My question is: Can I directly interface/connect the RX & TX pins of my arduino with the TX & RX pins of the BT module?
For now, this is a test setup. If everything is ready I would like to use an arduino mini or something. I don't know if this makes a difference?
The idea is that the voltage on one of the analogue pins is read and sent to a phone over bluetooth.
I'm new to electronics, so maybe a stupid question:
Isn't the arduino operating at 5V and the BT module at 3.3V?
So I presume the TX pin on the arduino uno will be transmitting a 5V signal?
And on the TX pin of the BT module, the signal should not exceed 3.3V? So I should place a resistor in between (voltage divider)?
The other way around, the BT module will be transmitting a 3.3V signal towards the arduino's RX pin. Will the arduino be able to interprete the 3.3V signal without a problem?
Yes, the HC-05/6 is 3.3V. The Arduino will accept the signal from the BT as is, but you should use a voltage divider on the Transmit to the BT from the Arduino to step the signal down to aproximtaly 3.3V. I have heard of people using the signal "as is" but do this at your own risk..... I use the voltage divider, there are many examples on the net of this circuit.
This depends on what you've got, and the link you show doesn't work. If your HC-06 is a single solder pad board with lots of little notches around it, it requires 3v3. If it is a sandwich of two boards it will run on 5v and is likely to marked to that effect, as all the level shifting, among other things, is done by the backboard.
If it is the former single smd board, the best thing you can do is get a backboard off eBay for about $3 and solder your module to that. You can then run it on 5v, have no worries, easily connect it, and get a LED for free.