Bluetooth Module HC-05/HC-06 Arduino Wireless Series Port TX RX Module HC05 HC06 IOT Remote Control DIY Techmakers

HC-05
This is the popular Bluetooth module, HC05 which can be configured as master or slave.

Master Bluetooth will be able to search for other Bluetooth devices and initiate a connection.
Slave Bluetooth cannot search for other Bluetooth devices and can wait for the master to initiate a connection and accept the connection.
Features:

- Bluetooth v2.0+EDR
- 2.4GHz ISM band frequency
- Supported baud rate: 9600, 19200, 38400(default), 57600, 115200, 230400, 460800
- Speed: Asynchronous: 2.1Mbps (Max) / 160kbps, Synchronous: 1Mbps / 1Mbps
- Power Supply: 3.6VDC to 6VDC
- Passkey: 1234
- LED flashes = Bluetooth is connecting
- LED on = Bluetooth is connected
- Communication range: 10 meter

HC-06
It is only a slave device unlike the hC-05 which can act as a Master/Slave. This means the HC-05 can initiate a connection to another device and the HC-06 can only accept a connection from another device. Once it is paired to a master Bluetooth device such as PC, smart phones and tablet, its operation becomes transparent to the user.The HC-06 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. A logic level converter is recommended to protect the module if connected to a 5V device.

Features:
Bluetooth v2.0+EDR
2.4GHz ISM band frequency
Supported baud rate: 9600(default), 19200, 38400, 57600, 115200, 230400, 460800
Power supply: 3.6V to 6V DC
Passkey: 1234
Dimension: 3.8(L) x 1.5(W) x 0.225(H)cm