I've just received rf link kit (http://www.seeedstudio.com/depot/2km-long-range-rf-link-kits-w-encoder-and-decoder-p-321.html?cPath=2), but now I realize that it's not working as I expected it to work. Actualy it does not do anything but indicates on receivers last pin that some signal is received when I power both modules up and try to give some input signal in transmitters side. So I guess I have to pair these modules some how. Am I right? I read on that site something about soldering corresponding pins of each module, but actualy I have no clue what do they mean by that.
Basically, you have to create solder bridges on both the transmitter and receiver pair for an "8-bit" code that matches, so that only the receiver with the same code as the transmitter is used. So, come up with a code for both, and solder the corresponding bridges from the center pads to the left (bit=HIGH) or the right (bit=LOW). For example, if you wanted both transmitter and receiver to be on address "129", the bit code is "10000001" (bit 1 is least significant here, the rightmost bit), so you would solder bit 1 (shown at the top of their pic) from the center pad to the left pad, bits 2-7 from the center pad to the right pad, and bit 8 from the center pad to the left pad - you would do this for both the transmitter and receiver.
You could also wire up an 8 switch DIP switch in such a manner to allow you to set the code with switches; you could also have the Arduino "set" the code (via digital I/O) - so you could communicate with multiple transmitters and receivers if you wanted (n-n way communication possibilities).
Hope that helps...
Yeah, now it works, thanks!
Good to hear!
I have read elsewhere that these kind of serial RF transmitter/receiver pairs can be "flaky" in their operation; I think somewhere out there on the internet (sorry, no link handy) there was talk about using Manchester encoding or something to increase reliability...?
YMMV.
Here are some links regarding Manchester encoding - not sure if they are the same from what I read, but they may help:
http://www.electronicspoint.com/manchester-biphase-protocol-avr-microcontrollers-t22334.html
http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=53718&view=previous
A google search on "Manchester", "encoding"/"decoding", "microcontroller", and/or "avr"/"pic"/etc will bring up more links that may be helpful.
Also - an interesting Atmel app note (may or may not apply):
Wow, what an great information, thanks a lot!