Bluetooth support for multiple serial connections?

Forum 2005-2010 (read only) Hardware Interfacing
1

Does the bluetooth module in the Arduino BT support multiple serial connections? What I'm trying to do is establish multiple serial data streams (resulting in multiple ttys/virtual com ports on the computer end) using a single bluetooth module.

Bluetooth supports this, but the various implementations seem quite limited (e.g. only 1 serial connection allowed). I was wondering if someone has tried this with the WT11 module in the Arduino BT.

-j

2

we had two bluetooth arduino's connected to one computer..... both were controlled in max|msp, i suspect you can pair and connect with more (we only have two)

so it is possible
-n

3

Thanks, but I'm not trying to use more than 2 bluetooth unis at the same time (piconet?). I need to put multiple rs232 connections (SPP) on a link between a single pair of bluetooth devices, largely so that I don't have to spend US$70 per bluetooth endpoint. I'm trying to reduce the cabling complexity of a mobile computing rig without spending US$350 on bluetooth modules.

The bluetooth standard supports multiple connections across the same bluetotoh link (up to about 60, IIRC), but apparently not all vendors choose to fully support that.

It's beginning to look like I'll have to multiplex the data streams, then demux them on the computer using a bunch of pipes/ptys. Ugly, but the only other solution I've got is customizing the application, and that's a lot more work for less return.

I am finding bluetooth extremely frustrating. That standard allows for many things, but only a few seem to be supported by most vendors. The devices are obscenely expensive. Lantronix now has an 802.11 module with serial interface for about US$70, the same as the price of a typical bluetooth module. Sparkfun has the Nordic units which, while slightly shorter in range than bluetooth, are only US$20 each. Why does a USB Bluetooth adapter for your laptop cost as little as US$7, but a bluetooth module with no power regulation, no antenna and no enclosure cost $70?

-j

4

the arduino BT supports up to 7 simultaneous connections...

check out the IWrap manual ( the firmware that runs inside the arduino bt) and look specifically at the "multiplex" mode which simplifies dealing with multiple connections

massimo

5

Thanks Massimo. This looks like a custom data mux/demux solution rather than actual support for multiple SPP/RFCOMM connections. Has anyone used this feature yet?

thanks,
-j

6

hello

Did you find the solution? I was wondering if it is possible to have more than 1 SPP (serial) connections.

Thanks

7

I haven't found anything short of implementing a significant chunk of the bluetooth protocol stack (which I have no desire to take on).

All of the bluetooth modules I've been able to find are similar to the one used by the arduino BT in that they only support one serial connection.

-j