Sound and Movement | PComp #4

This week in Pcomp we looked into controlling sounds/speakers and servo motors with arduino. The first task in the lab was to control the pitch of a speaker depending on input from a variable resistor. I took the light meter I made last week and after some tweaking installed a speaker on the breadboard to provide an audio indicator along with the succession of lights. The pitch increases as the amount of light hitting the sensor increases. I was very surprised that the addition of the speaker only required a couple lines of code to be functional.

Video: Lightmeter + Audio

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The next task in the audio lab was to have the speaker play a melody. This required a library to be called in the Arduino IDE and the use of some arrays, which I don’t have much experience with. However I followed along with the lab closely and was able to get the melody playing on my arduino. The slight change I made from the lab was to assign different pins because I wanted to keep my light meter operational.

Video: Arduino melody

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And last up for the audio lab was to build an instrument. I had limited success here. I was able to get responsive tones from a few light sensors, however I also had a persistent buzzing tone that I couldn’t eliminate. I realized that part of this may be due to the fact that I am maintaining my light meter on the same board and that I may have unintentionally introduced some interference or error. I plan to attempt this again with a clean breadboard later this week.

Video: Arduino Instrument (Work in progress)


At this point I moved onto the servo lab and ended up successfully including a servo as another responsive element in my light meter.

Video: Arduino light meter + Sound + Servo

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I’ve been having a good time building around this light meter. I realize it’s fairly basic but I find it helpful to work with something thats somewhat familiar and somewhat new at the same time.

Lab + Photometer | PComp #3

The purpose of this lab was to get a sense for how to program analog and digital input/output with an Arduino.

Examples shown to us in class

I started with the digital input example where I was able to get two different colored LEDS to alternate based on a switch button. I realized halfway through that I had switched the LEDs from what was shown in the lab but it was easy enough to change the code and have it work properly either way.

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Video-Aurdino Alternating LEDs

Next I worked on the analog input lab which uses a potentiometer to effect a variable as the analog input and apply a range of power to an LED via the digital output. (a portion of the previous circuit was left on the board).

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Video – Arduino Variable LED


After completing these labs I decided to try to build a sort of photometer with some LEDs and a photosensor. My goal was to illuminate the LEDs in a sequence as the resistance of the photosensor changed. This meant reading an analog input and providing power to a series of LEDs via the digital out. The schematic I drew at the time looked like this:


I started using a potentiometer rather than the light sensor so that I could test the programming for the lights a series of precise levels.  After some trial and error with the programing I had it working roughly the way I wanted it to.

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Video – Arduino Indicator Light Photometer

The LEDs turn on and off in sequence as the resistance changed and when the range was maxed out they all flickered to indicate that it was as high as possible. Lastly I removed the potentiometer and replaced it with a photosensor and a 10 kohm pull down resistor. I recalibrated some of the levels so that the LEDS would generally represent a range of typical room brightness and felt happy with the results.

Video – Arduino Indicator Light Photometer (2)


Observation – POS system at The Container store | Pcomp #3


Pick a piece of interactive technology in public, used by multiple people. Write down your assumptions as to how it’s used, and describe the context in which it’s being used. Watch people use it, preferably without them knowing they’re being observed. Take notes on how they use it, what they do differently, what appear to be the difficulties, what appear to be the easiest parts. Record what takes the longest, what takes the least amount of time, and how long the whole transaction takes. Consider how the readings from Norman and Crawford reflect on what you see.


Customers wait in a line to enter a bank of registers. When a cashier is done with their previous customer they call another over (sometimes this requires raised voices and repetition). Once the customer arrives at the cashiers POS they ask the customer if they have a rewards card – most don’t and don’t want one. The costumer then begins to pile mostly large plastic containers onto the counter top as the cashier scans the barcodes with a scanner gun. Each item pops up onto the display facing the cashier and occasionally they require some form of verification or confirmation (I assume this is in the case of sales or other special circumstances). Throughout this process the cashier has to stop scanning and rearrange some of the items and bag them. Once they are done scanning they focus on bagging and let the customer know they can pay. This is the trickiest part because the variety of payment options require varying levels of interaction on both their part and the customers at the same time that the cashier is trying to bag up all of the purchased products (due to the complex and large items this is a more complicated and less repetitive task than at most retailers). Eventually all the products are bagged up and payment has been made.

Some of the cashiers vary this process by being more vocal than others – I saw one of the cashiers asking ahead of time how the customer intended to pay while others waited. Some of them would prepare bags or boxes ahead of time while others just waited between customers.

It makes sense that some of the cashiers started asking these kinds of questions (they may be told to) since a lot of time and attention is lost when things like the amount of bags you want, whether you have a rewards card, and how you intend to pay all effect the speed at which the cashier can check out customers. having to bag the products while transacting the purchases seems to make both tasks less efficient. It was clear that the easiest part of the interaction and the portion of the process that seems to be done with the most confidence is the scanning and product information retrieval.

Based on the readings from Norman and Crawford, on the whole I’d say the POS system is a good design for very general use. The method of inputing information, taps on the screen and the scanner gun, work quickly, accurately and are well suited for the task. The POS system is able to associate the barcodes with a large product database and tabulate the totals with discounts and other modifications. The machine is also fairly good at making its output clear and useful using the tough screen and the payment terminal. However, there is often confusion about when to swipe a credit card and the cashier has to do a lot of verification and reading off the screen to the customer which seems like it could be improved. In addition, these kinds of POS systems are fairly standard so most customers and employees have an idea of what to expect and how to use it. Customers know where to swipe and whether or not the payment went through and most of the points of friction seem related to additional programs the store has imposed such as the rewards card. That being said I think there is a lot of room for improvement, particularly before the customers reach the machines themselves. I think that If customers were sorted before reaching the register cashiers would be able to check people out faster and the interaction with the POS system would be more predictable and intuitive for both the customer and employee. As the customers are online they should be asked if they have a rewards card and what method of payment they intend to use. In addition customers with complaints, pricing questions, and other miscellaneous issues should be sorted out of line so that they don’t have to conduct their non-checkout business with a person and platform that are tailored for checkout. Lastly the kiosks that the POS systems sit on should be rearranged so that a dedicated employee can bag things up while the checkout is happening separately. Basically I think the POS system is very good at checking people out but it is not quite so good when this activity is coupled with bagging and sorting out customer issues.


First Circuits | PComp #2

This week I did my first work with circuits by reviewing our class work and the labs available on the PComp website.


I started with a simple circuit powered off of the Arduino containing a 220 ohm resistor, an LED, some little wires, and a button that came with my Arduino starter kit.


The next challenge was to add a couple more LED, first in series and then in parallel to get a sense for how voltage and current change when more components are added.

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As expected when the three LEDs were arranged in series behind the resistor, none of them lit up when power was connected because the voltage that each was receiving was divided amongst the three and failed to reach the level necessary. When I rearranged them into parallel each of them lit up because the voltage was now high enough since the current is what is divided when the components are arranged in parallel.

Next I soldered and attached a Potentiometer to vary the brightness of the LEDs.


This worked surprisingly well and I had way too much fun dimming a single LED on and off.

Lastly I set out to develop a switch myself to use with this board. I decided I’d like to make a switch that reacts to wind and the process turned out to be fairly simple. I attached a couple of wires to the board ahead of my resistor and LED (roughly where the button had been) and put some aluminum foil on the ends of each of them. When the two leaves of aluminum foil touch it completes the circuit and turns on the LED. I mounted this contraption above my A/C and was eventually able to get the switch to activate the circuit as the air blows and to turn off when it doesn’t.



Response to Crawford, Victor, and class discussion | PComp #1

I’m not sure how exactly I would have defined interaction prior to our first class and its related assignments, but I’m fairly certain that at this point coming up with a definition is more difficult. I like the Crawford definition, requiring two actors and a cyclical listening/thinking/speaking process, but as Crawford admits (and demonstrates) that framework can be rather squishy. The idea that the “refrigerator door game” can be disqualified as an interaction for being “beneath the intellectual dignity of almost everybody” is funny but also distracting for me. I couldn’t help but think about how disappointed I’d be to open a fridge with a burnt out light bulb, and whether that is a reflection of my intellect. But Victor’s rant made me feel a little better. He noted the feedback a glass of water provides to it’s drinker via weight, and few pursuits are more intellectual than deciding whether a glass is half empty or half full. Though I’m still unclear on whether this glass or the process of using it is a tool, interaction or both. At this point I’m leaning towards interaction as a spectrum that is much more fluid than Crawford’s system of zero, low and high. As for an original  definition I’d say: Interaction is a relationship formed in pursuit of a goal. So to me Crawford’s refrigerator light and Victor’s glass of water are both good examples of successful interaction despite their simplicity. 


Crawford, The Art of Interactive Design, chapters 1 and 2

Victor’s rant (