Day 4: The building phase begins

The fourth day mainly consisted of building prototypes for the projects. There was no schedule for the day, so each group was free to manage the time on their own.

After the project ideas were set on Monday, for most of the groups the main target for the day was to verify the technical feasability of their ideas. For each project, that meant a different challenge. Mostly, that was to get a working circuit with the intended functionality on the breadboard.

Due to the diverse nature of the projects, a lot of different technologies were explored. From Wi-Fi to Xbee wireless transmitters, GPS, Motors and a lot of different sensors, each group had its own hardware set to tinker with. Even the smell of the laser-cutting machine was noticeable a few times the day.

While building the prototypes, it got obvious that some ideas didn’t work out as expected. Hence, two groups changed their project topics for the sake of better feasability. After all, it seemed to be a successful and funny day for everyone, thanks to Hendrik’s extensive support.

For most of the groups the lab day ended at 5, while some eager groups tortured their Arduinos till 8 in the evening.

Day 4: Ready, steady, go …

9:00: We are finally getting started! Everyone is busily gathering boards, resistors, capacitors and cables, unpacking newly arrived components or hurries away to buy those parts that are still missing. Some groups even seem to plan to integrate unusual components such as umbrellas, inflatable mattresses or small plastic bubbles into their prototypes.

13:00: How to solve  problems, you did not know existed? The more our concepts are progressing, the more challenges have to be faced. Some basic solutions for often occuring problems:

How to connect RGB LED strips?

1. Connect the strip.  You find four wires attached to the copper tabs. In our example (left picture below) we have from left to right:

• white coating: green LED color
• yellow coating: red LED color
• black coating: red LED color
• red:  +12V

Some ready-bought LED-strips already use color coding for the wires: white for the power supply and then red, green and blue wires for the corresponding LED colors.

    

2. Set up the circuit. As our LEDs require more power than the arduino’s build-in power supply can provide, we have to connect an external power source and therefore need to add transistors to our circuit. In the setup used for the GLOW WORM LOVE project (right picture above), three N-channel MOSFETs for each single LED are used, which allows to actuate R, G, and B seperately.

[picture from: http://www.ladyada.net/products/rgbledstrip/ ]

3. Control your LEDs

In the Arduino sketch for every LED, the channels are defined:
void setup () {


pinMode(REDPIN, OUTPUT);
pinMode(GREENPIN, OUTPUT);
pinMode(BLUEPIN, OUTPUT);

}

and can now be assigned seperately to a specific value. For a nice purple we can use

analogWrite(REDPIN, 112);
analogWrite(GREENPIN, 0);
analogWrite(BLUEPIN, 112);

How to convert the sensor output of a LilyPad Temperature Sensor to  °C?

Usually it is sufficient to retrieve the raw values from the LilyPad Temperature Sensor, but sometimes, for example when you are designing user interactions, you would like to know the exact value in degree Celsius. So this is how you do it in your android-sketch:

1. Read the sensor output.
temperature= analogRead(yourInputPin);

2. Convert the achieved value to volt
voltIN = 3300;  //if you connected to 3.3V
voltIN = 5500; //if you connected to 5.5V
float voltOUT = temperature * (3300/1024);

3. Calculate the
factor =  19,8;  //19,8 mV per degree, if you are using a  MCP9701A
factor = 10,0; // 10 mV per degree, if you are using a MCP9700A
float tempC = voltOUT/faktor;




How to switch the direction of a DC motor?

For the blowfish group it is important to have a DC motor capable of switching its running direction. Therefore a circuit with relays is necessary. In fact, two relays are used. One to stop the motor and one to switch the current flow. The basic idea is to use a DPDT (double pole double throw) relay which separates two differently polarized circuits. Without activating the relay, the motor is +/- connected. When voltage is applied to the relay (the switch inside changes its position) the motor gets -/+ connected and runs in the opposite direction.

And some further creative workarounds for so far unknown challenges had to be found.

     

19:00: Time to go home. All five teams have already made substantial progress and the first premature prototypes are moving, blinking andmaking all kinds of nice sounds and less nice noises.

Some impressions:

     

Day 4: This is where it starts

Startup Slideshow

Short one-slide presentations opened the fourth day of the course. Each team had prepared a sketch of their project’s basic concept to show to the others. If you’re interested, you can view them here:

Team 1 | Team 2 | Team 3 | Team 4 | Team 5 | Team 6

Some discussion about what to do first and what could possibly go horribly wrong followed. Luckily enough, it soon became clear that atomic explosions were not to be expected – for now. And that was it with preparation – now let the work begin!

Workshop Workout

The rest of the day we spent working on our circuits, mechanical elements, insanity and so on. Some of us went shopping to get missing parts, some others spread out through the institute’s builduing looking for a drilling machine or whatever vital tool seemed to be severely lacking in existance. Overall, a buzz of creativity sweeped the rooms. It was only broken by (mostly) silent curses, shouted test-activations of audio sensors and the cracking of an old printer being torn apart, salvaging its precious, precious motors. You get the impression.

Resting for now

At the end of the day, several prototypes grew in size, complexity or both. We’re still waiting for that special moment when someone would shout “Eureka!”, but we have already heard a fair share of various non-greek exclamations. A bit worn out, we dropped our soldering irons and laser printers (not literally of course) and let the heat and dust settle in the workshop. Now, to bed, and then: Onwards to the next day!

Let the projects begin!

In medias res – we started!

Since this morning we are actually working on our projects which each team has to complete until Friday, 1 pm.So each team is strongly motivated and very concentrated on their jobs and everyone has a special task which has to be completed after that day.

In the morning, we brought all the electronic stuff we could use to our lecture room, so our work environment looks like a little scrapyard.

Each team started immediately with its work and it seems like everyone has fun and a high interest to reach the personal goal.

Here are some impressions of the work of each team and our atmosphere in which we are progressing our idea of a new communication form.

Team 3 is working with their “ROBOCAT”

Not only electronic components are important, but also raw materials like wood.

The first steps of the new Coffee-meeting-machine

And this will be a new way to coordinate the free time activities.