There are a few things to consider when buying a Bluetooth interface.
- A HC-06 can only operate as a slave. A HC-05 (which is exactly the same hardware, but different firmware loaded) can be a slave and a master.
- Watch out if you buy these, for normal 2.54 mm spaced boards, you need a little host board. Read carefully when ordering, ou want a module PLUS host boards, not just one or the other.
How to make a HC-05 a slave module
- Connect to the module, either from an Arduino or a UsbToSerial Adapter, ensure 38400 bps
- Boot while pin 34 of the module is connected to 3.3V. This will put it in command (AT) mode
- AT+ORGL (answer should be OK) set to factory default
- AT+NAME=1234 (OK) set the BT name of the device (1234 is an example)
- AT+RMAAD (OK) remove all previous pairings
- AT+PSWD=1234 (OK) set the BT password (1234 is an example)
- AT+ROLE=0 (OK) set the module in slave mode
- AT+INIT connect with this profile
Now reboot with pin 34 connected to ground.