Building openWRT

I have got a little bifferboard single board computer which I intend to use to run pywws to send data from our weather station to the weather underground site on the internet.

The bifferboard comes installed with a very small linux distribution called openWRT.   It has a very small python installed, but no python USB support.

I have struggled a bit to work out how the openWRT package system works - the official wiki is a bit confused about what the current version is called (kamikaze or backfire).  It implies you can add packages by downloading them from svn, but this didn't seem to do anything.
I found a useful forum post here, which seems to be the best set of instructions.
You can do

./scripts/feeds update -a

This downloads the list of packages, but does not do anything else.

To get the buildroot system to compile it for you you need to 'install' it using:

./scripts/feeds install python 
./scripts/feeds install pyusb
You can then do "make menuconfig" and python and pyusb are shown to be compiled as packages "".

'make' actually compiles it.

I'll update this when I work out how to add these to the firmware image...

Personal Weather Station

I have just bought my wife, Sandie a personal weather station from Maplin.  It is a much better one than the simple one that broke recently - it has external humidity as well as temperature, plus wind speed and direction and rain detection.  Most importantly it has a USB connection so we should be able to connect it to an internet weather network so it can appear on our iGoogle home pages.

The maplin version is apparently a re-branded WH1080PC weather station - I chose this one rather than a more modern one because people have managed to get it working with Linux - I want to use a very low power single board computer to interface it, rather than a big PC running Windows.

I have chosen a bifferboard single board computer because it is cheap and has both USB and ethernet connections (I would have liked wireless lan too, but could not find something to do that, so I got the two USB port version of bifferboard, so will have a go at adding a USB wireless network interface card to it later).
My original idea was to use some software called meteoplug because you can buy a bifferboard with that already installed, so I know it would work.  However, when I looked into it, it is a subscription service that is not open source - all I really want to do is obtain data from the weather station and send it to weatherunderground, which can not be that difficult.
Fortunately there is an open source project, pywws, which is compatibly with the WH-1080PC weather station.
I thought it best to get it going on a desktop linux set-up first, then try to get it working on the single board computer.
From my Ubuntu 10.10 laptop I did:

svn checkout http://pywws.googlecode.com/svn/trunk/ pywws

sudo apt-get install python-usb

cd pywws 

python TestWeatherStation.py

Initially this gave an error "IOError: Claim interface failed", so I tried:

sudo python TestWeatherStation.py

Success - a string of numbers, and no errors!

To get rid of the requirement to run the program as root you have to tell 'udev' to give other users permission.
lsusb reports the vendor and product ID of the device (1941 and 8021 respectively), but this is actually reported as a USB missile launcher rather than a weather station.
I added a file called 05-weatherstation.rules to /etc/udev/rules.d, which contained the following line:

SUBSYSTEM=="usb", ATTRS{idVendor}=="1941", ATTRS{idProduct}=="8021", MODE:="0666", GROUP:="usb"

I also added a line to /etc/group to create the 'usb' group, and made myself a member of that group.
Re-started udev with 'sudo service udev restart', and now the test works without being root (note the colon in 'MODE:=' - it is very important!

pywws seems to work suspiciously well - creating a data directory (~/weather/data) and running

pywws/LogData.py -vvv ~/weather/data/

creates a file with some convincing looking numbers in it.   I have created a weather station on weatherunderground, so I think the next thing to do is install the weather station outside, then try to use pywws to send data to weatherunderground.