Monday, March 7, 2011

DIY Wireless Davis Console Interface? Why the Hell Not?

Every now and then I like to go to the Google Dashboard you get when you have a blog on Blogger. The stats tab shows some pretty cool stuff, like page hits per day, which entries are popular, and where the hits are coming from. I saw I was getting some hits from a forum in Holland that I couldn't even read. And apparently, I'm big in Australia.  G'day, mates.

But now that word is spreading on the wonderfullness of hooking up a Davis Weather Station console to a PC for around $15, people are taking the idea and running with it. One of these is a ham radio guy who goes by af4ex on the wxforum site.  af4ex took my idea and did me one better, by using a couple XBee modules to get a connection from his wireless console to his PC... erm, wirelessly.
Look Ma, No Wires (Except for the Four Wires)
Now I'm obviously goofing a bit there.  The XBees are an elegant fit to this design.  The one hooked to the console sports a LVTTL serial port that can connect directly to the Davis expansion port via a breakout board.  The other end has another XBee that is plugged into something called a USB Explorer board, which is just a breakout board with an FTDI based converter like that on the Sparkfun board I discussed way back when.  That gives you a USB interface to your PC.  After programming the XBees from their default 9600 baud to the 19,200 baud used by default on the Davis console, the whole thing just worked.  How cool is that?

af4ex did a great writeup of the design, and you should hit that link ASAP if you are at all interested.  He's put this whole thing together for less than $100, which is a steal compared to what you'd pay for the Davis offering.  But I know what you are thinking: if the PC collecting data goes down for a while, this solution isn't logging the data in the interim.  Would I care, personally?  Not for a second.  Others do, so maybe the Davis logger is a better fit.  But anyone going that route should know that the Davis solution isn't a panacea either.

af4ex has a great design here, but cooler yet would be to get the PC out of the equation totally and hook up to a wireless router like a LinkSys WRT54-G or (better yet) the mighty Asus RT-N16.  Both of these routers have been hacked to death.  Each has a LVTTL serial port available with no extra hardware required.  And each of them runs or can run custom firmware like dd-wrt.  Some custom code on the router and suddenly it is able to serve up web pages with your weather station information on it.  This would rock hard.

Anyhoo, enough rambling.  But before signing off, just a mention that my logic analyzer continues to rot in Customs.  I hope to see it this week sometime, and then it will be time to really dig into the depths of my console once again.

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