ULTRASONIC SENSOR & LEDS

Using what we’ve learned about analog input and digital output, I chose to work with a digital in/out ultrasonic sensor and a digital output to LED. I wrote a program to control LEDs by distance to another object. By combining this with the enclosure work i’m doing in Fabrication, these simple components will transform into a robot!

Wiring for an ultrasonic sensor test.

A screenshot of the serial printing out the sensor values and then converting them to inches and centimeters. The sensor range reads as 120 - 5000 CHECK #, which is about 1 cm to 3 ft.

I first tested the ultrasonic sensor by itself using a code I found online, which showed me how to properly wire it and then also look at its reading through the serial. Ultrasonic sensors work kind of like echolocation, they send out a ping which will hit an object in front of it and then come back to the sensor. It measures the speed of the sound traveling to figure out distance. The peripheral scope is quite narrow, so the sensor will not detect anything coming from the side, however its frontal range is quite wide, being able to see as close as centimeters in front of it to as far as 3 feet.

For the code, I used different if statements to give the sensor thresholds for each LED. The result is that if the sensor detects an object very close it displays red, progressively further is yellow, and then finally green. The colors are symbolic to represent appropriate distance if you are respecting someone’s personal space.

After packaging the sensor, LEDs, and Arduino into an enclosure, the program really comes to life! See how I made the enclosure on my Fab blog.

Meet BubbL: The Personal Space Robot.

BubbL in action! Sound on to hear the constant ping of the ultrasonic sensor.

Interactive Technology Observation

Observation – 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.

As a Native New Yorker, I chose an infamous piece of interactive technology to observe: the MTA turn style. How it is used is fairly straight forward – swipe your Metrocard through the card reader and if you have a viable fare, you are granted passage.

However, rarely does it work that simply. It is almost as if you need to have the “magic touch” or have lived in NYC for so long you’re just “used to it”. As I observed, I saw many people swipe incorrectly, and the machine gives you a little lit up message like “Swipe again” or “Swipe again at this turnstyle” (which could probably be easily confused). The biggest source of confusion I noticed, was that the turnstyle makes a sound upon swiping, but this sound doesn’t change if its a good or bad swipe, thus, becuase commuters are often in a rush, they won’t see the small message and the sound indicates a swipe so they will go through the turn style with fortitude, only to be stopped like a game of red rover. And then they have to start the process over with a weird look back but with one foot forward. It’s awkward, it can be painful, and it ends up being inefficient.

MTA, may I advise a tap system.

ELECTRONICS LABS: Light 'em Up!

This week in physical computing we began to experiment with electronics, learning about circuits and different components. Using an Arduino, a microcontroller that connects to the computer, as my power supply, I tested different ways to wire an LED light bulb on a breadboard.

The breadboard allows me to connect wires and build circuits without having to solder (connecting wires with melted alloy – a more permanent connection). I especially wanted to get my hands on using the Arduino instead of just a battery or direct current power supply, so I could see how coding will play into mix.

Getting an LED to light up

A seemingly simple task, the first experiment was to light up a bulb. As I had learned from flashlight making this requires a circuit to carry electric current to the bulb and pass through to the ground. However, this exercise makes one delved deeper. LEDs only require a certain amount of voltage to light up, about 3 volts, too much voltage will actually make them burn out. This is where voltage regulators and resistors come in – to reduce the passage of current.

For this circuit, the Arduino allows us to eliminate the voltage regulator because we have a couple options of voltage we can output. By using the 5V pin and a 220 Ohm resistor, we reduce the voltage to an appropriate amount for the LED. Making sure all was in its proper place and using simple code, the light turns on and can even blink!

Me on Snapchat like…

YASSS

LED with Switch

A switch means you can essentially break the circuit and put it back together at a push of a button. The component used here is literally a “push button”, so when held down the current can pass through the whole circuit. When the button is released the circuit is broken.

Added a second LED, so they both light up with the switch.

Using a potentiometer

A potentiometer is a dial that controls the input of current. When turned all the way up, all 5 volts can pass through the circuit, turned down and the voltage will decrease eventually to 0. When connected to an LED, the potentiometer acts as a dimmer. When turned to 5V the LED is at its brightest. When the potentiometer is turned down, the light gradually dims until it turns completely off.

Switches in parallel

This wiring is kind of like a tree diagram. The power supply splits off into different branches, providing the same voltage but in different directions. With switches wired in parallel, any switch can turn the light on.

Switches in a series

This means the current travels down the line. The LED won’t light unless all switches are turned on at the same time.

Making my own switch

The possibilities for this were truly endless. A switch just needs to be something that completes the circuit. Since copper is super conductive, I decided to make my switch out of two pennies. There was a time we considered pulling pennies from circulation, so why not make it into something useful. Makes cents to me!

lol I’m sorry I’m done. k bye.

jk, final thoughts:

This lab was very exciting. It’s amazing to see how simply moving wires, pins, and components can make different things happen. I cannot stress enough how important it is that everything is wired correctly. Often one pin placed in the wrong row on the bread board was the culprit for something not working, and it could potentially damage everything. Lastly, the Arduino shows how something can become an extension of the computer. It takes information from my laptop and effects something outside the screen in the physical world. Sure, it was just lighting up LEDs and making switches, but I can definitely see how physical computing could have a larger impact and truly opens up the possibilities of technology and interaction.