Bluetooth devices

does anyone have any experience with them?

I am looking to develop a method to connect FROM a Fez not to a PC as most people would, but to a solar power inverter.

I’m making a few assumptions here, since I do not own this inverter (I’m researching this for a friend) and I haven’t been able to do diagnostics to answer some of the questions that I think I might need to.

So anyway, here’s what I am thinking (hoping) I need to do.

I am assuming this inverter offers a Serial Port Profile (SPP) for connection.

I am assuming that once a BT pairing is established between the inverter and the “other end”, I can communicate over the SPP.

I am assuming that two-way communication is handled over the SPP; and I can find the “instruction set” to post to the inverter to query it with.

So assuming the above, what I envisage is that I would have Fez plus a BT module connected to a UART; I talk to the UART on Fez, which talks to the BT module, which wraps the conversation up in the SPP channel, and it pops out at the inverter. (I may need a “control” mechanism to set up the module as well, that may or may not use the same UART; I’ve seen modules that use a $$$ “command mode” on the regular comms port for instance)

I have no bluetooth module(s) at hand and they’re expensive enough not to lash out and buy one on spec, in the hope that I can make it work. So I’m hoping someone will have had enough exposure to them to guide me further.

The one key question in my mind, is about pairing. Most modules I’ve seen used end up being paired with a PC, so all the heavy lifting is done in the PC’s BT software. I need a module that behaves as a “master” and can initiate the pairing with the remote device, and therefore needs to not just be a “simple” serial-port to BT module (which the GHI offered module appears to be).

Does anyone know of modules that can do this; or am I wasting my time here?

cheers in advance!

There are simple serial modules that also have commands to establish connections, they are still SPP profile. List of Bluetooth profiles - Wikipedia

The module we currently offer doesn’t have this but we had discussed tis internally and we may update them in future with modules that can do more.

Look at the document on this page

The module I used (see [url] can be put in master mode. It can then browse for other devices, get there capabilities and pair with them, with or without a pin, after which one starts the SSP profile then it becomes a serial pipe…

Granted, I have never tried to do this. But I did see in it’s “datasheet” that these things are possible.

I have used a number of devices:


But I keep coming back to Sena ( For pure SPP communication they are the most reliable and easy to use. Good support too. You can do all the things Errol mentioned too via AT commands. Also, they support multiple slaves for parallel dispatch of data to multiple devices. Very cool.


thanks for the thoughts and confirmations. “Master” mode is what I am after so I can manage the connection (not knowing the lingo was certainly a barrier to start my research!)

I’ve found a project to talk to this inverter over bluetooth from linux and it uses BT sockets and RFCOMM (well from what I read into the code that’s what it uses :slight_smile: ). I think I have to dig more into capabilities of these modules to see if it’s going to be worthwhile pursuing further.