Category Archives: Raspberry Pi
This is a continuation of my last blog post about having my Raspberry Pi log temperatures in my basement.
In the last blog post, I noticed some problems using Node.JS due to some caching issues. Today I found the answer to my problems: Cosm.com.
After some adjustments to my code, I started seeing some pretty cool graphs on Cosm's website.
So this seems like the right thing to use for this.
The modified shell script:
I am trying to have a green thumb. Right now, it is more of a pale yellow with a hint of orange. One thing I thought about doing was a temperature logger for plants that I'm starting and will be transplanted outside in mid-April, after the frost season ends in this area.
I initially thought about using an Arduino, but connecting the Arduino to my network would have required me to buy an Ethernet shield or a Wifi shield, both of which are quite expensive. I happen to have a USB wifi adapter hanging around and a Raspberry Pi that wasn't being used. Match made in heaven!
So the first thing I did was go search around on the Internet and found something from Adafruit that included source code and a hookup diagram for a DHT22 temperature and humidity sensor. Mine is an RHT03, which is similar.
I did find that my RHT03 does not run with 3.3v, so I changed the power rail to 5V, and viola!
The next thing I looked at was the source code. I made one minor change and recompiled - I edited everywhere where I saw temperature in Centigrade and changed it to Fahrenheit.
So the next step was to make it easy to get to. I don't want to log in to my Raspberry Pi via SSH terminal just to check the temperature. So I decided that it seems Node.JS is the way to go because I can very easily write a web server for it.
Nice and simple. And of course, the code:
UPDATE: I've had this running a few days, and realized that it seems Node.js does not like to update as fast as I would like. In fact, it doesn't update until I restart the server... not sure what to do about that, but it drastically limits the usefulness of that tool as a solution in this situation.