I want to use the 315Mhz transmitter with a mega8. I also want to use another similar device in conjunction with it, that requires address and command bytes from the usart. The other device is an SRF02 ultrasonic rangefinder.
Can I hook them up in parallel and rely on start and stop bits at the reciever end, or do I need an external buffer of some sort , or is there a way to code it?
if the 315MHz transmitter is a simple on/off keying transmitter, I think you’ll need a fair amount of code to generate the proper serial data stream for this transmitter, error detection and correction and all the rest that goes with wireless. And the reverse on the receiving end.
Or, if you are sending just a few on/off bits, you can use an encoder/decoder chip pair such as Holtek.
http://www.rentron.com/remote_control/Holtek.htm
It’s daunting.
That’s why folks often pag the $20 or so for a full-up transparent “wireless mode” like the Digi XBee series 1.
One of the better encoding methods is Manchester for an ASK transmitter. It does take more work in software but the RF hardware is simpler. Plus error detection and packetization.