AVR-Chat

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