baud rate, etc) using host controller itself of a PC running terminal software using a serial to TTL converter. Any changes made to system parameters will be retained even after power is removed. Power cycle the HC-05 will set it back to Data Mode. Transparent UART data transfer with a connected remote device occurs only while in Data Mode.

The HC-05 can be re-configured by the user to work as a master Bluetooth device using a set of AT commands. Once configured as master, it can automatically pair with a HC-05 in its default slave configuaration or a HC-06 module, allowing an point to point serial communications.

The HC-05 will work with supply voltage of 3.6VDC to 6VDC, however, the logic level of RXD pin is 3.3V and is not 5V tolerant. It can be damaged if connect directly to a 5V device (e.g Arduino Uno and Mega). A Logic Level Converter is recommended to protect the HC-05. The power to the HC-05 will cut off if the “EN” pin is pulled to logic 0.

Specifications :

• Bluetooth v2.0+EDR
• 2.4GHz ISM band frequency
• Supported baud rate: 9600 (default), 19200,38400, 57600, 115200, 230400, 460800.
• Speed: Asynchronous: 2.1Mbps(Max) / 160 kbps, Synchronous: 1Mbps/1Mbps
• Power supply: 3.6V to 6V DC
• Passkey: 1234