Monthly Archives: March 2013

Look & Feel

For now I need to run a bash script to initialise the pin that drives the buzzer after reboot, then I can drive the buzzer by sending a HIGH command to the pin.

So while I iron out my script to correctly drive the buzzer, I thought I’d share a pic of what my setup currently looks like.
It’s still a work in progress, using a breadboard so it’s not pretty but still worth sharing 😉

2013-03-23_Pi_Setup (Large)

Temperature & Humidity Sensor

I’ve finally gone round to properly connecting my DHT22 sensor to my Raspberry Pi.
It’s actually been working fine for about 2 week, but as it was sitting on the breadboard on top of the Pi, the readings were not exactly accurate: it’s pretty warm and dry up there.
So today I moved the sensor outside to get real readings.

I’ve based my setup thanks to a tutorial on Adafruit. You can get it HERE

I’ve done a few changes though:

  • Based on the temperature and relative humidity readings, I’m calculating the dew point / frost point. The formula I used is this one:

    Dew point equation

    Dew point equation – Click for source website

  • I’m updating the readings to my SQL Database so I can use then on any page.
  • I’ve set up the readings to get added to an online Google spreadsheet only once per hour. The idea is to keep recording for as long as I can and then get some yearly trends. You can access the spreadsheet HERE

Bash is dead, long live Python

I’ve started a major update of my main script.
Until now I was using bash to control the GPIO of the Raspberry Pi, but it was just too slow and was using too much CPU resources.
So today I’ve transcripted everything from Bash to Python using the functions from

Well I say everything, I’m only missing the piezo buzzer controller as the functions above do not yet include PWM which is needed to drive the buzzer.
I’ll see if there is a way round until this function becomes available.

Watch this space…

Mobile View

I’ve added today a plugin to the site to allow quicker / better viewing when using mobile browsers.
For those of you who use WordPress and are interested in knowing, the plugin I use is WordPress Mobile Pack