How Master and Slave concept works with Bluetooth?

Question

From what I understand the master has primary control over the slaves and communicates with them. A master must always be present as well, and can be connected to (up to) 7 slaves.

Question

• If I have 2 arduinos with Bluetooth communicating with each other from within a radius of 80 meters or less, which arduino do I set as the master and which do I set as the slave? (what dictates which one should be set as master, etc.)

I want both arduinos to be able to transmit data to one-another (where neither has privilege over the other), so in my mind this is more like two slaves communicating. Both devices have the same controls on them and will effect the other devices the exact same way.

• How does the communication process work exactly, and how should more arduinos be addressed if they are to be added with similar privileges?

Answer 1

Well, master/slave concept for Bluetooth resides on the protocol, not in the communications. On few words, this means Bluetooth Master is who has the ability to initiate connection with a peripheral (or slave), but onces connected both master and slave basically can interchange information without restriction (limited by application). If your bluetooth module or implementation has a SPP (serial port profile https://developer.bluetooth.org/TechnologyOverview/Pages/SPP.aspx) once the master finds and connect to the slave, information can flow in both ways like a chat (actually, chat application is the most common usage example of bluetooth modules)