Archive for the ‘Circuits’ category

Button Fun

November 3rd, 2009

This was my example. When you clicked the button, the face appeared and a sound file of a scream played.
I also suggested, to help students understand the interaction, that they could start with a picture of an animal, like a pig. If you clicked the tail, the image should change and a squeal should play.
surprise

iPhone Project with buttons and sound

  1. Create a background image

  2. Create a foreground image

  3. Create an icon image 57 x 57px

  4. Find a sound. Open the sound in Audacity and save as 32-bit sound.

  5. Open XCode

  6. Create a ViewBased Project

  7. Add the images and the sound

  8. Update the plist file

  9. Add a framework by CTRL+clicking on Frameworks. Select Existing Frameworks and add AudioToolbox.framework
    add_framework

  10. Open the header file

  11. Create a statement that imports the AudioToolbox/AudioToolbox.h

  12. Add 3 IBOutlets. One to hold a UILabel and the other two to hold pointers of type UIImageView

  13. Create a pointer of type NSTimer and name it resetTimer

  14. Create a a variable named sound of type SystemSoundID

  15. Create 3 @property declarations for the label and the UIImageViews

  16. Create a buttonPressed IBAction that takes sender of type id as its parameter.

  17. Open the implementation file

  18. @synthesize the properties

  19. Define the buttonPressed method:
    1. Set the text of your label to your message

    2. Create a pointer named foregroundImg of type UIImage and set it to the UIImage method imageNamed with the name of your foreground image as your parameter

    3. Set the image of the UIImageView that will pop up, to be the variable you just created (foregroundImg)

    4. Set the hidden property of that UIImageView to NO

    5. Test if sound and

      if the condition is met, then call:
      AudioServicesPlaySystemSound(sound);

    6. Test if resetTimer does NOT equal nil

      If the condition is met, then call:
      [resetTimer invalidate];

    7. Now set resetTimer to
      resetTimer = [NSTimer scheduledTimerWithTimeInterval:1.1 target:self selector:@selector(resetImages:) userInfo:nil repeats:NO];

  20. Now you have to define the method you just called (resetImages)


    - (void)resetImages:(NSTimer *)sender{

    }

  21. Inside the method:
    1. Set the hidden property of the UIImageView that pops up to YES

    2. Empty the label.

    3. Set resetTimer to nil

  22. Navigate to and uncomment viewDidLoad

  23. After the call to super, include these lines (remember to update the name of your audio file):

    CFBundleRef mainBundle = CFBundleGetMainBundle();
    CFURLRef soundUrlRef = CFBundleCopyResourceURL(mainBundle, CFSTR ("aaaah2"), CFSTR ("wav"), NULL);

    // Create a system sound object representing the sound file
    AudioServicesCreateSystemSoundID (soundUrlRef, &sound);

  24. Open the nib file and add a UIImageView

  25. Using the inspector set it to hold your background image
  26. Add a label

  27. Add a button
    bgImage

  28. Add another UIImageView and align it with the bottom
    bottom

  29. Connect The File Owner to label and select label
    to_label

  30. Connect the button to the File Owner and select buttonPressed
    btn

  31. Connect the File Owner to the UIImageView aligned to the bottom and select the name holding the UIImageView that pops up
    imageView

This project was inspired by Rory Lewis’s tutorials

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Posted in Circuits

Some early projects

November 2nd, 2009

Physical Computing

Here are a few of the recently completed projects:P1120064
FSR and LEDs

MovieA soft circuit button and LEDs

light4
Potentiometer controlled LEDs with 2 modes controlled by a button

img3
FSR controlled spooky eyes

A few other interesting projects are in the works. Two involve the capacitive sensor. The first uses a hacked disposable digital camera that flashes when the sensor is triggered. The second project was created as a Halloween installation. I hope there were pictures!

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Posted in Circuits, iPhone Programming

A Short Week

October 16th, 2009

I finished my soft circuit. Now when you pet it it purrs and flashes its eyes. I added a homemade capacitance sensor and a vibrating motor. I started with this information, but ended up using Paul Badger’s CapacitiveSense003 library which worked great. My circuit uses a 2.2MΩ resistor to connect pins 2 and 5 and the sensor itself is made of conductive frabric from LessEMF. The piece came from the Fabric Sample Set (Cat. #SAMPLER) and I cut in in half and connected it to pin 2 through conductive thread and a 22 AWG hookup wire.

Here’s the code:

#include
const int purr = 9; // pin that the LED is attached to
const int led = 3; // pin that the LED is attached to
const int eye1=10;
const int eye2=11;
const int mouth=4;
boolean purring=false;
boolean openEyes=false;
CapSense cs_1_2 = CapSense(1,2);

void setup(){
pinMode(purr, OUTPUT);
pinMode(led, OUTPUT);
pinMode(eye1, OUTPUT);
pinMode(eye2, OUTPUT);
pinMode(mouth, INPUT);
pinMode(led,OUTPUT);

pinMode(purr,OUTPUT);
digitalWrite(purr, LOW);
Serial.begin(9600);
}

int touch_sensor(){
long start = millis();
long total1 = cs_1_2.capSense(30);
if (total1<02){
return 1;
}else{
return 0;
}

/*Serial.print(millis() - start); // check on performance in milliseconds
Serial.print("\t"); // tab character for debug windown spacing

Serial.print(total1); // print sensor output 1
// print sensor output 3

delay(10); */
}

void loop(){
int touch=touch_sensor();
if (digitalRead(mouth)){
openEyes=true;
}
else{
openEyes=false;
}

if(!touch){
if(purring){
for(int i=255;i> 0;i-=10){
analogWrite(purr,i);
delay(20);
}

purring=false;
}
else{
analogWrite(purr,0);
openEyes=false;
}
digitalWrite(led,LOW);

}
else{
purring=true;
digitalWrite(led,HIGH);

analogWrite(purr,200);
openEyes=true;

}
if (openEyes){
for(int i=65;i<255;i+=10){
analogWrite(eye1,i);
analogWrite(eye2,i);
delay(10);
}
for(int i=255;i>65;i-=10){
analogWrite(eye1,i);
analogWrite(eye2,i);
delay(10);
}}else{
analogWrite(eye1,0);
analogWrite(eye2,0);
}
}


Students worked on their own soft circuits this week with different enthusiasm levels. Students used to working through labs, but not producing pieces, enjoyed this assignment far less than those who like to make crafts. Still, I believe introducing students to conductive thread and conductive fabrics will help them construct later projects.

We did run into a few glitches this week as well. One student plugged 12V into the freeduino. The 12V plug was used in our first experiments, and I had mentioned that the freeduino could be powered by the USB or a battery. I had extra Atmega chips and, apart from the chip, the board seemed fine.

Another student had trouble finding the usbserial port. At first I thought that the FTDI Drivers for Intel Macs was not installed, but then he moved to another computer with the same problem. His circuit seemed fine. In the end, it turned out that the USB cable was to blame. As soon as we switched cables, everything worked. It was a brand new cable and it surprised both of us that this was the source of the problems.

IPhone programming is going a bit slower than I anticipated. The class was still working on the second version of the Browser assignment this week. In the meantime, I came up with a way for students to create web pages to document their work:

Background-color:

Application name:

Notes:

File Name:


Code:

 

The Blender class is going well. Students have started working with armatures and materials. They have made short quicktime movies of the experiments and everyone is still engaged in the process.

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Posted in Blender, Circuits, Teaching, iPhone Programming

A cute soft circuit project

October 6th, 2009

Here’s a soft circuit with 2 LEDs and a button. It is basically an electronic sock puppet.

I used a sock covered in a knitted bag. The button is a sewing snap. When the mouth closes, the button returns a 1 and the LEDs flicker.

height="850" codebase='http://www.apple.com/qtactivex/qtplugin.cab'> controller="true" loop="false" pluginspage='http://www.apple.com/quicktime/download/'>

Here’s the code

#define btn 4
#define led1 3
#define led2 9
int btnState;

void setup(){
pinMode(led1,OUTPUT);
pinMode(led2,OUTPUT);
pinMode(btn,INPUT);

}

void loop(){
btnState=digitalRead(btn);
if(btnState){
for(int i=50;i<255;i+=5){
analogWrite(led1,i);
analogWrite(led2,i);
delay(10);
}
for(int i=255;i>100;i-=5){
analogWrite(led1,i);
analogWrite(led2,i);
delay(10);
}
}else{
digitalWrite(led1,LOW);
digitalWrite(led2,LOW);
}
Serial.println(digitalRead(btn));
}

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Posted in Circuits, Teaching

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Freeduinos!

September 30th, 2009

Both my middle school and high school classes worked on putting together the Freeduino kits.
yhst-82942516561161_2071_4704635
In order to avoid any soldering mistakes, I asked students to place all there resistors in the board first, and once I checked them, they could solder away. Capacitors were next, then LEDs then everything else. The middle school class had more success with putting the kits together quickly. Maybe soldering was more of a novelty for them? They completed their boards within two classes, but the high school students had the potential to drag the process into a third class. Rather than do that, I finished all but one of the boards. There was one high school student who completed his Freeduino over the weekend and worked on the Proto Shield from Adafruit in class.

My intention was to also have both groups make Proto Shields, but now I’m thinking that that project should be optional.

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A Tone Generator and a Cool Purchase

September 24th, 2009

A few years back, I took a summer physical computing class at Parsons with Dan Mikesell. For our first circuit he gave us the following schematic and image to work with:
555circuit555pinout
I like this assignment because it introduces an IC chip, the NE555 Timer, and it makes an awful noise when it works. I also like it because initially it seems hard, but when students take a moment to think about the connections, it turns out to be quite simple. I always tell students to start with the GND and Vcc pins and go from there. It’s like solving a puzzle.

After displaying the schematic, I hand out a bag with the components. For each student, or group of students, I remove the components from the bag, name them, and describe their function. Then I leave students alone to figure out the wiring.

Today was Middle School Physical Computing and it was the last class of the day. Everyone was exhausted, but we still managed to play with the LED Resistor Calculator and two students out of eight were able to generate annoying tones.

Success!

I also purchased the Makerbot CupCake CNC for school today. Makerbot describes the “CupCake CNC as a rock solid open source 3D printer that is easy to build, easy to run, and easy to use. Its 100% open source, built to be hacked, and beginner friendly.” The plan is to have the High School students research digital fabrication and then build the printer in November. Very cool!

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Posted in Circuits, Teaching

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Piranha Leds and LED Resistance Calculators

September 22nd, 2009

It was the first Middle School Physical Computing class of the week today. Class was split between two activities. The first was lighting a 5mm Flux RGB LED piranha. While not told whether they had a common cathode or common anode LED, students were given the following information:
rgb_piranha
DC forward current 20mA
Red: 2V typ, 2.4V max
Green: 3V typ, 3.6V max
Blue: 3V typ, 3.6V max

After determining their resistor values, each student wired up their circuits to discover if their led was common cathode or common anode. Only one student managed to burn out the led by wiring both sides to power.

After creating some blended colors, students put the lights aside and went on to construct Evil Mad Scientists’s LED Resistance Calculators.

Next class we’ll put the calculators to use and solve a few problems!

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Posted in Circuits, Teaching

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Our First IPhone App

September 21st, 2009

I’m teaching a year long iPhone programming class to middle school students. The only prerequisite for the class is one year of programming. Some of them have worked with Actionscript, Processing and Arduino. Others only have experience with Revolution.

I’ve tried to prepare the kids for the work that is involved. I’ve told them that graduate students at ITP were told that their iPhone programming class was going to be harder than any other programming class they’ve taken. In spite of my warnings, no one was scared off.

To get the ball rolling without talking about Objective-C, students worked on 2 simple applications. The first one, which is included below, is your basic Hello World app. In addition to creating a label, students also got to create their own icons for their applications.

The second application was a View-Based Application that modified the code in the implementation file so that the content could turn when the device is turned.

Everyone in the class completed the first part. There were two students that were confused about what a .png was and renamed their photoshop images with the .png extensions. After struggling to get their icons to show up, I’m pretty sure they won’t make that mistake again!

Overall, everyone was engaged and the energy level was high. Not bad for the last class of the day.

Hello World

xib files used to be called nib files and Apple continues to refer to them as nib files regardless of their extention.

Nib files are composed of several parts

  • File’s Owner
  • First Reponder
  • View—instance of UIView class

Part 1

  1. Open Xcode and create a new project (⌘+ ⇧+N)
    open_Xcode

  2. Select application under the iPhone icon on the left

  3. In the right panel select Window-Based Application, then press Choose. Save the project
    windows
  4. Double-click on the nib file to open
    Interface Builder
    nib

  5. Open Library (⌘+⇧+L)
    open_library

  6. Scroll down until you see a label icon.
  7. Drag from library to view

  8. Open Inspector (⌘+ ⇧+I)
    open_inspector
  9. Modify label so that you pick a size, color, drop shadow and a message.
    label_inspector

  10. Save

  11. In Xcode click on Build and Run

Interface Builder creates Objective-C objects and serializes those objects in to the nib file so that they can be loaded directly into memory at runtime.

Make sure that if you have an iPhone, your actual iPhone is not plugged into the computer while developing iPhone applications.

HelloWorld

Part 2

  1. Open your last project in the Simulator

  2. Click on the Home Icon
    home_icon

  3. Look at your application icon
  4. You need to create a .png icon 57 x 57 pixels. In Photoshop create your icon. Don’t worry about applying the button effect to it, it will happen automatically. Save it as icon.png

  5. Select the Resources folder and choose Add to Project from the Project menu and navigate to the icon. Choose Copy items into destination group’s folder(if needed).
    importing_icon
  6. In Xcode expand the Resources folder. Click once on Info.plist. This property list contains general information about the application you are building, including the name of the icon file.

  7. Find the row with the label Icon file. Double click on the empty cell to the right of the label and type in the name of your png file
    plist
  8. Locate Bundle identifier. The standard naming convention is to use com or org followed by a period, then the name of the organization, another period and the name of the application.

  9. compile and run

icon_view

Clearing out old icons

Under iPhone Simulator menu select Reset Content and Settings:
delete_icons

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The Second Time Around

September 17th, 2009

In order to wire the circuits and cover all the topics, I put the following information on the board before class started:

  • VF= Forward Voltage/ Voltage Drop.
    The minimum amount of voltage needed to light an LED

  • lV= Luminous Intensity
    The amount of light emitted from an LED in a particular direction.
    The greater the numbers the brighter the light.

  • IF= Forward Current
    The amount of current the LED uses.

  • Viewing Angle
    The distribution or spread of light.

And the following diagram:
Ohm's Law

Again, all materials were either distributed or placed on the floor in the middle of the group. Students worked together and everyone wired the first circuit using alligator clips, the second circuit using the 12VDC power supply and the third and fourth which wired the LEDs in series and then in parallel. In order to demonstrate the different voltage drops, the class experimented with different colored LEDs.

Flashing LEDs were thrown into the mix because they’re cool.

Today’s class was the last of the day and when it was over, some students stayed late to chat and help clean up.

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First Circuits with High School

September 16th, 2009

So today we wired up our first circuits. Before class started I put together boxes for each student with a breadboard, LEDs and a voltage regulator. When students came into class, I handed them their boxes and placed wires, batteries, alligator clips, wire cutters and strippers in the center of the room. Sitting on the floor, we started with nine volt batteries and LEDs with a forward voltage of 3V and a forward current of 0.03A. After using Ohm’s Law to figure out the resistance, we selected resistors and used alligator clips to make connections and light the LEDs.

The second circuit included a breadboard, a 12V DC power supply, an LM7805 voltage regulator, an LED and a resistor. As students were less confident about wiring up the voltage regulator and figuring out the new resistance, this circuit took a bit longer to complete.

voltage regulator detail

voltage regulator detail

After a final wiring check, power supplies were plugged in, and LEDs lit up.

The next circuits involved wiring LEDs in parallel and in series. The challenge here was to see how many could be lit in series and how many in parallel.

Forty-five minutes goes fast. Even though all the materials were prepared ahead of time, I didn’t get a chance to cover LED properties or the resistor values involved with illuminating an RGB LED in the way that I planned. No one had time to wire up the Piranhas, or High-Flux LEDs, and no one had a chance to clean up before running to their next class.

Type Color IF VF Typ VF Max Luminous Intensity Viewing Angle Wavelength
Standard Red 30mA 1.7V 2.1V 5mcd@10mA 60° 660nm
Standard Yellow 30mA 2.1V 2.5V 32mcd@20mA 60° 565nm
Super bright Red 30mA 1.85V 2.5V 500mcd@20mA 60° 660nm

Well, tomorrow I’ll get another shot at it when the Middle School Physical Computing class works on their first circuits.

This assignment was inspired by Syuzi Pakhchan’s book Fashioning Technology and from the first circuit I made at ITP in 1998.

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Posted in Circuits

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