[Refik Hadzialic] has updated is site with a how-to that could be rolled into many different projects. Using a receiver and transmitter pair from Laipac he demonstrates how to communicate wirelessly between two microcontrollers. The pair costs about $12 and operates at 315MHz. He’s got a chunk of commented code in the article to give you an idea of how it works.
I was just thinking about something similar a few days ago…
While the Laipac RF modules used in this project (http://www.sparkfun.com/commerce/product_info.php?products_id=383) are ok, they lack any sort of preamble or error-checking that would make transmission reliable. Data transmission without significant microcontroller-based error checking is iffy at best because of noise on the UHF frequencies. A much better RF solution uses the RF-24G transceivers based upon the nRF2401A chipset (http://www.sparkfun.com/commerce/product_info.php?products_id=153). They are bi-directional and only cost $12.95 each (store.qkits.com/moreinfo.cfm/TXRX24G), a much better buy! I’ve used the RF-24G for a number of projects (http://www.semifluid.com) and have had great success with it.
That is pretty sweet..
Derek
yay post #3
I can personally recommend the modules from telecontrolli (www.telecontrolli.com). The RXQ2 module, for example, is a _transceiver_ (so both transmitter and received in the same package), can select between 255 different channels (very narrow band), and also has on-chip address recognition / CRC generation and verification. And it’s priced at only 20 euro per piece! I don’t have any connection with telecontrolli whatsoever, but I never found a RF transceiver _module_ at such a low price. Internally, it is based on the excellent nRF9E5 chip from Nordic (www.nvlsi.com). Highly recommended.
I haven’t used them yet but the Nordic nRF-blahblah chips look really great. The sparkfun module is priced about the same as the telecontrolli module, about $20/$25 with a builtin antenna (a nice thing at 2.5GHz, hard to make your own).
But the laipac modules can be had for cheap too: under $20 for a tx and an rx module ($5 + $15 or so).
Bluetooth modules can be had for about $50, which is more expensive, and they’re a pain to use, and the range isn’t great, *but* you can then talk to your project with any bluetooth-capable laptop or PDA, which is nice.
#6, Spark Fun carries the Laipac nrf2401a transceivers (http://www.sparkfun.com/commerce/product_info.php?products_id=151) that are sold at qKits for about $8 cheaper (http://store.qkits.com/moreinfo.cfm/TXRX24G). They are exactly the same modules. I actually bought the qKit’s transceivers and got 2 breakout boards (http://www.sparkfun.com/commerce/product_info.php?products_id=196) for my hobbying.
Nice, but they’re really not the same thing. The range thingy is misleading. It’s the LOS (Line Of Sight) range, which means the range that can be achieved between two transceivers that cat “look” directly at each other, without any obstacles in their way. This becomes very important at 2.4GHz, because microwaves are VERY directional. Any tiny obstacle in their way can seriously limit their performance. The devil is always in the details :)
I used the very same modules in my Ambient Orb lookalike color-changing taplight:
http://devices.natetrue.com/wlcolor
Do you have CTS/RTS diagrams/information for telecontrolli RXQ2?