Tuesday, February 20, 2007
Lab 4 - Analog Out/Servos
For the analog out lab, I picked up a servo motor from the computer store and set the board up like the lab described. I got the servo working with the potentiometer and changed some of the numbers to adjust the range of motion. Whenever I think of servos, I utlimately associate them with animatronics and things of that nature. I rigged up a little scene in which a hand rises from the "grave" when the pot is turned. Need to work on set design some more. Photos show the scene.
Wednesday, February 14, 2007
Observation - Vending Machines
For my observation, I chose a bank of three vending machines in a building on campus. Each machine was slightly different which made for a different kind of interaction for each interface. The first machine was Poland Spring machine that had individual buttons for each drink. This was the simplest interface of the three. The other two machines were of the keypad variety. One was for snacks and the other for beverages.
My first thought was that the Poland Spring interface was the simplest and thus, quickest to use. Each interaction was essentially three parts. First, the person inserted their money. Next, they selected an item by either pushing the button that corresponded with their selection or punching the two digit code on the keypad for their selection. Lastly, they removed the item from the bottom of the machine. I would say each person spent 30 seconds with the machine on average. Some subjects that didn't know what they wanted took longer and some subjects ended up walking away from the machine empty handed after juggling their change around a bit.
On the whole, I was surprised by the efficiency of all of the interactions. Having had my fare share of awkward vending episodes, I thought that at least one person would have trouble getting money into the machine, figuring out what the item key code was, or getting the item out but nobody had this trouble. The time differences for using the two different interfaces was negligable contrary to what I originally thought. I still think that having a seperate button for each item is a more user friendly interface but it didn't seem to be a factor during my observations.
My first thought was that the Poland Spring interface was the simplest and thus, quickest to use. Each interaction was essentially three parts. First, the person inserted their money. Next, they selected an item by either pushing the button that corresponded with their selection or punching the two digit code on the keypad for their selection. Lastly, they removed the item from the bottom of the machine. I would say each person spent 30 seconds with the machine on average. Some subjects that didn't know what they wanted took longer and some subjects ended up walking away from the machine empty handed after juggling their change around a bit.
On the whole, I was surprised by the efficiency of all of the interactions. Having had my fare share of awkward vending episodes, I thought that at least one person would have trouble getting money into the machine, figuring out what the item key code was, or getting the item out but nobody had this trouble. The time differences for using the two different interfaces was negligable contrary to what I originally thought. I still think that having a seperate button for each item is a more user friendly interface but it didn't seem to be a factor during my observations.
Tuesday, February 13, 2007
Lab 3 - Analog In
For this lab I set up the board so that it would read analog input values. Setting this up was simple enough. I could dim the LED with the potentiometer. The only thing that gave me a problem was getting the values printed on the screen. After some clicking around I found the serial monitor was was reading the values from the potentiometer.
After I read out values from the potentiometer, I swapped it out and stuck in a photocell. I created the voltage divider and was dimming the LED by placing my hand over the cell. I noticed that the LED did not have as great a range as the potentiometer. The LED did not dim all the way either. That has to do with the qualities of the photocell. It might have had a lower absolute dark resistance meaning it is not as sensitive to low light and the resistance never went high enough to completely turn of the LED. Here are photos of the LED with my hand off and then on the photocell.
Unfortunately, after these two successes, I got stump. I attempted to read in values from a photocell that I had inserted into a practice drum pad to make a drum trigger that would output MIDI. I followed a tutorial from a site called TodBot and got code from the ITP site. My best efforts were thwarted and I can only hope to revisit this when we have do the MIDI output lab for class.
After I read out values from the potentiometer, I swapped it out and stuck in a photocell. I created the voltage divider and was dimming the LED by placing my hand over the cell. I noticed that the LED did not have as great a range as the potentiometer. The LED did not dim all the way either. That has to do with the qualities of the photocell. It might have had a lower absolute dark resistance meaning it is not as sensitive to low light and the resistance never went high enough to completely turn of the LED. Here are photos of the LED with my hand off and then on the photocell.
Unfortunately, after these two successes, I got stump. I attempted to read in values from a photocell that I had inserted into a practice drum pad to make a drum trigger that would output MIDI. I followed a tutorial from a site called TodBot and got code from the ITP site. My best efforts were thwarted and I can only hope to revisit this when we have do the MIDI output lab for class.
Monday, February 5, 2007
Lab 2- 1st Arduino Program
Everything went very smoothly with this lab. From, downloading and installing the Arduino software to getting the board up and running, I didn't run into a single snag which made the lab very fun.
This is the Arduino set up with the breadboard. The power is running from the Arduino to the breadboard with a switch hooked up to digital pin 2 with a pulldown resistor going to ground.
Here are the LED's. The yellow LED is normally on and when switch is pressed, the red LED lights up.
Here is a video of a sequence of 6 LED's running one after the next.
I switched the pins so that the sequence switched from one end to the next to give the illusion that the LED's were moving inward.
I attempted to use the voltage outputs to control an oscillator I made from a 555 chip. I couldn't generate enough voltage so I think I'll have to try again with an op-amp to boost the voltage. I might try a 741.
This is the Arduino set up with the breadboard. The power is running from the Arduino to the breadboard with a switch hooked up to digital pin 2 with a pulldown resistor going to ground.
Here are the LED's. The yellow LED is normally on and when switch is pressed, the red LED lights up.
Here is a video of a sequence of 6 LED's running one after the next.
I switched the pins so that the sequence switched from one end to the next to give the illusion that the LED's were moving inward.
I attempted to use the voltage outputs to control an oscillator I made from a 555 chip. I couldn't generate enough voltage so I think I'll have to try again with an op-amp to boost the voltage. I might try a 741.
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