Lab: Comination Combo Lock & Luv Meter

I decided to combine these assignment, both as a challange and as a time saving device. What I came up with was a device with two photoells and two led's; the led's would switch from 'not' to 'hot' only when a certain (but different) range was returned on both photocells at the same time.

The code looks like this:

#define analogPin1 0 //photocell 1
#define analogPin2 1 //photocell 2
#define digitalPin1 3 //led 1
#define digitalPin2 4 //led 2

int analogInVar1;
int analogInVar2;
int digitalOutVar1;
int digitalOutVar2;

void setup (){
pinMode(analogPin1, INPUT);
pinMode (analogPin2, INPUT);
Serial.begin(9600);
}
void loop (){
analogInVar1 = analogRead(analogPin1);
analogInVar2 = analogRead(analogPin2);

Serial.print("Photocell 1 value: ");//get values
Serial.println(analogInVar1, DEC);
Serial.print("Photocell 2 value: ");
Serial.println(analogInVar2, DEC);

if (analogInVar1 < 30 && analogInVar2 < 800){
digitalWrite (3 , HIGH);
digitalWrite (4, LOW);
}
else{
digitalWrite (3, LOW);
digitalWrite (4, HIGH);
}
}

Here are some pictures:


The Interface


The Circuit

So from the code you can see that the wiring setup is fairly easy; the photocells go to analog pins 0 and 1 and the led's go to digial pins 3 and 4. The if statement is there to set the key to the lock - photo cell 1 must be < 30 and photo cell 2 must be <800 (I had wildly varient readings from the two photocells) for the led's to switch.

Observation Assignment (Parts 1 & 2)

I did both parts of the observation assignment at the Astor Place Starbucks, looking first at all visable cell phone and laptop interactions, then in depth at the cell phone interactions. Here is a general layout of the Starbucks and places at which a cell phone, a laptop, or both, were used:



Although I was there for over an hour, not a single laptop user closed up and went home, so every laptop on the diagram represents at least an hour's worth of interaction; be it more or less consant. Since I saw no opening or closing of laptops, no setup or breakdown, most of the visable interactive cues were indistingushable from one another, being of three simple catagories:

1.) Typing (placing the hands on the horizontal extention of the machine and pressing down with some frequency)

2.) Mouse (moving of the right or left hand while clutching a palm sized device; also involves the pressing down of digits, most noticably the index finger of the operating hand)

3.) Optical (Interaction with the vertical part of the machine, mostly achieved with the eyes, and sometimes ears; accompanied often, but not always, by one or both of the afmorementioned types of interactivity)

These various catagories of interaction changed and combined at such a high frequency and irregularity that timing of the individual actions proved impossible.

As cell phone interactions seemed to allow for a more diverse and easier to specify interaction set, I chose these devices to serve as my in depth observations.

I chose to break down the cell phone interactions into several catagories as well:

1.) Phone-to-ear (those interactions in which the user held the phone up to their ear)

2.) Phone-to-finger (those interactions in which the user pressed buttons on the phone)

3.) Phone-to-eye (those interactions in which no buttons were pressed, and phone was not held up to ear, but phone was clearly the focus of the user)

On the diagram below, I have separated the cell phone actions into these catagories, along with the frequency of the various interactions:



I also tallied one other catagory, which I dubbed 'transient' interactions. Those being the interactions I witnessed from those either taking orders to go, or those who were standing in line and then sat somewhere hidden from my view.

Of these, I witnessed:
PE: 4
PF: 6
PI: 9

Without going to far into the interpretation of the actions, it may be useful to comment that all of the 'transient' interactions occurred while the user was standing, whilst all other noted interactions were done while the user was sitting.

As best as I could calculate, the average duration of the various forms of interaction (transient interactions included) was thus:

PE: 8.5 Minutes
PF: 3.0 Minutes
PE: < 1 Minute

Without making too many assumptions regarding the exact usage of each type, it would seem as though the PE method was used when the greatest amount of time was needed to complete the interaction, involved the most constant interaction with the device, and thus was used when large amounts of information needed to be input to the device.

The PF method was used for a much shorter amount of time on average, implying that the amount and complexity of input was less then that of the phone-to-ear method. The frequency of user input was also much more dispersed in most cases.

Finally, the PI method involved the least and most basic input (none), as well as the shortest interaction time. We might conclude then, that the information gained or exchanged in these interactions is of a very simple variety.

As for ease with which the device was used, it appeared that all subjects were quite familiar with the layout of their cell phone, regardless of the type of interaction that was occurring. Although no 'failed' interactions were noted, subjects of the PF variety seemed to show the most distress either before or after their interaction. PE users sometimes showed negative reactions, though no notably change in their interaction with the device occurred. PI users, perhaps due to the short span of their interactions, did not typically display any significant reaction during or after their cell phone use.

All subjects were also, quite interestingly, acutely aware of where they kept the device when not in use. A fair number of seated subjects (six) actually kept their phone on the table whether it was in use or not. Of the transient users, an additional five users kept their phone in hand throughout my observation of them (notably shorter for the transient group).

In summary, this observation has been a most interesting and enlightening way to disect human/digital relations, and to look at how we deal with devices on a daily basis. I would have perhaps enjoyed looking at a less-familiar device, so that some failed interactions may have occurred, and perhaps led to some basic criticism of the device itself. However, being able to abstract the usability from the actual use is a valuable tool for evaluating the success of a design, and will surely come in handy in the future.

Week's 1-2 Summary

So, as I am a little bit late in creating this blog, I will just copy and paste the notes I took for the journal over the past two weeks:

Week 1:

I was very excited to get started with the lab, even though I have absolutely zero experience with physical computing, and as it turned out, the lab took me quite a while.

The first two parts of the lab actually turned out to be the most challenging for me. It seemed as though everything was infinately more complicated in 3d then on the page. This was largely due to the fact that I had resovled to attempt to learn from skematics only, seeing as how I wouldn't always have pictures to copy from.

While this proved to be very helpful on the last three excersises, the first two required a lot of trial and error. Even after I got some parts to work, I had to go back and try to understand why.

The most difficult parts for me was understanding how to read the 'flow' of the circuit on the breadboard, picking the right resistors, and confusing which elements needed grounding. However, by the end of the second excersise, I had begun to feel pretty comfortable with the elements involved. I also learned how exciting and amusing it can be to make an LED light up.

Week 2:


My biggest lesson from this week was in patience. Most of the excersise I had gotten through fairly quickly, though figuring which port was the right one took me a while, espically since there was only one USB port, and I had to try all the options a few different times before the program successfully downloaded. But oh, how satisfying.

But somehow, I had created some sort of randomizing switch instead of a realible one. The red and yellow LED's would switch, both be on, both be off, and would change at their own behest, regardless of what the button was doing.

I checked the code as best I could, re-sautered the wires, checked every connection, and found no reason. Jiggling certain wires seemed to increase the frequency of change, but try as I might, I could not isolate the problem.

Finally, (with some help) I realized that I had omitted the 10k ohm resistor. Since neither of the LED's seemed to be burning out, I had mistakely assumed that the resistence was correct.

So my lesson for the week is to always check resistence and make sure all your current is getting used in the right places.

Ben's P-Comp Blog

Ok, here we go...