Serial communication between multiple nodes using Bluetooth

[emontllo]

Hello!

I am developing a system that requires wireless serial communication between 5 nodes using Bluetooth.

The system has one “Bluetooth master” and 4 “Bluetooth slaves”. Bidirectional serial communication must be established between the slave and the nodes. From a functional point of view, the system should be similar to a daisy chain connection RS-232 bus (i.e. the communication channel should be always ready for the slaves if the bus is free).

Is it possible to develop such structure using OEM Bluetooth modules? (I have been looking to Lair Technologies BTM411 and BlueGiga WT12-A-AI) Any recommendation?

Is there any limitation when interfacing various nodes with serial communications?

Thank you for your responses!

 

[jrowberg]

I am not familiar with the BTM411, but I have used the Bluegiga WT12-A extensively and can vouch for its suitability for this purpose. (I have worked with it for two years on my Keyglove project, and I actually started working at Bluegiga as an FAE this past October.)

The WT12's iWRAP firmware supports multiple profiles at the same time, including SPP. Additionally, it has a mode called "MUX mode" which allows for very easy management of multiple links at the same time. The documented limit to simultaneous links with iWRAP is 7, so you should be able to do 4 easily. The only issue you might run into is if you have very high throughput requirements, since MUX mode imposes some overhead for link management. But this is true in any system; there will be a cap on just how much performance you can push out of a single RF transceiver. You'd have to provide a little more info on the particular use case to say for sure.

Bluegiga has a lot of documentation and app notes, and the iWRAP firmware is well-established and very capable. Feel free to take what I say with a grain of salt since I do work for them now, but that only came about because I was tremendously impressed with the products and support as a customer myself first. If you give the WT12 a shot, I think you will be pleased.