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ybox2 + CC2520

Wednesday, July 21, 2010 by darco

I just wanted to share some pictures of another aspect of the same home automation project.


What I'm doing here is connecting a TI CC2520 802.15.4 transceiver to a ybox2, using a break-out board that I designed a few months ago. I'm in the process of developing the CC2520 driver for the Propeller now, and hope to have it working in a week or two. After that, I'll be developing a 6LoWPAN stack for the propeller chip. Fun times.

So what are the possibilities?

  • 802.15.4 tunnel, for connecting two Zigbee networks in different locations.
  • 6LoWPAN to ethernet bridge.
  • 6LoWPAN border router.
  • TV-based 802.15.4 network monitor

I'll be exploring all of these options in the weeks to come.

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Tuesday, July 20, 2010 by darco

I finished placing all of the components on my CC2530-based XBee clone a few days ago. Tests using SmartRF Studio indicate that the chip is fine and working properly.

Not sure about how well the radio works yet, since it seems that my initial layout is going to lead to significant signal attenuation. Hopefully it won't be too bad. I'm new to all this RF stuff.


I'm now dubbing it the FauxBee. Note the lower case 'X', to avoid any trademark confusion.

It turns out I had the wrong landing pad for the crystal—my 32MHz crystals were a tad large. I went out to HSC Electronic Supply and picked up the closest thing I could find. The new crystal just barely touched all the pads, but it does work!

Most of the decoupling caps are on the other side of the board.

Now the hard part: porting Contiki to this thing.

Soldering a QFN

Wednesday, July 14, 2010 by darco

A while back I got my CC2530-based XBee-clone boards back from BatchPCB. Then reality set in—I actually had to solder these things! After much trial and error, I think I finally have figured out the right technique using solder paste, flux, and hot air. Here are some results:

IMG_0063 IMG_0065

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Projects Sneak Peek

Friday, May 28, 2010 by darco

Here are some teasers for the home automation and wireless sensor network project I'm working on.


This is a prototype appliance module driver board, supporting both the CC253x Breakout boards as well as the inexpensive XBee modules. This board has footprints for using either a bistable (latching) relay or a solid-state relay. Has optional support for load-sensing (for local control or burn-out detection), zero-cross detection (for dimming), and inductive current sensing. It has headers for two input buttons and two indicator LEDs.


This is a breakout board for the TI CC2520 2.4 GHz IEEE 802.15.4 RF transceiver. If the bottom header is populated, it can be used with the CC Debugger as a 802.15.4 sniffer. My primary motivation is to make it easier to work with the CC2520 as I develop a 6LoWPAN border router. You can grab the eagle sources to this board here.

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CC253x Breakout Board

Friday, May 21, 2010 by darco

One of the things I've been working on in my spare time is a breakout board for the CC2530/CC2531 low-power system-on-a-chip microcontroller with a built-in 802.15.4 radio. This is a great chip, but without an easy-to-use breakout board it is somewhat difficult to prototype with. So here is mine:


Front and Back view


Combined View

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ZigBee vs 6LoWPAN

Wednesday, May 12, 2010 by darco

While it's a post from way back in 2009, I think it is worth pointing out—as it seems more relevant than ever:

Think about it. The Internet… the most successful, innovative, massive network ever created. Now what was that Zig thing called again? Does anyone even remember the proprietary, link-specific networking protocols from the 90s?
[ZigBee vs 6LoWPAN?]

The more I read about ZigBee the more I think it is not the direction low-power wireless mesh networks should be going. 6LoWPAN stacks are smaller, just as efficient on the wire, and infinitely more scalable and flexible. ZigBee may tout itself as an open standard, but how open can it be if you can't even license an open-source ZigBee stack under the GPL?

Here's to hoping we see some XBee-style 6LoWPAN modules in the near future.

IPv6 Security and those damned dirty NATs

Saturday, February 6, 2010 by darco

With less than 10% of IPv4 addresses remaining unallocated, IPv6 has been getting a lot of attention lately. As such, hardware vendors and ISPs (like Comcast) are now starting to figure out how best to deploy IPv6 connectivity to residential customers.

IPv6 would effectively make the use of IP masquerading (A form of Network Address Translaton used in practically all residential gateway routers) unnecessary. Unfortunately, the current ubiquity of IP masquerading has caused vendors and ISPs to be suspicious of allowing proper end-to-end connectivity to residential customers. I have even heard that some are even considering using the same IP masquerading mechanism for IPv6—for security reasons!

This would be a very bad thing for the future of the IPv6 internet, so I wanted to elaborate on the motivations people have for doing this and ways that it can be avoided altogether.

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m0n0wall now supports IPv6

Friday, December 4, 2009 by darco

I just learned that m0n0wall now supports IPv6, which is great news. Lack of IPv6 support is actually why I stopped using m0n0wall years ago. Since that time I've come to miss it dearly. Now that my only gripe has been addressed, I might consider giving it another try.

In case you are wondering just what m0n0wall is, here is an excerpt from their website:

m0n0wall is a project aimed at creating a complete, embedded firewall software package that, when used together with an embedded PC, provides all the important features of commercial firewall boxes (including ease of use) at a fraction of the price (free software).

If you need a router and have a spare machine, give m0n0wall a try.

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