Physical Computing: Day 2 – Physical Computing: Day 2 – Physical Computing: Day 2

Project 1Digital Input

Parts for this project:

• Solderless Breadboard
• 7 x Flexible Wire Jumpers - 1 x LEDs (any color)
• 2 x 220 Ohm Resistors
• 1 xTactile Pushbutton
• Arduino Duo board
• USB Cable

Button.ino

Pulse Width Modulation, or PWM, is a technique for getting analog results with digital means. Digital control is used to create a square wave, a signal switched between on and off. This on-off pattern can simulate voltages in between full on (5 Volts) and off (0 Volts) by changing the portion of the time the signal spends on versus the time that the signal spends off. The duration of "on time" is called the pulse width. To get varying analog values, you change, or modulate, that pulse width. If you repeat this on-off pattern fast enough with an LED for example, the result is as if the signal is a steady voltage between 0 and 5v controlling the brightness of the LED.

In the graphic below, the green lines represent a regular time period. This duration or period is the inverse of the PWM frequency. In other words, with Arduino's PWM frequency at about 500Hz, the green lines would measure 2 milliseconds each. A call to analogWrite() is on a scale of 0 - 255, such that analogWrite(255) requests a 100% duty cycle (always on), and analogWrite(127) is a 50% duty cycle (on half the time) for example.

Project 4Analog Input

Parts for this project:

• Solderless Breadboard
• 8 x Flexible Wire Jumpers
• 1 x RGB LED
• 3 x 220 Ohm Resistors
• 1 x Blue Potentiometer with white knob
• Arduino Duo board
• USB Cable

The Circuit

• Connect 5V and GND to the side strips
• Connect the short leads of the LED to pins 9,10,11 in series with a resistor.

• Connect the Potentiometer across 3 rows
• One side goes to ground.
• The other goes to +5V
• The Center Pin Connects to analog in 0 (Marked A0)

Upload 'RBG_Pot.ino'

The Potentiometer

RGB LED

int val = analogRead(analogPin);    // read the input pin
                    

Upload 'RBG_Pot_Serial.ino'

int LEDGreen=9;
int LEDBlue=10;
int LEDRed=11;

int sensorPin=0;
int val;


void setup(){
  Serial.begin(9600);
}

void loop(){
  
  val=analogRead(sensorPin);
  
  Serial.print("sensor = " );
  Serial.println(val);

  if (val<340) {
    analogWrite(LEDRed,255);
    analogWrite(LEDBlue,0); 
    analogWrite(LEDGreen,0);    
  } else if (val<680) {
    analogWrite(LEDRed,0);
    analogWrite(LEDBlue,255); 
    analogWrite(LEDGreen,0); 
  } else if (val<1024) {
    analogWrite(LEDRed,0);
    analogWrite(LEDBlue,0); 
    analogWrite(LEDGreen,255);  
  }
  delay(10);
}
                
            
                    

Upload 'SerialMath.ino'

int a = 5;
int b = 10;
int c = 20;

void setup()                    // run once, when the sketch starts
{
  Serial.begin(9600);           // set up Serial library at 9600 bps

  Serial.println("Here is some math: ");

  Serial.print("a = ");
  Serial.println(a);
  Serial.print("b = ");
  Serial.println(b);
  Serial.print("c = ");
  Serial.println(c);

  Serial.print("a + b = ");       // add
  Serial.println(a + b);

  Serial.print("a * c = ");       // multiply
  Serial.println(a * c);
  
  Serial.print("c / b = ");       // divide
  Serial.println(c / b);
  
  Serial.print("b - c = ");       // subtract
  Serial.println(b - c);
}

void loop()                     // we need this to be here even though its empty
{
}
                
            
                    

WE can send Serial data as well

Upload PhysicalPixel.ino

const int redPin = 9; // the pin that the LED is attached to
const int bluePin = 10; // the pin that the LED is attached to
const int greenPin = 11; // the pin that the LED is attached to
int incomingByte;      // a variable to read incoming serial data into

void setup() {
  // initialize serial communication:
  Serial.begin(9600);
  // initialize the LED pin as an output:
  pinMode(redPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
  pinMode(greenPin, OUTPUT);
}

void loop() {
  // see if there's incoming serial data:
  if (Serial.available() > 0) {
    // read the oldest byte in the serial buffer:
    incomingByte = Serial.read();
    // if it's a r , turn on the red LED:
    if (incomingByte == 'r') {
      digitalWrite(greenPin, LOW);
      digitalWrite(bluePin, LOW);
      digitalWrite(redPin, HIGH);
    }
    // if it's a g , turn on the green LED:
    if (incomingByte == 'g') {
      digitalWrite(greenPin, HIGH);
      digitalWrite(bluePin, LOW);
      digitalWrite(redPin, LOW);
    }
    / if it's a b , turn on the blue LED:
    if (incomingByte == 'b') {
      digitalWrite(greenPin, LOW);
      digitalWrite(bluePin, HIGH);
      digitalWrite(redPin, LOW);
    }
  }
}

                

RBG Color Mixing

Some Programs to Try:

RainbowRGB.ino

SimpleRGB.ino

RandomRGBFader.ino

Controlling a Servo

Servo_Sweep.ino

#include <servo.h>
Servo myservo; // create servo object to control a servo
// a maximum of eight servo objects can be created
int pos = 0; // variable to store the servo position

void setup() {
myservo.attach(9); // attaches the servo on pin 9 to the servo object }

void loop() {
for(pos = 0; pos < 180; pos += 1) // goes from 0 degrees to 180 degrees
}
{ myservo.write(pos); delay(15);
// in steps of 1 degree
// tell servo to go to position in variable 'pos'
// waits 15ms for the servo to reach the position
}
for(pos = 180; pos>=1; pos-=1) // goes from 180 degrees to 0 degrees 
{
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position 
}
</servo.h>

Servo With Potentiometer

Upload SERVO_KNOB.INO