Bluetooth between two boards


I have an Arduino Mega which I can control via an Android smartphone. I use a HC-05 bluetooth receiver for that purpose.

Here's my question: I would like to connect "board 2", an Arduino Uno via bluetooth to "board 1", the Arduino Mega. So in the picture below I need a own receiver for "board 2".

But can I use the current HC-05 receiver of "board 1" or do I need a second HC-05 receiver to connect "board 1" to "board 2"??



Since the Mega has four serial ports, the simnplest approach would be to install a second HC-05 to talk to Uno.

I think you could use the one HC-05 but it will involve some pretty fancy programming.

Bluetooth devices pair. Pair means two devices taking to each other. If the one bluetooth device connected to the Mega is talking to the phone, it can NOT talk to the other Arduino at the same time.

So I need a second Bluetooth Receiver to communicate to a second Arduino ?

I believe you can programme the one HC-05 to unpair, go into AT mode configured to autoconnect with Uno, go to comms mode, and tralala. It is essentially just a matter of applying a signal to the key pin, which is not normally used for operations. But with all that for saving the cost of $3-50 for a second HC-05, I'm sure it isn't worth the effort, particularly when you are using a Mega.

Yeah, you're right. And furthermore, when one receiver crashes, I still have one piece of connectivity left. The probability isn't high, but in case it happens, this is better.