AVR-Chat

I'm a little confused. You said, earlier, I think, that you
are using manchester coding. That really does not fit with
"UART". Trying to use a UART with manchester seems like a
real problem. I'd do it all in software.

Jim

On Tue, 22 Mar 2005 13:39:40 -0300
 "Javier Fiasche" <jfiasche@tutopia.com> wrote:
> That's right the uart ist triggering on noise.
> Unfortunatelly my reciever does not have signal strength
> output. I am using
> a very cheap
> Yong Horng reciver and transmitter (not a transciver).
> I would need to detect a real transmition and to reject
> noise, but
> digitally, ideas???
> I tried transmitting a Hi level before setting the uart
> to transmitt, and
> trying to detect this continuos hi level on the reciver
> before setting the
> reciever uart to recive, But it doesn't work that
> fine............
> Thanks
> Javier
> 
> -----Mensaje original-----
> De: Bruce Parham [mailto:obparham@jpl.nasa.gov]
> Enviado el: Martes, 22 de Marzo de 2005 01:29 p.m.
> Para: AVR-Chat@yahoogroups.com
> Asunto: Re: [AVR-Chat] RF link
> 
> 
> 
> 
> Javier Fiasche wrote:
> >
> > Hi everybody, i'm having trouble.....
> >
> > I am trying to transmit data over Rf using 2
> atmega8l(via USARt) and
> 433Mhz
> > transmitter and reciver module. One will work as
> transmiter and the other
> as
> > reciever. The transmiter will send a code composed of:
> >         -----------------------------
> >        | SYNC |Package|CHECKSUM|end|
> >        -----------------------------
> > all of this coded as manchester. Afer sending the
> package, the mega8 will
> > shut down the transmitter until next transmition.
> > The reciever would listen to the reciver module only
> when it is desired,
> > selecting this with a pushbutton.When i dont want to
> listen, i shut down
> the
> > 433 reciver module
> > Here is the problem:
> >         i dont seem to sincronice the transmitter and
> the reciver usart,
> because
> > when the transmitter is off and the reciever is on i
> keep getting and
> > Framming error.
> >      i've tried listening to the RXd pin, with the
> RXEN=0, till i get a
> > long enought "1" and then set the RXEN=1, but this seem
> to have no
> > effect.........
> > Any ideas of how to sincronice them????????????
> >
> > Thanks
> > Javier
> 
> Sounds like the rx doesn't have any squelch and the uart
> is triggering on
> noise.
> I don't know what kind of receiver you're using but, if
> it has a RSS (Rx Sig
> Strength)
> line, you could use that to enable/disable the rx uart.
> (You may need to use
> the
> analog comparator on the RSS signal.)
> 
> Bruce
> 
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