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Posts about physical computing

Playtesting Results

Last week Camilla and I did Playtesting with our fellow students. In general the results were positive, with some testers expressing an interest in using the final project. Some of our ideas about how the interaction would work were not as well received as I expected.

Results Summary

One tester told us he had previously discussed our project idea with his wife, who works as a therapist. She thought it would be helpful to have some way to help patients practice breathing exercises before the session begins. I find it encouraging that somebody found our project to be sufficiently intriguing to talk about it with someone else. I know she'll be at the Winter Show and I'm looking forward to showing her the final result.

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Playtesting

Tomorrow we will begin Playtesting for our final project. I'm feeling good about the direction of our project and am looking forward to answering our user interaction questions.

New Design

We made some changes to our design. Most notably, we are going to drop MIDI sounds in favor of sampled sounds in mp3 or wav format. This simplifies our design and also removes the requirement that future users of this device will need to buy relatively expensive MIDI software to make pretty sounds. Additionally, we discovered that there might be some shortcomings in a Mac's MIDI subsystem that may be behind some of the technical challenges we faced during the midterm.

We are going to continue referring to our device as MIDI Meditation until we come up with a better name. The name of the project is probably the least important thing for us to think about right now.

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Final Brainstorming

Camilla and I decided that for our final project we will continue working on our MIDI Meditation device. We did well working together and we have a good project idea. The feedback from the midterm presentation is that if we improve the interaction and user experience we will have a great final project and an intriguing submission for the final show. Rather than try to build some kind of crazy flying robot, I believe that working on the interaction and user experience design will be a good learning experience for me.

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MIDI Meditation

Camilla and I built a MIDI Meditation machine for our midterm project. The device is equipped with a heartbeat sensor to detect when the user's heart beats. It plays a single MIDI note in sync with the heartbeat. The main idea is to help the user become more aware of their heartbeat while meditating and possibly get needed feedback for lowering their heart-rate through meditation.

The interaction is intriguing and stimulated the curiosity of our classmates. Several people gave it a try and enjoyed the experience. I'm not a meditation practitioner but I did give it a try. My heart-rate stayed constant throughout while I became more aware of my heart beating. Hearing the same note play in sync with my heart was surreal.

A photo of the device, taken by Camilla, is below:

/images/itp/pcomp/week7/midi_meditation.jpg

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Heartbeat Detection Study

Purpose of detecting heartbeat data

Our Midi Meditation project is a physical computing device that will repeatedly play a single note in sync with the user's heartbeat. Fundamental to this is the ability to reliably detect when a user's heart is beating.

We want our device to work effectively for most or all people. This means it should play one note in sync with the user's pulse without extra notes between beats.

We had a pulse sensor suitable for an Arduino to use for this project. One approach for prototyping this is to code a heartbeat detection algorithm on an Arduino after viewing the sensor readings on the Serial monitor for a couple of people. This approach could work but would require a lot of parameter tweaking to get it "just right" with repeated user testing between parameter adjustments.

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Midterm Ideas and Serial Communication

This week we began learning about Serial communication. I knew what Serial communication was but never did the programming for it on a micro-controller or at a low level like this. This relates to other things I've done with USB peripherals I am happy to learn more about how it works. In particular, the ability to send and receive Serial messages with Python opens up a whole new world of project ideas for me.

Questions

I have some questions about Serial communication. First, what is the Serial channel doing when it is not sending a message? The voltage on the wire will be interpreted as either high or low. How does it differentiate between the absence of communication and a series of null bytes?

The second question has to do with communication errors. How important is it for the code to be robust to communication errors? How common are they? What are the programming best practices to minimize the impact of errors?

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User Experience and Interactivity

More reading and Physical Computing experiments!

Sketching the User Experience

Sketching the User Experience, by Saul Greenberg and Bill Buxton, is a book about design techniques that are useful for user experience design. The main idea is that sketching is an effective tool for designers to quickly develop, communicate, and record ideas. The book first explains the importance of design techniques, and then goes through a variety tools a designer can use. Some are obvious, like a simple quick sketch, but others are not approaches I would have thought of on my own.

The book is clear that reading about sketching user experience is not the same actually going through the process sketching user experience. To explore this, I went through the book and thought about how I could incorporate this into my behaviors.

I (almost) always have my phone with me, and I have Evernote on my phone. Evernote has some neat features for storing hand drawings that I don’t use very often. I thought it would be a good idea to explore this and see how easily I can use it to sketch a design.

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Experiments With Sound

Upcycling a Speaker

A year ago someone gave me a birthday card that played a song when the card was opened. As I was interested in learning more about circuits, I took apart the card and saved the electrical components for a time when I could dissect them and learn more about how they work. Last week we learned about sound in our physical computing class, so it seemed like a good time to put the inexpensive speaker to good use.

To upcycle the speaker I rewired it to give it red and black wires for the speaker's positive and negative terminals and a header pin to go into a breadboard. I also built a 3D printed case as an assignment for my 3D printing class.

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Input and Output Experiments and Weekly Readings

Electronics Lab

Our assignment for this week was to create something using digital or analog inputs and outputs. The circuit I created will light up a 3-color LED with a new randomly selected color when a button is pressed.

Here is a photo of the completed device:

/images/itp/pcomp/week3/random_color_picker.jpg

And a schematic of the circuit:

/images/itp/pcomp/week3/random_color_picker_bb.jpg

The Arduino uses digital input to detect when the button is pressed and released. It picks random RGB values and outputs analog values to light up the 3 color LED in that color. Observe I am using the 3 resistor values I calibrated for last week's assignment to make the LED's 3 colors balance out.

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First Electronics Lab and Weekly Readings

Electronics Lab

Our assignment was to create something using switches. My goal was to use 3 switches and a 3 color LED to make a circuit that can produce any color.

First I wired a circuit with a 3 color LED, 3 1K Ω resistors, and 3 buttons, like so:

/images/itp/pcomp/week2/three_buttons_equal_resistance.jpg

I am using my Arduino to power the board. Each button can be on or off, so this can produce 8 different colors. In the picture below I am activating the blue and red colors, making magenta.

/images/itp/pcomp/week2/three_buttons_equal_resistance_on.jpg

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