There is some other minor update :
- modprobe.ch has it’s own domain name now (not modprobe.complex.ch subdomain)
- database is clean
- It runs on VAX-11 and I rewrite the CMS in C# o_O

It’s a promise, next post will be interesting.

PS: check it on your smartphone.

Dear reader, have a look at these modest pictures. That’s all we have today.

For the next session I will definitely build a sensor and try to make it work for real. I wish this project could be used in a real situation for awhile.

More photos from Darja are available on flickr :
http://www.flickr.com/photos/55093207@N04/sets/72157625898658468/
http://www.flickr.com/photos/55093207@N04/sets/72157625898504780/

Project 1, Perfusion
Automatic watering for the poor plant. Maybe only mechanically.
Darja is very busy and sometimes she can’t water her plant for days. This is a project to keep the plant in a better shape.

I built a little circuit for a relay on the “high voltage” alternate power from the wall plug (230v).
The purpose of this relay is to switch on and off a pump to water the plant.
The circuit is made so that it fits the arduino shield provided with the homesense kit.
Darja can simply set the output digital pin to switch it.
For the time being, Darja will write a piece of code to turn on the pump a certain number of times everyday.
During our next session, I will build a moisture sensor that will water the plant only when it needs it.

So we decided, all together, that it’s not a good project. And we abandoned it, at least for the moment.

The reasons are the following :
- The matrix isn’t sold anymore
- It’s a lot of code and Darja isn’t very experienced in programming
- It’s a lot of wires for a little home
- It fulfills the fourth rule of the cult of done manifesto

I made a little circuit with an electret microphone and a simple operational amplifier. Something like this.
Darja plugged it in an analog pin, and then… it became more complicated.
Extracting the “noise level” from the sound sample isn’t that simple to understand. The signal wave oscillates between 0 and 5v, around 2.5v. What we want to find is the average of a sample of peaks during a specified amount of time.
Ideally, we would need a standard deviation computation. But we cheat to release a bit of load on the MCU.
To do so we collect 10 values a fast as possible, sort them and calculate the difference between both extremities. That’s all.

The code should be self-explanatory.

#include <string.h>
#include <stdio.h>

int noiseDetectorPin = 0;
signed int noiseLevel;
int ledPins[6] = { 11,10,9,6,5,3 };

int levelMax = 450;
int step;

void setup()
{

  for (int i=0; i<6; i++)
  {
    pinMode(ledPins[i], OUTPUT);
    blink(ledPins[i]);
  }
  Serial.begin(115200);

}

void loop()
{
  noiseLevel = sensor_mean_deviation(noiseDetectorPin);
  step = map(noiseLevel, 0,levelMax, 0,5 );

  Serial.println(step);

  for (int i=0; i < 6; i++)
  {
    analogWrite(ledPins[i], 0);
  }

  for (int i=0; i < step; i++)
  {
    int intensity = 0;
    if (i == step - 1)
    {
      intensity = map(noiseLevel, 0,levelMax, 0,255); // noiseLevel is proportional to levelMax, doesn't matter if it's a fraction or not.
    }
    else
    {
      intensity = 255;
    }
    analogWrite(ledPins[i], intensity);
  }

  blink(13);

}

void print_noise_level()
{
  Serial.print(noiseLevel);
  for (int i = 0; i < noiseLevel/2; i++ )
  {
    Serial.print("#");
  }
  Serial.println();
}

void blink(int led)
{
  digitalWrite(led, HIGH);
  delay(50);
  digitalWrite(led, LOW);
  delay(50);
}

int compare (const void * a, const void * b)
{
  return ( *(int*)a - *(int*)b );
}

int sensor_mean_deviation(int sensor_pin)
{
  int values[10];

  for (int i=0; i<10; i++)
  {
    values[i] = analogRead(sensor_pin);
  }

  qsort (values, 10, sizeof(int), compare);

  return values[9] - values[0];
}

Anyway, we took a little time to discuss what she would like to do, where we should start and which project should be first on the list.
To sort the projects by interest and feasibility, we ranked the following parameters:

time : 1 long <---> short 5
tech : 1 hard <---> easy 5
cost : 1 expensive <---> cheap 5
kit exploitation : 1 null <---> lots 5
interest : 1 null <---> lots 5

Each project’s rank is found by simply adding up the values.

Project 1, Perfusion
Automatic watering for the poor plant. Maybe only mechanically.
Darja is very busy and sometimes she can’t water her plant for days. This is a project to keep the plant in a better shape.
time : 4
tech : 4
dollars : 3
kit exploitation : 4
Darja’s interest : 3
the techies interest : 3
average interest : 3
rank : 18

Project 2, Wall projector
Detecting presence and ambiant light to turn on a wall projection
Darja cannot drill anything in her walls, so she imagined projecting pictures or abstract movements with a pico projector and an old PC.
time : 2
tech : 2
cost : 1
kit exploitation : 1
Darja’s interest : 4
the techies interest : 4
average interest : 4
rank : 10

Project 3, IN->OUT communication (broadcast my life)
Use LED panels to broadcast to the outside events triggered from the inside
Something like : “I’m back home”, “My fridge is empty”, “I’m in this room”, etc.
time : 4
tech : 5
cost : 4
kit exploitation : 5
Darja’s interest : 5
the techies interest : 4
average interest : 22.5

Project 4, yet another alarm clock
Hijack iPhone SleepCycle to turn on a light or a water spray instead of alarm sound
time : 1
tech : 2
cost : 3
kit exploitation : 1
Darja’s interest : 2
the techies interest : 2
average interest : 2
rank : 9

Project 4.5,
Same project than project 4, but detecting the sleep cycle using an arduino instead of SleepCycle application
http://www.crunchgear.com/2008/08/01/arduino-sleep-tracker-diy/
http://www.flyingpudding.com/projects/sleep_tracker/
time : 2
tech : 2
cost : 4
kit exploitation : 3
Darja’s interest : 2
the techies interest : 2
average interest : 2
rank : 13

Project 5, My brain remained in the fridge (RIP)
Detecting every single piece of food in the kitchen, and its amount to automagically suggest recipes based on this information.
time : 1
tech : 1
cost : 1
kit exploitation : 3
Darja’s interest : 3
the techies interest : 3
average interest : 3
rank : 9

Projet 6, Rest In Peace
Noise detector for neighbors,:display current noise level through a vu-meter in the room
time : 5
tech : 5
cost : 5
kit exploitation : 4
interest Darja : 4
interest technik : 4
interests average : 4
rank : 23

The current project, light manipulator
depending on the light intensity, set a servo-motor to turn off the light after a specified delay
time : 5
tech : 5
cost : 5
kit exploitation : 4
interest Darja : 4
interest technik : 4
interests average : 4
rank : 23

The higher the rank, the better the interest/feasibility ratio.
So we first finished the current project, then next time we will start project n° 6.

Our first day was very entertaining and we had great pleasure meeting Georgina and Daniel from Tinkerlondon and Darja, our household.

1. draw two circles that correspond to this thing on a 5mm aluminium plate
2. drill the center with the biggest drill you have (12mm in my case)
3. use a half round ring file to expend the ring to your drawing (a Dremel to speed up)
4. cut the external ring using a jigsaw, goggles and safety gloves
5. reduce the external ring using a sand paper/grinder ribbon
6. paste the ball bearing in you piece of aluminium using a good glue (loctite)
7. insert a long M8 screw in the ball bearing and make is turn on the sand paper ribbon with an angle of 45°. After few turns, the piece should be round enough and well centered.

Punk’s not dead.

Oh yeah… we worked on “la grande fête du centenaire du Musée d’art et d’histoire” of Geneva.
http://www.ville-ge.ch/mah/frs/centenaire/index.html
http://head.hesge.ch/Centenaire-du-Musee-d-art-et-d#IMG/jpg/HEAD_MAH_Borel.jpg

More info on espace-communication and media-design blog on HEAD website.

Many thanks to :
Maud, Alix, David, David, Robin, and all the museum crew.
Raphaelle, Pascal, Victor, Douglass, and all the teacher involved.
Manon, Célia, Carmen, Virginie, Carina, Anh, Sylvianne, Justine, Camille, Paul, Samuele, Alexandre, and all students involved.

Special thanks to Douglass Stanley and David Hodgetts for their support and their code left unused. (I’ll talk more about this later)

Back then, there was a lot of things to do and I didn’t had my electronic stuff on site, so this movie was never made ( Even if it was not a complicated request : triggering a DSLR from an arduino is really easy, there is even different solutions).

Since then, as a regular hackaday reader, I found a post about a minuscule intervalometer for Canon, Nikon and Pentax cameras developed by Achim Sack.

It is just a small connector with only 3 (three) components. It steals the power from the two signal lines of the camera, and set the interval is as complicated as taking two pictures (read the link if you want more details).

I found this design so elegant, minimal, cheap and convenient to use that I decided to build some for all the people doing photography around me.

I didn’t succeeded in making them fit in the connector body (I didn’t got the same connector than Achim) so I have put  heat shrinkable tube around.

It work so well that I had no choice but buy a real DSLR camera

Time to learn what theses aperture and focal things are about… (you can expect better pictures in my future posts!)

So many thanks to Achim Sack for this work, and if somebody is interested for using one, drop me a mail.