Best and Cheapest source of RF home automation communication chips

Question

I'm trying to find the best/cheapest source for Wireless communication.

I'm focusing on Home automation.

Zigbee stands out in my mind, but I look at the modules, and they are ~$20

since I live in a world were I can connect anything to anything. I would need 20 - 100 or more, of these things.

making $20 a little to much.

I notice the chips aren't to bad. but I'm not super great at rf board design. My main experience is with digitial.

I also have seen some $2-$5 modules on ebay, but not sure how reliable they are.

I don't have a problem comming up with my own communication protocol like ANT+.

What are some of the best resources for accomplishing this task?

thanks for your help and suggestions.

bobbaddeley · Accepted Answer

If you are looking for a single solution for a hobby, then you might be able to get away with those cheap RF modules on eBay. If you are looking to develop a product for sale, then don't give up on those Zigbee modules too quickly.

One of the reasons the Zigbee modules are expensive is because Zigbee is a standard and products that use it are members of the Zigbee Alliance, which has a yearly membership fee that's not cheap. If you want your product to interface with other Zigbee products already installed in a home, then you are best sticking with a standard others already use, and that means either developing a product and joining the Alliance, or purchasing the more expensive solution.

Another major reason is certifications. FCC certification can easily cost upwards of $10k, and IC, ETSI, Japan, and other countries can all be just as much. By choosing a solution that already has FCC certification, you're avoiding those costs.

If you are OK with skipping Zigbee, you should look into Microchip's MiWi, which uses the same frequency but is a royalty free stack. Check out the MRF24J40MA, which is $10 in single quantities but gets down to $6 in large volumes. When paired with a PIC microcontroller, you can run the MiWi stack and have a module that meets all the FCC/etc. certs and doesn't have all the expense of Zigbee.