The HC-06 is a very common and oh-so-useful Bluetooth Module that forms part of the HC Bluetooth Series.
Its most common use is to be a transparent serial port connection computers and devices. It can be simply
used as a drop in place device to establish links between MCU's an GPS controllers or Phones to Arduno boards,
It can even be used for allowing your Marlin Compatible 3D Printer to communicate via Bluetooth instead of
pesky USB Cables.
Bluetooth protocol: Bluetooth Specification v2.0+EDR
Frequency: 2.4GHz ISM band
Modulation: GFSK(Gaussian Frequency Shift Keying)
Emission power: =4dBm, Class 2
Sensitivity: =-84dBm at 0.1% BER
Speed: Asynchronous: 2.1Mbps(Max) / 160 kbps, Synchronous: 1Mbps/1Mbps
Security: Authentication and encryption
Power supply: +3.3VDC 50mA
Working temperature: -20 ~ +75 Celsius
Dimension: 26.9mm x 13mm x 2.2 mm
Default Baudrate: 9600
Here are some really neat little projects to explain how this module works!
AT Command List