Re: TINI wireless link - IR or RF?

Bruce,

On 06/29/04 17:23:21, Bruce Boyes wrote:
> Quoting Jim Redman <jredman-wAA+5nrAsfVWk0Htik3J/[email protected]>:
> > I have no idea what Christian Lorenz used to test the stack on the
> > TINI.  The CF (or PCMCIA) cards that he lists on his site register
> > themselves as serial ports and the stack is based on javacomm.
> > There are BT adapters with a DB9 which should work.

> There you go. That's only a very uninteresting, point to point
> hardcoded serial adapter only version of BT.

I think that there's some confusion here.  The BT adapters identify  
themselves as COM ports, but that doesn't mean they're restricted to,  
say, just the RFCOMM protocol.  The full BT stack is available through  
the interface (via the "H4 (UART) HCI Transport Specification"?).   
They're much more than point-to-point, it's most of the JSR-82  
implementation.  Ironically, it's missing RFCOMM (the point-to-point  
serial emulator), which is the protocol of interest to me.

These are the same cards as used by, for example, BlueZ for Linux.   
They also have Windows support you can use them as part of any BT  
network.

The only restiction of using a UART as the interface is that the speed  
of the BT interface is throttled to the maximum speed supported by the  
UART, typical 200K baud+.

(There are some RFCOMM only cards, for example IONetwork's WaveSpeed).

> I don't own a single BT device. Hmmm, I wonder why? Maybe it's that
> there is nothing useful to do with it?

My particular application is to put a BT adapter on a bunch of PLCs and  
so use, say, an IPAQ to interface to the PLCs.  You can walk up to a  
remote installation and communicate without opening the cabinet.   
There's a saving here since you can do a "drive-by" without actually  
getting out of a vehicle.

The problem is that the cost of, eg 802.11, is about the same as BT.   
So for application like this it's hard to justify why it should be BT  
and not wireless ethernet.  The modern IPAQ's have both 802.11b and BT,  
I haven't even tried the BT adapter yet.


Jim


-- 
Jim Redman
(505) 662 5156 x85
http://www.ergotech.com
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