A miner’s canary(‘s) cage

The gas sensors and stepper door control are now together, sensing high levels of Carbon Monoxide or Methane will open the bird cage door (See previous post). I put in a small push button to act as a test switch- like on smoke detectors. I don’t think it is quite ready for a bird just yet. Need to take it off the breadboard and put it onto something more permanent and clean up the wires. Thought it would also be good to put clear acrylic behind the electronic components- so the canary can’t attack the exposed parts.

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Canary in a Coal Mine: In two parts

I am taking a miniature break from my Sims Needs Meter, to make a carbon monoxide and methane gas sensor unit for a canary cage.

Today it is in two parts, hoping to put them together tomorrow. First part is the arduino powered cage door:

Above is a unipolar stepper being driven by a darlington array. I am just using the stepper example in the arduino ide. There are a few different versions- one step, full rotation etc. Arduino reference for wiring a stepper. The stepper has a small robot wheel attached to it’s shaft- which i have glue some fishing line to. The groove in the wheel is designed to fit a small rubber tire into it- but here it is perfect for the fishing wire to be wound up onto it. And that is about it. Super simple. Now to find a way to attached it to the bird cage that does not involve gaffa tape.

And the second part is the:  Carbon Monoxide (Top) and Methane (Bottom) sensors:

These sensors are soldered to the sparkfun gas sensor breakout boards, and using a simple analog read to extract data. There are very limited tutorials available for gas sensors, unless you are making a breathalyser or fart-meter. So after I put these two parts together, I will attempt to create a comprehensive tutorial. Still searching for some more info on calibration and interpreting the readings.

Black Box

This is my Black Box. It is an art object that tracks and stores information about its environment. It does noting with the collected data except remember it, continually accumulating information about its own existence. The fours lines are time in existence, the distance in has travelled, current position and relative percentage to current position and an overall interactions count.

I have written a few post about the making of this box. Part One //  Part Two . And there is likely to be more. I am going to be working on some upgrades for this including:

• charging circuit
• low power state for shipping
• Longitude/latitude configuration into regions
• memory recall- randomly recalls previous states. ie “day 34 in Brisbane, 34890 interactions”
• randomly removing or “forgetting” data

After its next set of updates I would like to start shipping it around the world. If you would like to offer the Blackbox a place to stay for a couple of days, please contact me.

Black Box: On the tram

I have hook up my GPS module to my Black box prototype.  For this I wanted to calculate the distance travelled. So I am using a gps distance calculation example, which calculates the distance between two longitude/latitude points. Code only had to be modified slightly to update the waypoint to be measured against and accumulate the total distance travelled. I took it for a tram ride. It works… As it calculates the distance between waypoints, it is more accurate the more often it updates. This code below is programmed to update every 1/4 of a sec, but mine does not get close to that. 1-5minutes seems standard. I will have to look into how to get steadier updates.

GPS distance pde

So currently it is using the four lines on the LCD to display- Time in existence, kilometres travelled, percent of the time it has been in a certain position and an interactions count. I have been working on storing these variables and data logging all collected info to SD. It took a while to get it’s memory working. Writing to SD was simple. But reading this info back and turning into meaningful data was a bit more complex (well for me it was). You need read the data back into a string and then convert string to a char array turn the array into a float/long etc… or maybe you could just read the info back into a char array. hmmm.

My new favourite friends are:

atol  and atof

example:
long stringToLong(String s)
{
char arr[12];
s.toCharArray(arr, sizeof(arr));
return atol(arr);
}

The box is looking a bit worse for wear, but I wired up a shield for everything yesterday. So it is good to go. Will be making the actual box next week.

Blackbox: Part I

This is my first test of my “black box” work. I have been fond of the idea for a while of an art object that tracks and stores information about its environment. It does noting with the collected data except remember it, accumulating information about its own existence. So to do this I will be interfacing a few different sensors (GPS, accelerometer,) and putting these in a small black box with a LCD screen to display its collected data. The cardboard box is just temporary until i make the real one.

My next few posts will be the progressions of this work. I have started by testing the accelerometer. For this i have only needed to use 2-axis. At the moment it is set to display which way it is positioned. (right way up, upside down, left side up etc etc) the percentage shown is relative to how often it is in the current position compared to the other positions. So in the picture above it has been upside down for 50% of the time.

ADXL335

Testing out my new 3-axis accelerometer by Sparkfun (ADXL335) . Almost too easy to wire to the arduino. Functional first time. Now just to interpret the data…

Tutorial: http://www.arduino.cc/en/Tutorial/ADXL3xx

Locosys LS20031 GPS module

Acquired a Locosys LS20031 GPS module. This will eventually be put together with the accelerometer, Piezo, thermistor and any other sensors i have lying around for my Black box project- will post project soon.

Tutorial: http://www.sparkfun.com/tutorials/176

Arduino Sketch: gps_parsing_v13.pde (Remember to change the baud rate)

TinyGPS library: TinyGPS10.zip from http://arduiniana.org/libraries/tinygps/

Piezo element

The piezo can detect knocks or vibrations. Also can be used as buzzer.

Tutorial: http://www.arduino.cc/en/Tutorial/Knock