Light!

That wonderful stream of photons that drives photosynthesis inside the chloroplasts. Our little $0.95 photocells preformed great in their first test. In the dark of a closet they measured 500,000 Ohms and outside in the mid afternoon sun they measured 50 Ohms, a 4 log range! Very exciting.

It is reading from about 550nm to 650nm light (green-yellow range) which is what our eyes see the best. The plants however will prefer more blue (400nm-550nm) and red (650nm-700nm) which is hopefully what the LED lights will provide. But these sensors do a good job of reporting the relative intensity of the light and thats all we need from them!

In the future they will be used to monitor light levels inside the greenhouse chamber and potentially turn on the supplemental LED lights on cloudy or rainy days.

Closet: 500,000 ohms
Indoors, natural light: 1000 ohms
Indoors lights on: 1000-400 ohms
In front of an LED flashlight: 300 ohms
Outside in the midday sun: 50 ohms

It is however, an analog device. So we need an ADC to convert the signal so that the digital Pi can read it. Or we upgrade to the most expensive digital lux sensor that is more accurate and precise but about 10x more expensive. It also has a much wider range of light it can see; from visible all the way to IR.


Cheap analog sensor:
http://www.adafruit.com/products/161#Description

More expensive digital sensor:
http://www.adafruit.com/products/439

Some simple numbers.

Here's a simple python app to show integers versus floats.

I'm Alive! Follow me on twitter!

Using the Twitter API tweepy I can now tweet from the command line. I also learned how to tweet my processor temperature.

Tweeting will be crucial in the future as we plan to use Twitter for status updates on the hydroponics.

Follow me on Twitter!  @rpiph1 

Most of the credit goes to: Orer2ddo456 whose tutorial can be found here...

http://c-mobberley.com/wordpress/index.php/2013/04/26/raspberry-pi-connect-to-twitter-account-using-tweepy-installation-and-tweet-cpu-temperature-example/

Code to follow...

Hello World!

This blog will chronicle my attempts to get a raspberry pi to control and monitor a simple hydroponic set up. Living in an urban setting and still wanting to do a small amount of "farming" hydroponics offers the most efficient use of space/nutrients that won't slow down when it gets cold out! The idea is to do this as cheaply as possible with easily source-able and replaceable parts. The whole set up will be designed to sit inside by a window and have a footprint of ~ 2ft wide x 6ft long x 4ft high. It will hopefully also be able to tweet updates about the system on a regular basis for monitoring purposes.

The Pi will potentially monitor:
-water temp
-water level of the hydroponic reservoir
-light levels in the room
-air temp/humidity both inside and outside the greenhouse portion

This blog will have:
-pictures of the design as I work through it
-parts bought to build the green house and hydroponic parts
-part numbers of electronic monitoring components
-all the python code as it is developed

Here is some resources I have collected as I have begun to think about this problem:

PiPlanter:

http://www.esologic.com/?p=665

Adafruit:

http://www.adafruit.com/products/801

Phidgets- lots of sensors:

http://www.phidgets.com/products.php?category=36&product_id=3550_0

OpenSource environ control:

http://sourceforge.net/projects/envirocontrol/

Atlas pH:

http://atlas-scientific.com/product_pages/embedded/ph.html

ET boxes:

http://www.greenfortune.com/streamgarden.php

GPIO:

http://code.google.com/p/raspberry-gpio-python/wiki/BasicUsage

Temp and Humidity Sensor:

http://www.rpiblog.com/2012/11/interfacing-temperature-and-humidity.html

Tweepy tutorial

http://c-mobberley.com/wordpress/index.php/2013/04/26/raspberry-pi-connect-to-twitter-account-using-tweepy-installation-and-tweet-cpu-temperature-example/

Tweepy home explanations

http://pythonhosted.org/tweepy/html/index.html