Bus Pirate

I have a tracking number now for my Rigol scope, and it is just a matter of time before that bad boy shows up on my doorstep.  To beef up my arsenal, I also have a Bus Pirate on the way.

Another Tool in the Toolbox

This is a neat little board that can be used to spy on serial interfaces like SPI, I2C, etc.  The price is right at $28 plus another $5 or so for the probes.  Shipping is cheap as dirt, but it is out of somewhere in China, so I am looking at anywhere from 10-30 days on delivery.  Hopefully it is less than that.  Once I've got this, I can listen in on what the Atmega in the Davis Weather Station is telling the CC1021 RF chip to do.  Should be interesting to dig into.

I had also wanted to order myself up an Open Workbench Logic Sniffer (OLS), but the boys at Dangerous Prototypes are sold out.  Sparkfun bought up all their stock, and are asking another $20 for it.  While not a ton of cash, it is the principal of the thing.  Think I'll just wait until DP replenishes their stock, which won't be long.

In the meantime, I'm reading Atmel data sheets and looking at CPU emulators, when I'm not researching a replacement for my ancient Radio Shack analog multimeter.  Right now I'm like the Uni-Trend UT71A.  It is 40,000 count resolution, a USB interface, and temperature measurement capability.  I like.  The data logging capability is neutered, but who cares when you have a USB interface?

Scope En-Route!

I'm a little embarrassed to say, but I don't own an oscilloscope.  That changed last night when I pulled the trigger on a Rigol DS1052E from DealExcel.  This scope is a dual channel unit with a 1 GS/sec sample rate, 1 MS of memory, and 50 MHz of analog bandwidth.

But it gets better.

As you can see on this video on Dave Jone's excellent video blog, this scope can be hacked in software to bump its analog bandwidth to 100 MHz.  Since then, there has been a cat and mouse game between Rigol and the hackers to shut this hack down.  The release of Rigol's 2.05 firmware held up for a while, but hackers got the best of it again yesterday.  That, combined with a price of $349 and free EMS shipping, made this an opportunity I couldn't pass up.

I did go back and forth between DealExcel and DealExtreme.What swayed me to DealExcel was:

• they are an authorized Rigol dealer.  Whether this means anything or not if the unit should fail, I don't know.  But it can't hurt.
• they actually have stock.  With DX, you never know whether something is in stock or not, and delays can be very lengthy.

I did read on the eevblog forum that some people were less than thrilled with DealExcel's customer service.  Hopefully I won't need it.  What I am pleased with is that I just ordered the scope last night, and I have a tracking number already this morning.  So I am probably looking at around ten days or so before I get my new toy.

It is about time.

Davis Weather Station Hacking

It is now the Christmas break and I've got a bit of time on my hands.  I have been bugged for some time by the fact that my Davis Vantage Pro 2 Wireless weather station is not very hacker friendly.  Maybe it is time to change that.  It is out of warranty now and I decided to open it up to see what makes this thing tick.

This is the guts of the VP2 Wireless Console.  The controller board is on the left and the display to the right.  The controller board PCB is just double-sided, and contains contact pads for the buttons on the other side.  The bottom part of the unit is where the batteries normally go.  There are just three screws holding the back on and it comes off pretty easily.  One thing you'll want to do before trying this is to put the console into config mode by hitting the Done button and then Down Arrow.  According to the manual, this ensures that the unit isn't trying to write to flash before it loses power.  And it will lose power.  The AC adapter has to be pulled before the back can come off, and the batteries make connection to the main board with just a couple of clips rather than a set of wires.  Losing power is no big deal though: the unit remembers its settings once power is restored again.  Nice.

And no "Warranty Void if Sticker Removed" nonsense either

The first thing I noticed is that the CPU is an Atmel ATMEGA 128L running at 1.8432 MHz.  I was afraid it might have some kind of a custom processor or something to keep power consumption low.  But you don't get more common than an ATMEGA chip, and there are a lot of freely available tools out there that should simplify digging into this.

Oh, you and I are going to get to know each other a lot better soon.

 The second thing I noticed was the radio transceiver chip.  Again, I feared something custom here.  But it turns out that this is a CC1021 from Texas Instruments (data sheet).  TI describes it as a "true single-chip UHF transceiver designed for very low power and very low voltage wireless applications."  Sounds about right.  Hanging off of it is a 833 MHz crystal.  Anywhere I've read about people trying to decode the transmissions from the station were always put off by Davis' "frequency hopping spread spectrum" advertising.  This is much more advanced than the old FSK method they used.  But hey, if you know the transceiver and you know how it is set up, then that opens up some interesting possibilities.

You don't scare me.  I do RF all day at work.

The one thing I don't care about much is the LCD.  It is apparently a custom unit built by Ocular LCD labeled A4144PCB-2.  It doesn't appear on their website (that I could find after 20 seconds of looking anyway).

So the next thing I'm planning to do is order up a Bus Pirate.  This will let me sniff the SPI interface between the Atmega and the transceiver to see how they are configuring it.  While that is in transit, I want to beep out the connection between these two chips, and the connection between the CPU and the expansion interface.  Davis also makes the CPU firmware available, and I might take a shot at building up an emulator so I could figure out how the raw data from the radio gets processed and put out to the interface.  One day it might be possible to

• interface to the VP2 console without buying Davis' crappy Weatherlink software
• build a standalone receiver around a CC1021 and something like an Arduino.  This would give me a low cost receiver with a proper computer interface.

Some pretty cool possibilities here.

PS.  If anybody knows what this is, please leave a comment.

Long time, no blog. But I'm back, and baking.

Like everyone who writes a blog, I have been deficient in keeping it going.  Hopefully I can do a little better going forward.  It is winter now so that has ground the great landscape redesign of 2010 to a halt.  I ended up getting a lot of work done in preparation for next year.  I dug a bunch of holes in some very rocky soil that will give the trees I plan in 2011 a fighting chance.

So I need something to keep busy with and decided that I'd like to try and bake some really good bread.  I ordered 'Tartine Bread' and 'The Bread Baker's Apprentice' from Amazon.  Both books are excellent.  The sourdough bread on top is from the former, the bagel on the bottom is from the latter.

Basic Country Bread from "Tartine Bread"

Bagel from "The Bread Baker's Apprentice"

Both attempts really turned out well and I was very pleased.  I am not a baker at all but I can follow directions.  Hopefully I'll develop more of a feel for it as I do this more.  I'd also like to give a rye bread a try one of these days soon.