Older blog entries for elwell (starting at number 94)

DHT22 + Arduino

I recently purchased a DHT22 (Also known as RHT03 on Sparkfun) from Proto-Pic temp and humidity sensor with the aim of using it as an outdoor sensor in the garden. Although there are several DHT22 libraries on github I couldn't get the nethoncho one (or the patched forks) to return anything other than checksum error.

However the combined dht11/22 one I found linked on arduino.cc seems to work just fine. Need to test with -ve temps next but an overnight plot on the bench seems reasonable

Despite many forums saying that it needs 5v I've managed to get it working OK with the 3.3v pin on my nanode, next step is to test on a jeenode and send the output via RF. Oh, and then get a solar panel to run the thing...

Syndicated 2012-05-21 06:32:00 (Updated 2012-05-21 06:33:38) from Elwell

8 Mar 2012 (updated 8 Mar 2012 at 13:09 UTC) »

Prowling round Android

One of the apps I miss from my iphone days is Prowl - This also allowed me to receive IRC messages when away (screen detactched) - Since then I've discovered Notify My Android which does the same thing to android devices, and lo, a quick patch of my script is available

as normal, on github (https://github.com/Elwell/irssi-prowlnotify)

Syndicated 2012-03-08 11:06:00 (Updated 2012-03-08 11:23:46) from Elwell

Yubico / Yubikeys

I'm impressed.

I have small keyring with a USB memory stick, 2 yubikeys and a cofee machine cashless RFID key on. Stupidly I left said key in the vending machine. The system operators at work collected it and set about finding the owner. 1st up, they discovered that they can't read any files off yubikeys (heh) but googled the image and found the manufacturers website and said they had found serial #.... and #.....


Having spend the last 2 days rummaging in car / home looking for it, I got an email from yubico saying that <email> had found my key, based on the serial no of the one I purchased. Work also got an email for the other serial no, which they traced to me.

I'm *very* impressed by this level of attention at yubico, and it means when distributing keys within the business it pays to keep track of the serial no (printed under the 2d barcode).

It does raise the question of how (if) one should notify yubico if they're passed on - especially if I overwrite the yubi profile (as I have done) to prove that I am the rightful owner of the key.

Things to consider with revocation / blocking, especially with a distributed architecture like Fedora....

Syndicated 2012-02-27 19:12:00 (Updated 2012-02-27 19:12:28) from Elwell

24 Feb 2012 (updated 25 Feb 2012 at 19:07 UTC) »

apcupsd via Python to Pachube

In python, the 'default' URL accessing toolkit (urllib2) doesn't support PUT, however I've discovered requests which a) does and b) is in Fedora. So one apt-get install python-requests.noarch and you're off.

So - one trivial script (reusing much of the code for my MQTT variant) you get https://gist.github.com/1903259. The only minor niggle was working out how to prepend the minimum extra json content (version and datastreams) as I'd not used the json libs before.

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