Bluetooth module usage (JY-MCU)

I have arduino mega and jy-mcu bt_board v1.02 module. It has state, rxd, txd, gnd, vcc, key. I have no idea what these pin names mean and no idea what to start with. How to make it work with arduinocommander android? Thanks in advance!

I have one of those as well. It is simply a serial port "hidden" behind a bluetooth connection. You treat it as a serial device like any other in the arduino side.

To get it to work with Arduino, read this:

Use the SoftwareSerial library.

Now, in the Android side, you must pair (the JY-MCU device name is "linvor" and the default password is "0000"). there is an app called "Connection Terminal" that allows you to talk "serially" over the bluetooth connection.

I haven't done anything with serial connections, I'm overally a newbie to arduino and this stuff. Can you explain more detailly what do I have to do?

Try this: http://www.amarino-toolkit.net/index.php/getting-started.html

Good luck!