And if this works well, I might scale things up a bit for next season’s greenhouse project. It would save me some electronics in pumps and stuff to water the vegetables and fruits. Homegrown.org has a nice idea to upscale this (voila: http://homegrown.org/blog/2010/06/homegrown-how-to-cards-how-to-make-a-self-watering-planter/) , as do many other sites if you google “diy sub irrigation planter” or “self watering container”

A quick picture of one of the bottle:

ps: in the background you see the sort-of-greenhouse and vegetable box… isn’t it amazing to see how everything sprung to life?!

I have spent several nights already trying to get two Arduino boards, each equipped with an Xbee-shield, to communicate. I worked on the example provided on the Arduino site, but no luck It turned out that I obtained two shields with “Series 2″ radio’s, which meant the example code would not work right off the bat. But, a post on Didier Stevens’ website pointed me in the right direction and eventually I was able to get both boards running and communicating.

The two boards seem to be communicating as one is sending the signal to switch an LED on and off every second on the other board. I see the LED switching on and off, but the behaviour is quite erratic. So, more investigation to be done there…

To be continued…

If you want to follow the prototype on twitter, follow @ProjectG3H

There are some issues with the temperature readings as they spike to impossible levels every now and then. I will have to get into that later. But, for now the prototype is able to get environment data and connect to the internet to tell the world about them. And it was not a very hard thing to do. Very exciting!

I will do a thorough write-up later to share as much info as possible, but for now I am just so excited that this is actually sort of working, that I had to share!

Below is a little preview of the sensor data that is sent to pachube!

Temperature (in Celcius):

Light (value from the LDR):

Soil moisture level:

The grid structure is based on the square foot gardening method, by Mel Bartholomew. Since I do not have a huge garden to grow vegetables, I heard about square foot gardening and decided to give that a try.

I bought this book to get to know a bit about it:

And with the box ready to go, it was time to plant the first seeds. Actually, I made two boxes: one in the open air, one for use as a small green house.

And so we ended up with two boxes filled with different kinds of vegetables and some fruit: brocolli, cauliflower, carrots, lettuce, rocket salad, onions, radish, beets, tomato’s, two different types of strawberry, red peppers and bell peppers. And for fun, we also put some seeds in a propagator: cucumber, melon, aubergine and some beans.

The G3H project electronics, will focus on the greenhouse first. The idea is to monitor conditions in the greenhouse, such as temperature, soil moisture levels, amount of light. And with the information, eventually control a watering system as well as opening and closing doors. A sensor unit in or on the greenhouse will wirelessly transit sensor readings to a receiver in the house which will publish data online. Services like twitter and pachube come to mind

I have ordered additional (arduino) hardware and started work on a prototype. Also, a sensor tube to use inside the greenhouse is in the making. More about that later

I also showed how to get a voltage reading instead of just a number. Today, I post a link to an article that accompanies Oomlout’s ARDX kit, about how to get an actual temperature from a temperature sensor.

Of course I could repeat all they say here and claim its my own, but as I learned it from using my ARDX kit, it is logical to point you to the source: http://www.oomlout.com/a/products/ardx/circ-10

Enjoy!

If you measure the voltage on the pin, you will find that it is anywhere between 0V and 5V, where 0V corresponds to the digital value 0 and 5V corresponds to 1024. This is not entirely true as the minimum voltage is 0.005V, or 5 millivolts.

That means that each step up, measured digitally (the range between 0 and 1024) corresponds to 5V/1024 steps = 0.0048828125V.

This can be easily put into a short function you can use for all sensors using a digital pin:

/*
* getVoltage() – return the voltage on the analoge input defined by pin
*
*/
float getVoltage(int pin) {
return (analogRead(pin) * .004882813);
// reading a digital pin returns a value between 0 and 1024, which corresponds to a voltage range
// between 0V and 5V.
// So, one digital step means 5V/1024 = ~0.005V, or about 5 millivolt
}

With this value it is a lot easier to translate the value read from the sensor to meaningful data. In a future post I will show you how to use a thermistor to measure temperature and use this information to translate the voltage on the digital pin to degrees centrigrade or fahrenheit.

This is the bottom of the greenhouse box with weedcloth attached

The top half of the greenhouse is the glass part, which is not actually glass, but some sort of double sided transparent plastic. The whole frame is aluminium. As you have probably guessed: this was bought, not made by me

After finishing the box and reinforcements to the bottom, it was getting too dark to snap a decent photo, so that will have to wait for later. But I will finish this post with an image of the top half:

And in learning both fields more or less simultaneously, I came up with an idea after reading Make Magazine 18. In that issue, a project is described that uses an arduino to monitor plants and water them automatically, as well as switch on growlights when the plants did not get enough light during the day.

Combined with some stuff I read on square foot gardening and a good offer on a small greenhouse I came up with the idea to build a small, soft of, square foot garden, add a greenhouse on top and control the whole thing with an arduino.

My brother-in-law heard about it on twitter (I am @ArnoJansen, though part of my tweets are in dutch) and called in a “Willy Wortel” invention. Willy Wortel is dutch for Gyro Gearloose, hence the working title for this project: Gyro Gearhead GreenHouse, or G3H in short.

I am currently building the garden box and the greenhouse and have started on setting up a prototype board with the arduino to measure light, temperature and soil humidity. I did take some pictures which I will share later.

For now, let me show you the sensor testcode as I currently have it in my Arduino IDE (it assumes the same setup as the garduino article in Make Magazine, although you may want to change pin-outs):

// Project: G3H Sensor Testcode
// Author: Garduino project, Make Magazine 18 / Modified by Arno Jansen
// Version: 0.1
// Date: April 7, 2010

//include the datetime library, so our garduino can keep track of how long the lights are on
#include <DateTime.h>

//define analog inputs to which we have connected our sensors
int moistureSensor = 0;
int lightSensor = 1;
int tempSensor = 2;

//define digital outputs to which we have connecte our relays (water and light) and LED (temperature)
int waterPump = 7;
int lightSwitch = 8;
int tempLed = 2;

//define variables to store moisture, light, and temperature values
int moisture_val;
int light_val;
int temp_val;

//decide how many hours of light your plants should get daily
float hours_light_daily_desired = 14;

//calculate desired hours of light total and supplemental daily based on above values
float proportion_to_light = hours_light_daily_desired / 24;
float seconds_light = 0;
float proportion_lit;

//setup a variable to store seconds since arduino switched on
float start_time;
float seconds_elapsed;
float seconds_elapsed_total;
float seconds_for_this_cycle;

void setup() {
//open serial port
Serial.begin(9600);
//set the water, light, and temperature pins as outputs that are turned off
pinMode (waterPump, OUTPUT);
pinMode (lightSwitch, OUTPUT);
pinMode (tempLed, OUTPUT);
digitalWrite (waterPump, LOW);
digitalWrite (lightSwitch, LOW);
digitalWrite (tempLed, LOW);

//establish start time
start_time = DateTime.now();
seconds_elapsed_total = 0;

}
void loop() {
// read the value from the moisture-sensing probes, print it to screen, and wait a second
moisture_val = analogRead(moistureSensor);
Serial.print(”moisture sensor reads “);
Serial.println( moisture_val );
//delay(1000);
// read the value from the photosensor, print it to screen, and wait a second
light_val = analogRead(lightSensor);
Serial.print(”light sensor reads “);
Serial.println( light_val );
//delay(1000);
// read the value from the temperature sensor, print it to screen, and wait a second
temp_val = analogRead(tempSensor);
Serial.print(”temp sensor reads “);
Serial.println( temp_val );
//delay(1000);
Serial.print(”seconds total = “);
Serial.println( seconds_elapsed_total );
//delay(1000);
Serial.print(”seconds lit = “);
Serial.println( seconds_light);
//delay(1000);
Serial.print(”proportion desired = “);
Serial.println( proportion_to_light);
//delay(1000);
Serial.print(”proportion achieved = “);
Serial.println( proportion_lit);
Serial.println();
Serial.println();
Serial.println();
Serial.println();
Serial.println();
Serial.println();
Serial.println();
Serial.println();
delay(1000);
//turn water on when soil is dry, and delay until soil is wet
//if (moisture_val < 850)
//{
//digitalWrite(waterPump, HIGH);
//}

//while (moisture_val < 850)
//{
//delay(10000);
//}

//digitalWrite(waterPump, LOW);

//update time, and increment seconds_light if the lights are on
seconds_for_this_cycle = DateTime.now() – seconds_elapsed_total;
seconds_elapsed_total = DateTime.now() – start_time;
if (light_val > 900)
{
seconds_light = seconds_light + seconds_for_this_cycle;
}

//cloudy days that get sunny again: turn lights back off if light_val exceeds 900. this works b/c the supplemental lights aren’t as bright as the sun:)
//if (light_val > 900)
//{
//digitalWrite (lightSwitch, LOW);
//}

//turn off lights if proportion_lit>proportion_to_light, and then wait 5 minutes
//if (proportion_lit > proportion_to_light)
//{
//digitalWrite (lightSwitch, LOW);
//delay (300000);
//}

//figure out what proportion of time lights have been on
//proportion_lit = seconds_light/seconds_elapsed_total;

//turn lights on if light_val is less than 900 and plants have light for less than desired proportion of time, then wait 10 seconds
//if (light_val < 900 and proportion_lit < proportion_to_light)
//{
//digitalWrite(lightSwitch, HIGH);
//delay(10000);
//}

//turn on temp alarm light if temp_val is less than 850 (approximately 50 degrees Fahrenheit)
if (temp_val < 850)
{
digitalWrite(tempLed, HIGH);
}
}

/
Project: G3H Sensor Testcode

// Author: Garduino project, Make Magazine 18 / Modified by Arno Jansen

// Version: 0.1

// Date: April 7, 2010

//include the datetime library, so our garduino can keep track of how long the lights are on

#include <DateTime.h>

//define analog inputs to which we have connected our sensors

int moistureSensor = 0;

int lightSensor = 1;

int tempSensor = 2;

//define digital outputs to which we have connecte our relays (water and light) and LED (temperature)

int waterPump = 7;

int lightSwitch = 8;

int tempLed = 2;

//define variables to store moisture, light, and temperature values

int moisture_val;

int light_val;

int temp_val;

//decide how many hours of light your plants should get daily

float hours_light_daily_desired = 14;

//calculate desired hours of light total and supplemental daily based on above values

float proportion_to_light = hours_light_daily_desired / 24;

float seconds_light = 0;

float proportion_lit;

//setup a variable to store seconds since arduino switched on

float start_time;

float seconds_elapsed;

float seconds_elapsed_total;

float seconds_for_this_cycle;

void setup() {

//open serial port

Serial.begin(9600);

//set the water, light, and temperature pins as outputs that are turned off

pinMode (waterPump, OUTPUT);

pinMode (lightSwitch, OUTPUT);

pinMode (tempLed, OUTPUT);

digitalWrite (waterPump, LOW);

digitalWrite (lightSwitch, LOW);

digitalWrite (tempLed, LOW);

//establish start time

start_time = DateTime.now();

seconds_elapsed_total = 0;

}

void loop() {

// read the value from the moisture-sensing probes, print it to screen, and wait a second

moisture_val = analogRead(moistureSensor);

Serial.print(”moisture sensor reads “);

Serial.println( moisture_val );

//delay(1000);

// read the value from the photosensor, print it to screen, and wait a second

light_val = analogRead(lightSensor);

Serial.print(”light sensor reads “);

Serial.println( light_val );

//delay(1000);

// read the value from the temperature sensor, print it to screen, and wait a second

temp_val = analogRead(tempSensor);

Serial.print(”temp sensor reads “);

Serial.println( temp_val );

//delay(1000);

Serial.print(”seconds total = “);

Serial.println( seconds_elapsed_total );

//delay(1000);

Serial.print(”seconds lit = “);

Serial.println( seconds_light);

//delay(1000);

Serial.print(”proportion desired = “);

Serial.println( proportion_to_light);

//delay(1000);

Serial.print(”proportion achieved = “);

Serial.println( proportion_lit);

Serial.println();

Serial.println();

Serial.println();

Serial.println();

Serial.println();

Serial.println();

Serial.println();

Serial.println();

delay(1000);

//turn water on when soil is dry, and delay until soil is wet

//if (moisture_val < 850)

//{

//digitalWrite(waterPump, HIGH);

//}

//while (moisture_val < 850)

//{

//delay(10000);

//}

//digitalWrite(waterPump, LOW);

//update time, and increment seconds_light if the lights are on

seconds_for_this_cycle = DateTime.now() – seconds_elapsed_total;

seconds_elapsed_total = DateTime.now() – start_time;

if (light_val > 900)

{

seconds_light = seconds_light + seconds_for_this_cycle;

}

//cloudy days that get sunny again: turn lights back off if light_val exceeds 900. this works b/c the supplemental lights aren’t as bright as the sun:)

//if (light_val > 900)

//{

//digitalWrite (lightSwitch, LOW);

//}

//turn off lights if proportion_lit>proportion_to_light, and then wait 5 minutes

//if (proportion_lit > proportion_to_light)

//{

//digitalWrite (lightSwitch, LOW);

//delay (300000);

//}

//figure out what proportion of time lights have been on

//proportion_lit = seconds_light/seconds_elapsed_total;

//turn lights on if light_val is less than 900 and plants have light for less than desired proportion of time, then wait 10 seconds

//if (light_val < 900 and proportion_lit < proportion_to_light)

//{

//digitalWrite(lightSwitch, HIGH);

//delay(10000);

//}

//turn on temp alarm light if temp_val is less than 850 (approximately 50 degrees Fahrenheit)

if (temp_val < 850)

{

digitalWrite(tempLed, HIGH);

}

}

To start the new year well in the tinkering department, I bought an Arduino! What’s that, you ask? Well, the Arduino website explains it thusly:

Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.

Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino programming languageWiring) and the Arduino development environment (based on Processing). Arduino projects can be stand-alone or they can communicate with software on running on a computer (e.g. Flash, Processing, MaxMSP).

Arduino Duemilanove board

It has been around for a few years now, and I have always had an interest in programming microprocessors to allow devices, contraptions, etc to be functional independent of a PC. With Arduino, interfacing with the outside world is easier than ever which convinced me I should give it a try.

Since I live in the Netherlands, I looked for a resource in my country that provided Arduino’s. After looking through the list of suppliers in the Netherlands, I ended up buying from Floris.CC and ordere the “Arduino Experimentation Kit“, made by Oomlout and ordered from Floris.cc

Since receiving it, I played around with the thing a bit and what struck me most is the ease with which you can build contraptions that sense and act on their environment. In the next few weeks I will do a write up on the ARDX kit itself.

Playing (becaues that really is what it is!) with the Arduino is so much fun that it instantly sparks many creative ideas that this thing can help with. As those ideas are developed, I will do write-ups here to share the knowledge I gain.

If you want to know more about Arduino, get started with this PDFCast from Make Magazine, or watch these “Arduino 101″ video’s on YouTube.

Arduino Logo

See here the progress after only 4 days:

That was on March 2, and look at the progress two days after that:

This looks very promising. Some of the earth is already being pushed out by the developing roots of the seeds, so I will have to put them in a larger pot this weekend. It is beautiful to see the seed-shells still hanging on one of the leaves. Beautiful to see these germinate and grow so fast! It is also evident, one of the six pots is not doing anything.

Unfortunately, the herb-kit and the lavender have not shown any progress yet