Archive for the ‘Teaching’ category

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.

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));
}

iPhone Browser

October 6th, 2009

Perhaps the most typical network task performed by many network
applications is to load a web page.

The functionality of
Safari’s WebKit engine is available to you in the form of the UIWebView.

What we did

Created an application that loaded web pages.

  1. Open Xcode:

  2. Create a new Project (⌘+⇧+N). Make it a View-based
    Application

    view_based

  3. Name it Browser

  4. Open BrowserViewController.h and add pointers for IBOutlets
    for urlField (a UITextField) and webView (a UIWebView).

  5. This application brings up the keyboard. You will
    be managing a text field and you will want to dismiss the keyboard when the user either clicks a done button or presses return.

    To dismiss the keyboard, you need to tell the text field to give up its role
    as the first responder, meaning the component that initially receives
    the user input.
    [nameField resignFirstResponder];

    If you look up the documentation for UITextField, you’ll see that it has a delegate property
    that is defined by the UITextFieldDelegate protocol, a defined group of
    related methods.
    UItextFieldDelegate_doc

    Look up this protocol and you’ll see it has numerous
    methods that alert the delegate of events relating to the text field. One
    of them is textFieldShouldReturn, which looks like what you need in order
    to know when the user has tapped return.

    Add
    the UITextFieldDelegate protocol declaration too.


    @interface BrowserViewController : UIViewController <UITextFieldDelegate>{

  6. Add an instance
    method to handle the clicking of the go button. It will be of type IBAction Name it handleGoTapped.Pass it (id)sender

    Instance methods follow the closed curly brace and precede the @end

  7. Open the BrowserViewController nib in IB and create the User Interface.
    • A textField
    • A webView
    • A GO button

    Add a Placeholder in the textField so that the user knows to type http:// and set the keyboard to URL (⌘+1)

  8. Make the connections.
    (control-click the text field to expose its outlets, and connect
    its Delegate to File’s Owner.)

  9. Open up BrowserViewController.m. You’ll need to define the method to get the URL from
    the text field and have the web view load that site; this method will be
    called when the user clicks the Go button or when they hit Return
    on the pop-up keyboard.

    When the go button is pressed:

    1. Close the keyboard by calling resignFirstResponder on
      urlField

    2. Call loadURL on self

  10. To create the loadURL method
    1. Create a pointer named url of type NSURL and set it to:

      [[NSURL alloc] initWithString: urlField.text]

    2. Create a pointer named request
      of type NSURLRequest and set it to
      [[NSURLRequest alloc] initWithURL: url]

    3. Call loadRequest on webView and pass it request
    4. Release request
    5. Release url

  11. Add the following method:
    -(BOOL)textFieldShouldReturn:(UITextField *)textField {

    }

  12. Inside the method:
    1. Test if the textField equals the urlField

    2. Close the keyboard with resignFirstResponder
    3. Call loadURL on self
    4. Outside of the conditional, return YES

  13. Implement autoroatation
    -(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return ((interfaceOrientation == UIInterfaceOrientationPortrait) ||
    (interfaceOrientation == UIInterfaceOrientationLandscapeLeft) ||
    (interfaceOrientation == UIInterfaceOrientationLandscapeRight) ||
    (interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown));
    }

  14. Save, Build and Run

  15. Enter a url to test

  16. The most obvious thing lacking from
    the example is the usual forward and back buttons. You can
    implement them with the UIWebView’s goForward and goBack methods. Provide a delegate that implements the UIWebViewDelegate.

Part 2

All the substantial work in this application is done
by the UIWebView. Once you’ve loaded the page, this view — backed
by the WebKit engine for rendering HTML, interpreting JavaScript, and
handling the network communication — does all the work for handling your web interactions, including submitting forms, navigating to new
pages, running client-side browser apps, etc.

Even if you’re not planning on developing a browser, the UIWebView
has other compelling uses. While UIKit doesn’t provide a styled text
component for iPhone apps, you can style HTML to your heart’s content
with CSS, and put that styled HTML into a UIWebView. In fact, this is
an excellent way to provide an about screen for your application, as
you can provide links to your application’s home page, e-mails for tech
support, or even dialable phone number links, all by just authoring
HTML.
To do this, instead of loading a page from the web, you can include
your HTML, CSS, and images in the application bundle, and then find
them inside the bundle. Making a URL from a path in the bundle is just
a matter of converting the path string to an NSURL:

  1. Create a web page named mywebpage.html or use index.html

  2. In the
    <head></head> section add the following:
    <meta name="viewport" content="width=device-width; initial-scale=1.0;" />
    <meta name="viewport" content="width=320; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"/>
    <meta name="apple-mobile-web-app-capable" content="yes" />

  3. Set css body margin to zero

  4. Add the web page to your project. CTRL+click on Resources. Copy the file to your project.

  5. Create an application like you made in part 1, Name it Browser2.

  6. This application is the same as the previous except for the loadURLmethod. Create the IBOutlets and IBAction in the header file

  7. Open Browser2ViewController.xib create a text filed, web view and button. Make connections and CTRL+click on the textField and link it to the FIle Owner’s delegate.

  8. Open the Inspector and in the Text Field set the Text to webpage:

  9. This application is the same as the previous except for the loadURLmethod. Open Browser2ViewController.m file and define the IBAction method and then create the loadURLmethod

    //fill in the blank with a keyword to show your page
    //I did webpage:
    NSRange range = [urlField.text rangeOfString: @"______:"];
    NSURL *url = NULL;
    if (range.location == 0) {
    // find the about page in bundle

    NSString *myPath =
    //fill in the blank with the name of your page
    [[NSBundle mainBundle] pathForResource:@"______"
    ofType:@"html"];
    url = [[NSURL alloc] initFileURLWithPath: myPath];
    } else {
    url = [[NSURL alloc] initWithString: urlField.text];
    }
    if (url != NULL) {
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL: url];
    [webView loadRequest: request];
    [request release];
    [url release];

    }

  10. Add the following method:
    - (BOOL)textFieldShouldReturn:(UITextField *)textField {

    }

  11. Inside the method:
    1. Test if the textField equals the urlField

    2. Close the keyboard with resignFirstResponder
    3. Call loadURL on self
    4. Outside of the conditional, return YES

  12. Implement autoroatation
    -(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return ((interfaceOrientation == UIInterfaceOrientationPortrait) ||
    (interfaceOrientation == UIInterfaceOrientationLandscapeLeft) ||
    (interfaceOrientation == UIInterfaceOrientationLandscapeRight) ||
    (interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown));
    }

  13. Save, Build and Run

  14. Modify the loadURL method so that if the urlField is empty or if the urlField contains the text webpage:, your page gets loaded.

  15. Add the ability to go forward and back

More Objective-C Hello World

September 28th, 2009

So, the joke in class was “will there be a HelloWorld27?”

Probably not, but we are up to HelloWorld4.

So the class is small, but made up of students with very different programming backgrounds. Two of the students are very comfortable in the Revolution environment, but are having some difficulty getting used to the C syntax. The other four students have used Java and/or Arduino, and while the syntax is different, they are finding it easier to adapt what they know to what we are doing.

I find for some students pictures are essential.

HelloWorld04

  1. Create a an image of yourself with the following dimensions:
    dimension
  2. Save it as a png on the desktop

  3. Open Xcode and create a new project

  4. Create a View Based application
    view_based

  5. Save it as HelloWorld04

  6. Open up the HelloWorld04ViewController.h file

  7. Create a UILabel pointer named label of type IBOutlet

  8. Below the closed curly brace create an (IBAction) named hello and pass it (id)sender

  9. Open the Implementation file and define the hello function so that the text of label is set to a message

  10. Save the files

  11. CTRL+click on the Resources folder and add the png. Make sure to Copy items into destination group’s folder(if needed)

  12. Open up the main nib file

  13. Double click on the HelloWorld04ViewController in the MainWindow.xib
    viewController
  14. Click on the link
    link
  15. From the library add a UIImageView

  16. In the attribute window set the image to your png

  17. From the library drag a UILabel onto the view. Adjust the size

  18. Clear the Text in the Text field

  19. Choose a color for the text in the attribute window

  20. From the library drag a button on to the view and change the label on the button to Press Me

  21. In the xib window click on File’s Owner and press ⌘+2.

  22. Connect label to the label in the view.

  23. connect hello: to the button and select Touch up inside

  24. Save the xib file

  25. Build and run

  26. Modify the code so that the text keeps toggling between two expressions.
    animation
  27. Add an NSLog() statement to print out the current text to the console.

  28. Save the xib file

  29. Build and run (⌘+⇧+R)

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!

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!

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.

Hello World!

September 15th, 2009

clark

After spending the past summer gathering materials for my different classes, I thought it might be nice to share what I found inspiring, what I learned and how it all panned out.

Over the year, I will write about my experiences teaching Physical Computing, IPhone programming, and 2D and 3D animation to kids. I’ll try to explore what worked and what didn’t, what I would do again, and what I wouldn’t.

I’ve learned so much from various people, books and websites, and I hope that by sharing my thoughts, successes and failures, I can give back to a community that I have gotten so much from.

This is my first blog. wish me luck!