I have recently found that we need a security system in our home but am unwilling to pay a company $80/month to monitor and let them run wire all over the house. So I got to thinking that why can I not make my own simple mesh network and run it all off a head unit? (Possibly an old WRT54G router even)

My problem is finding an actual RF product for my needs. Battery life is #1 with size being a close #2 as these will be on windows and doors and can not be bulky.

I saw Synapse's SM200 which is a great size and has a fantastically easy python scripting language to work with but it seems that nobody stocks these things.

I looked down a scale of integration and see that the Synapse modules are based on a ATMEGA128RFA1 These chips bare however are quite pricey and I would still need a PCB and chip antenna.

Another Chip is Microchips rfPIC12F675F. These are much more affordable but are nearly impossible to find a stock of and even worse their is no official C compiler for this core (Not 100% sure, was just the word on some forums)

Ideally I would love to use the Synapse module as I doubt I could make my own board for cheaper but does anybody know where I can get these from? IF that's not going to work then are their any other RF solutions that meet my criteria? Possibly a separate RF IC that I can tie my favorite micro to?

Thanks for helping me out!


You could take a look at NXP's JN5148. Comes as a surface mount module containing micro, loads of I/O and RF, stacks for various flavours of RF comms including ZigBee and uses Eclipse as the development environment (supported under Windows). I've used it at work and eventually intend doing a load of automation stuff at home (i.e. when there's this mystical thing known as "spare time").

There are dev notes showing how to power them from a coin cell for low power intermittent use, and Farnell stock them.

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  • \$\begingroup\$ Thanks for the link that's a great little module, only two bucks more than the Synapse and the same size with a bunch of other interesting features. (The built in battery monitor is great!) And it seems everyone stocks these guys. I have a programming question though. It appears to use USART0 to program and toggling MISO and RESET to get it into programming mode, is it similar to the ARM's where you hold MISO low and reset to enter programming mode and then I could use something simple like a Bus Pirate to send the bitstream to ROM? \$\endgroup\$ – uMinded Jul 20 '12 at 2:48
  • \$\begingroup\$ Yes (well, I assume it's MISO- can't find a diagram at the mo). However you're probably better using the flash programmer they (freely) supply, since the MAC address is in flash as well and you might find it more effort than it's worth to shoehorn code in using a different programmer. \$\endgroup\$ – Craig Graham Jul 20 '12 at 7:39

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