Sorry to reply again,

But if its a security sensor, and the sensor is tripped, just
continually broadcast that its tripped.

andrew

On 2/11/06, andrew kelley <leetslacker@gmail.com> wrote:
> If they don't have receivers built into the modules, you're pretty up
> a creek without a paddle (well unless you add a receiver to each
> module which increases the cost), but you could make your information
> protocol have an Sequence number field and randomly adjust the
> interval between packets.  Also you can transmit every packet twice
> with the same sequence number so the controller doesn't get confused
> or think its seen two packets.
>
> if newseq <= curseq dump packet
> if newseq > lastseq keep packet
>
> If the chips do have receievers, make the sensors transmit, then if it
> doesnt hear an Acknowledge (with unit #) back within X ms then
> retransmit.  You could also decide if the information needs to be
> retransmitted as is or if you want to wait for an update.
>
> andrew
>
> On 2/11/06, Dumitru Stama <list@mirosat.com> wrote:
> >
> > Hello guys,
> > I want to implement a few wireless sensors in my home and i was
> > thinking about using nordic-based modules like the ones sold on
> > sparkfun.com. My question is how can i implement a working
> > anti-collision communication between the sensors and base station ?
> > If three sensors broadcast at the same time then i might have a
> > problem. I was thinking about a token sent by the base station to one
> > sensor after which it waits a period of time for the feedback and then
> > move to the next sensor and so on. Is this a good way of doing things?
> > I can also detect if on sensor has been disabled very easy and maybe
> > (if it is a security system) to issue some warnings if the problem
> > is still there after a few minutes or a few unsuccessful tries.
> >
> > Dumitru Stama
> >
> > --
> > http://www.piclist.com PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
>

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist