HC-05 With Firmware 2.0-20100601
There are now many cheap and no brand HC-05 modules that use the 2.0-20100601 firmware and rather than keep making the same post for different modules I will have a single main post which, as I update and add to it, will become a single point of reference.
HC-05 with firmware 2.0-20100601
The 2.0-20100601 firmware is originally by HC/Wavesen and as the version number may suggest it is from 2010. I am not sure if other manufacturers use it under license or simply copy it since the genuine HC/Wavesen modules now use version 2.1 firmware.
HC-05HC-05 with 2.0-20100601: AT Command ModeHC-05 with 2.0-20100601: Connecting to an ArduinoHC-05 with 2.0-20100601: Initial Communications TestHC-05 with 2.0-20100601: Main AT CommandsHC-05 with 2.0-20100601: AT Commands Dealing With ConnectionsHC-05 with 2.0-20100601: Making A ConnectionDownloads
The 2.0-20100601 firmware has a fairly long list of commands. Some perform common functions and others you may never need. Here are some of the more useful/common commands. Remember that some commands need pin 34 to be HIGH. I have tried to highlight this but may have missed some. If you are using the button switch and do not get a reply, try closing the switch and send the command again (while keeping the switch closed).
The HC-06 is a slave only BT module that is fairly easy to use with the Arduino using serial communication. Once it is connected it simply relays what it receives by bluetooth to the Arduino and whatever it receives from the Arduino it sends to the connected device. There are several slightly different versions of the HC-06, however, all seem to use the same firmware and have the same AT commands.