microcontroller RF communication

Sam Vimes

i'm trying to get two microcontrollers to talk to each other using this RF transmitter/receiver pair. i've never done RF communication with microcontrollers before so its a bit daunting. i've seen something about using manchester coding in BASIC but it needs to be in C and all google will turn up is seminars about C that are taking place in manchester

can anyone point me in the right direction to find out about microcontroller based RF communication?

i can't remember which pic i was going to use now. it was an 8 bit flash memory one from microchip. i have a C compiler and devlopment kit for it which is why it has to be C. any help appreciated

satchmo

A search for Manchester encoding will probably turn up more relevant results - the Wikipedia entry is always a good place to start.

DublinDilbert

Yes manchester encoding is often used when sending data via RF, especially if your sending long streams of bits, as it has a clock embedded into it, hence it stops the Transmiter and Reciever faling out of SYNC.

Alot of car alarm remotes use ASK modulation with the digital data machester encoded.

I take it your designing your own protocol, to get data from one point to another, one thing that you have to think about is that RF is a very un-reliable medium, hence good error detection is very important, so use a good CRC. If it's a college project you'll get lots of extra marks if you add in some error correction (hamming code ect)..

It dosn't matter which PIC your using, they are all pretty much the same.

If i had to send the data via manchester encoding, i would set an interrupt up at twice the bit rate on the transmitter, this will allow you to create a manchester encoded data stream at the correct bit rate. A state machine called by the ISR would do this neatly

On the reciever your best of measuring the width of the pulses and deciding where in the machester bitstream you are, and if the bit is a 1 or a 0...

hope this helps...