Day 2: “Hello Arduino”

After diving into the world of moving electrons on day 1, the second day was dominated by exploring the “heart and soul” of Sketching with Hardware, the Italian-made microcontroller Arduino. With it´s easy to use programm-interface and broad community it is the perfect tool to support the implementation of our project-ideas. After clarifying the basics it was time to play around with sensors, servo-motors, transistors and LEDs. Lessons learned: Nothing is impossible, every idea has the potential to become an interactive reality!

The weekend is reserved to generate ideas for our projects, so now it was time for Sebastian and Hendrik to present the topic: This time the overarching theme is “Outdoor”, which is divided into “Traps”, “Distance” and “Energy Awareness”. Sounds fun!

Day 2

The second day of the Sketching with Hardware course was dominated by the microcontroller “Arduino”. First, the advisor gave us an overview of the open-source project and the community around the Italian microcontroller. After a short introduction to the structure of the “Arduino” with its input and output pins we proceeded to install the required software on our computers. Once this was done we set out to test first simple examples. When all groups had a unit up and running, we could deal with more complex circuits.

Testing the particular examples was very practical. First, the advisors explained the circuits and their subtleties based on schematic drawings then each group could deal independently with the implementation. Input and output possibilities where covered. This included simple circuits with toggle switches which turned on and off an LED or more elaborate designs, which controlled the vibration velocity of a vibration motor with a variable resistor (potentiometer). The emphasis was on digital-read, analog-read and analog-write concepts.
Often, we were free to use any sensor to implement a particular principle which was fun to us and ensured that we understood the concepts and developed creative designs.

Towards the end of the day, the theme of the project week “Bionic” was presented. Some videos were used to further illustrate it. We were asked to gather ideas over the weekend which we would like to develop during next week.

Day 2: Playing Uno!

(No, not the card game.)

The Arduino Board

The possibly most important component in this practical course was introduced on the second day: The arduino uno (and its hard-to-pronounce relatives). We started to get to know our new companion with several basic installments, the first of which was a blinking LED, which is the hardware equivalent to the famous “hello world”. After that, we gradually added more components, like buttons or a potentiometer. Parallel to the physical tinkering, we also learned how to tell the board logically what to do, i. e. the software-side of things.

Input with Sensors

To communicate with the arduino board in other ways than with buttons or the potentionmeter, several sensors proved to be beneficial. We learned about which types of sensors exist and instantly deployed some first experiments with them, e. g. with temperature, distance, magnetic presence or pressure.

Using a pressure sensor

Feedback with Actors

Actors complement the set of hardware utilities and allow the microcontroller to react to the (human) input. Apart from the classical LEDs, we also played around with servos, pushing-cylinders, vibration and an analogue number display. Some of these parts required more power than the arduino itself could offer, so we also learned how to apply transistors to create a basic control circuit. This then allowed us to use an external power supply.

Conclusion

Day number two has brought us valuable understanding of the various input and output methods, and – most importantly – how to apply these sensors and actors to the microcontroller. We also went our first steps with the arduino programming environment. Hopefully, we’re now ready to develop some great ideas to assemble our new hardware equipment and knowledge creatively!

Circuit Diagram

Day 2 starts with some circuit diagram exercises. Every task starts with a sketch of a circuit diagram and has to be translated to a real implementation on a bread board. The following diagrams were made with the fritzing software that can be found at http://fritzing.org

For the first implementation we use a red LED, a resistor, a button, a transistor and a power source. The transistor has three inlets: gate source and drain. The drain and source are connected to the first circuit that also contains the resistor and the LED, the gate inlet is connected to the button. If the button is pressed, the second circuit is closed and the gate inlet of the transistor gets a signal: the LED lights up.

 

With the previous setup the LED stays on as the electric charge can not drain. To avoid that the LED stays on after pressing the button we therefore have to add a pull-down-resistor from the button to the ground.

The second setup uses a IC timer, a LED, a resistor, two capacitors and a potentiometer (containing two variable resistors). The aim of the implementation is to let the LED blink in a frequency that can be regulated with the potentiometer. For the realization we use the LMC 555 SNC IC timer and description of the related datasheet (see “How to read a data sheet” post).

 

How to read a datasheet?

When dealing with electrical components it is important to know their parameters as operating voltage, operating current and so on. Therefore the first step when using a new component, in our case an IC timer, is to look up the corresponding datasheet. Therefore you need to reed the code (numbers or letters) on the component and google it (in our example: “555 SNC datasheet”). Sometimes it is helpful to look also at datasheets from other providers as the datasheets vary and some may provide more details than others.

We used the following datasheet which can be found at http://www.datasheetcatalog.org/datasheet/stmicroelectronics/2182.pdf

IC Timer Datasheet

A datasheet contains all the information you need to use the component. It starts with a general description and the pin connections, a schematic circuit diagram of the component, absolute maximum ratings, operating conditions, electrical characteristics, and application information.

As we wanted to use the component for astable operations we only used the following diagram for the implementation of our application on the bread board:

IC Timer Snapshot Datasheet

Microcontroller and Arduino

What can we say about microcontroller and arduino?

On the second day of our practical course we had a breve introduction about arduino and the language “processing”.

There are many programmable microcontrollers and different languages to program them. For our purpose we use “processing” because it offers many libraries for the arduino controller.

This controller costs about 25 euros. It is also open-source and offers a multi-platform environment which runs on several operating systems.

Our arduino comes with the Atmel AT Mega 328 chip and it is programmable via a USB port. For further information visit the arduino homepage: http://www.arduino.cc

To get used with the new software and hardware component, our first step in the course was to take a LED-light and to work with the blink example. We took a breadboard, a switch, a resistor and of course our arduino connected with the LED-light. The we wrote the blink example and yes: it worked very well!

The next topic was the “analog read”. We used a potentiometer to change the resistors and connected it to our breadboard. After changing our program, we were able to determine the frequency of the blinking.

Our last exercise with arduino on that day was to manage the “simple servo example”. We connected a servo motor to our breadboard and installed the simple servo example from arduino. With that construction, it was possible to control the servo by using the potentiometer.

To understand what we did and to read the information we got during this part of the course, take a look at the slides about microcontroller and arduino:

SWH Slides Part Three