Bluetooth master or slave?

I'm admittedly new to all of this, but what I want to do seems simple enough. I want to e able to turn a light on when a bluetooth device comes in range.

All that the main unit will need to do is scan for devices periodically, and check the ID/mac address if it detects a device. There should be no need to actually pair with it. All I need it to do is to know that this is my phone and not some other one.

Since I am not actually connecting to the device would a slave module be sufficient?

tbradt: Since I am not actually connecting to the device would a slave module be sufficient?

No, the firmware of the slave does not allow you to list BT devices.

EDIT: Just powered up a BT master module and I can detect my phone when it's BT is set to discoverable using the AT+INQ command and when I hide the phones BT and do another INQ it times out after about a minute and returns just OK. The timeout can be shortened by reducing the maximum number of devices to scan for (default 48)

Thanks.

I wouldn't be doing an inquiry because I don't need to find unknown devices. I had planned to do something like a name discovery using the device ID since I already know which device(s) I will be looking for. That should work even if the phone is not in discovery mode shouldn't it?

I'm guessing I would still need a master for that?

tbradt: I had planned to do something like a name discovery using the device ID since I already know which device(s) I will be looking for. That should work even if the phone is not in discovery mode shouldn't it? Just tested this and it does work even if phone BT is hidden. I'm guessing I would still need a master for that? Most probably yes, the BT modules I'm using don't have AT command to read remote device name.

Excellent! Thanks a bunch.

I've been looking up modules over the last few days and every time I think I've settled on one I find info that makes me second guess it. Do you (or anyone) have any recommendations for a decent inexpensive module?

I've looked at the RS232, but I keep finding references to needing other hardware and drivers to run it. Is that the case?

Also looked at the Virtuabotix BT2S-M, but for some reason it says it requires the slave to communicate between devices. That seems really odd. If it's bluetooth it should pair with pretty much any compatible device, right?

This is just getting more and more complicated. Fortunately the RF portion of the project seems to be going more smoothly.

Sorry for the delay,

tbradt: I've been looking up modules over the last few days and every time I think I've settled on one I find info that makes me second guess it. Do you (or anyone) have any recommendations for a decent inexpensive module? I bought a couple of these. You may need a few extra components to level shift between 5V and the 3.3V the module uses.

I've looked at the RS232, but I keep finding references to needing other hardware and drivers to run it. Is that the case? For me some resistors to do level shifting and a LED/resistor for status. Only drivers I needed on arduino was SoftwareSerial.

Thanks for the reply. I ended up getting pretty much the same thing, but already soldered and ready to be plugged into a breadboard. I figure that, as a beginner, that would be the way to go. I already have enough to try and figure out as it is :slight_smile: