Digital Output: Blinking an LED
“Hello world” Basic debugging code.

led_blink example code

/* Blinking LED
* turns on and off a light emitting diode(LED) connected to a digital
* pin, in intervals of 2 seconds. Ideally we use pin 13 on the Arduino
* board because it has a resistor attached to it, needing only an LED
* Created 1 June 2005
* copyleft 2005 DojoDave
* http://arduino.berlios.de
* based on an orginal by H. Barragan for the Wiring i/o board
*/
int ledPin = 13; // LED connected to digital pin 13
void setup()
{
  pinMode(ledPin, OUTPUT); // sets the digital pin as output
}
void loop()
{
  digitalWrite(ledPin, HIGH); // sets the LED on
  delay(1000); // waits for a second
  digitalWrite(ledPin, LOW); // sets the LED off
  delay(1000); // waits for a second
}

Digital Read example code

/* Basic Digital Read
* turns on and off a light emitting diode(LED) connected to digital
* pin 13, when pressing a pushbutton attached to pin 7. It illustrates the
* concept of Active-Low, which consists in connecting buttons using a
* 1K to 10K pull-up resistor
* Created 1 December 2005
* copyleft 2005 DojoDave
* http://arduino.berlios.de
*/
int ledPin = 13; // choose the pin for the LED
int inPin = 7; // choose the input pin (for a pushbutton)
int val = 0; // variable for reading the pin status
void setup() {
  pinMode(ledPin, OUTPUT); // declare LED as output
  pinMode(inPin, INPUT); // declare pushbutton as input
}
void loop(){
  val = digitalRead(inPin); // read input value
  if (val == HIGH) { // check if the input is HIGH (button released)
   digitalWrite(ledPin, LOW); // turn LED OFF
  } else {
   digitalWrite(ledPin, HIGH); // turn LED ON
  }
}

Change pushbutton to tilt sensor and light sensor.

Analog Read/Send + Serial communication example code

/* Analog Read Send
* turns on and off a light emitting diode(LED) connected to digital
* pin 13. The amount of time the LED will be on and off depends on
* the value obtained by analogRead(). In the easiest case we connect
* a potentiometer to analog pin 2. Sends the data back to a computer
* over the serial port.
* Created 1 December 2005
* copyleft 2005 DojoDave
* http://arduino.berlios.de
*/
int potPin = 2; // select the input pin for the potentiometer
int ledPin = 13; // select the pin for the LED
int val = 0; // variable to store the value coming from the sensor
void setup() {
  pinMode(ledPin, OUTPUT); // declare the ledPin as an OUTPUT
  Serial.begin(9600); // use the serial port to send the values back to the computer
}
void loop() {
  val = analogRead(potPin); // read the value from the sensor
  Serial.println(val); // print the value to the serial port
  digitalWrite(ledPin, HIGH); // turn the ledPin on
  delay(val); // stop the program for some time
  digitalWrite(ledPin, LOW); // turn the ledPin off
  delay(val); // stop the program for some time
}

Reading a Parallax Ultrasound Sensor

Ultrasound Sensor example code

/* Ultrasound Sensor
* Reads values (00014-01199) from an ultrasound sensor (3m sensor)
* and writes the values to the serialport.
* http://www.xlab.se | http://www.0j0.org
* copyleft 2005 Mackie for XLAB | DojoDave for DojoCorp
*/
int ultraSoundSignal = 7; // Ultrasound signal pin
int val = 0;
int ultrasoundValue = 0;
int timecount = 0; // Echo counter
int ledPin = 13; // LED connected to digital pin 13
void setup() {
  beginSerial(9600);// Sets the baud rate to 9600
  pinMode(ledPin, OUTPUT);// Sets the digital pin as output
}
void loop() {
  timecount = 0;
  val = 0;
  pinMode(ultraSoundSignal, OUTPUT); // Switch signalpin to output
  /* Send low-high-low pulse to activate the trigger pulse of the sensor
  * ——————————————————————-
  */
  digitalWrite(ultraSoundSignal, LOW); // Send low pulse
  delayMicroseconds(2); // Wait for 2 microseconds
  digitalWrite(ultraSoundSignal, HIGH); // Send high pulse
  delayMicroseconds(5); // Wait for 5 microseconds
  digitalWrite(ultraSoundSignal, LOW); // Holdoff
  /* Listening for echo pulse
  * ——————————————————————-
  */
  pinMode(ultraSoundSignal, INPUT); // Switch signalpin to input
  val = digitalRead(ultraSoundSignal); // Append signal value to val
  while(val == LOW) { // Loop until pin reads a high value
    val = digitalRead(ultraSoundSignal);
  }
  while(val == HIGH) { // Loop until pin reads a low value
    val = digitalRead(ultraSoundSignal);
    timecount = timecount +1; // Count echo pulse time
  }
  /* Writing out values to the serial port
  * ——————————————————————-
  */
  ultrasoundValue = timecount; // Append echo pulse time to ultrasoundValue
  serialWrite(‘A’); // Example identifier for the sensor
  printInteger(ultrasoundValue);
  serialWrite(10);
  serialWrite(13);
  /* Light up LED if any value is passed by the echo pulse
  * ——————————————————————-
  */
  if(timecount > 0){
    digitalWrite(ledPin, HIGH);
  }
  /* Delay of program
  * ——————————————————————-
  */
  delay(100);
}

Reading a Memsic 2125 Dual Axis Accelerometer

Accelerometer sensor example code

/* Accelerometer Sensor
* Reads an 2-D accelerometer attached to a couple of digital inputs
* and sends their values over the serial port;
* makes the monitor LED blink once sent
* http://www.0j0.org
* copyleft 2005 K3 – Malmo University – Sweden
* @author: Marcos Yarza
* @hardware: Marcos Yarza
* @project: SMEE – Experiential Vehicles
* @sponsor: Experiments in Art and Technology Sweden, 1:1 Scale
*/
int ledPin = 13;
int xaccPin = 7;
int yaccPin = 6;
int value = 0;
int accel = 0;
char sign = ‘ ‘;
int timer = 0;
int count = 0;
void setup() {
  Serial.begin(9600); // Sets the baud rate to 9600
  pinMode(ledPin, OUTPUT);
  pinMode(xaccPin, INPUT);
  pinMode(yaccPin, INPUT);
}

/* (int) Operate Acceleration
* function to calculate acceleration returns an integer
*/
int operateAcceleration(int time1) {
  return abs(8 * (time1 / 10 – 500));
}

/* (void) readAccelerometer
* procedure to read the sensor, calculate acceleration and represent the value
*/
void readAcceleration(int axe){
  timer = 0;
  count = 0;
  value = digitalRead(axe);
  while(value == HIGH) { // Loop until pin reads a low
    value = digitalRead(axe);
  }
  while(value == LOW) { // Loop until pin reads a high
    value = digitalRead(axe);
  }
  while(value == HIGH) { // Loop until pin reads a low and count
    value = digitalRead(axe);
    count = count + 1;
  }
  timer = count * 18; //calculate the teme in miliseconds
  //operate sign
  if (timer > 5000){
    sign = ‘+’;
  }
  if (timer < 5000){
    sign = ‘-’;
  }

  //determine the value
  accel = operateAcceleration(timer);

  //Represent acceleration over serial port
  if (axe == xaccPin){
    Serial.print(‘X’);
  } else {
    Serial.print(‘Y’);
  }
  Serial.print(sign);
  Serial.print(accel);
  Serial.println();
}
void loop() {
  readAcceleration(xaccPin); //reads and represents acceleration X
  readAcceleration(yaccPin); //reads and represents acceleration Y
  digitalWrite(ledPin, HIGH);
  delay(300);
  digitalWrite(ledPin, LOW);
}