Arduino Workshop

The Arduino is a very small low-cost micro-computer test board.

It is perfect for learning to program or for building small automation projects. It is suitable even for people who had no experience with programming or electronics before, because there is no big step at the beginning of the learning process. The Arduino is Plug-and-Play, and the first steps are taken without difficulty and give a positive experience right away.

The software around the Arduino is fully free and open-source, including a simplified programming language similar to C++ and an easy to use graphical user interface for beginners. All of the software, the documentation and the hardware of the Arduino is open-source and freely available under the Creative Commons (CC-By-SA) license or the GNU Public License (GPL). That's why a lively community of users, hackers, hobbyists, and professional developers and engineers has evolved and produced a rich collection of tools, examples, tutorials, software libraries and more, all free and open-source.

The philosophy in the Arduino community is to learn, experience and share.

Shave & a hair-cut - 2 bits
/* Melody Plays a melody circuit: * 8-ohm speaker on digital pin 8 created 21 Jan 2010 modified 30 Aug 2011 by Tom Igoe modified 20 Apr 2013 by Jann Eike Kruse

This example code is in the public domain. http://arduino.cc/en/Tutorial/Tone */
 * 1) include "pitches.h"

// notes in the melody: int melody[] = { NOTE_C5, NOTE_G4, NOTE_G4, NOTE_A4, NOTE_G4, 0, NOTE_B4, NOTE_C5};

// note durations: 4 = quarter note, 8 = eighth note, etc.: int noteDurations[] = { 4, 8, 8, 4,4,4,4,4 };

void setup { // iterate over the notes of the melody: for (int thisNote = 0; thisNote < 8; thisNote++) {

// to calculate the note duration, take one second // divided by the note type. //e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.   int noteDuration = 1000/noteDurations[thisNote]; tone(8, melody[thisNote],noteDuration);

// to distinguish the notes, set a minimum time between them. // the note's duration + 30% seems to work well: int pauseBetweenNotes = noteDuration * 1.50; delay(pauseBetweenNotes); // stop the tone playing: noTone(8); } }

void loop { // no need to repeat the melody. }

Knock test
/* Knock Sensor This sketch reads a piezo element to detect a knocking sound. It reads an analog pin and compares the result to a set threshold. If the result is greater than the threshold, it writes "knock" to the serial port, and toggles the LED on pin 13. The circuit: * + connection of the piezo attached to analog in 1 * - connection of the piezo attached to ground * 1-megohm resistor attached from analog in 1 to ground

Previously on http://www.arduino.cc/en/Tutorial/Knock created 25 Mar 2007 by David Cuartielles  modified 30 Aug 2011 by Tom Igoe modified 20 Apr 2013 by Jann Eike Kruse This example code is in the public domain.

*/

// these constants won't change: const int ledPin = 13;     // led connected to digital pin 13 const int knockSensor = A1; // the piezo is connected to analog pin 1 const int threshold = 300; // threshold value to decide when the detected sound is a knock or not

// these variables will change: int sensorReading = 0;     // variable to store the value read from the sensor pin int ledState = LOW;        // variable used to store the last LED status, to toggle the light

void setup { pinMode(ledPin, OUTPUT); // declare the ledPin as as OUTPUT Serial.begin(9600);      // use the serial port }

void loop { // read the sensor and store it in the variable sensorReading: sensorReading = analogRead(knockSensor); // if the sensor reading is greater than the threshold: if (sensorReading >= threshold) { // toggle the status of the ledPin: ledState = !ledState; // update the LED pin itself: digitalWrite(ledPin, ledState); // send the string "Knock!" back to the computer, followed by newline Serial.println("Knock!"); delay(200); // delay to avoid overloading the serial port buffer } Serial.println(sensorReading); }

Knock Lock
/* Detects patterns of knocks and triggers a motor to unlock it if the pattern is correct. By Steve Hoefer http://grathio.com Version 0.1.10.20.10 Licensed under Creative Commons Attribution-Noncommercial-Share Alike 3.0 http://creativecommons.org/licenses/by-nc-sa/3.0/us/ (In short: Do what you want, just be sure to include this line and the four above it, and don't sell it or use it in anything you sell without contacting me.) Analog Pin 0: Piezo speaker (connected to ground with 1M pulldown resistor) Digital Pin 2: Switch to enter a new code. Short this to enter programming mode. Digital Pin 3: DC gear reduction motor attached to the lock. (Or a motor controller or a solenoid or other unlocking mechanisim.) Digital Pin 4: Red LED. Digital Pin 5: Green LED. Update: Nov 09 09: Fixed red/green LED error in the comments. Code is unchanged. Update: Nov 20 09: Updated handling of programming button to make it more intuitive, give better feedback. Update: Jan 20 10: Removed the "pinMode(knockSensor, OUTPUT);" line since it makes no sense and doesn't do anything. */ // Pin definitions const int knockSensor = 1;        // Piezo sensor on pin 0. const int programSwitch = 2;      // If this is high we program a new code. const int lockMotor = 13;         // Gear motor used to turn the lock. const int redLED = 4;             // Status LED const int greenLED = 5;           // Status LED // Tuning constants. Could be made vars and hoooked to potentiometers for soft configuration, etc. const int threshold = 250;        // Minimum signal from the piezo to register as a knock const int rejectValue = 25;       // If an individual knock is off by this percentage of a knock we don't unlock.. const int averageRejectValue = 15; // If the average timing of the knocks is off by this percent we don't unlock. const int knockFadeTime = 250;    // milliseconds we allow a knock to fade before we listen for another one. (Debounce timer.) const int lockTurnTime = 1000;     // milliseconds that we run the motor to get it to go a half turn.

const int maximumKnocks = 20;      // Maximum number of knocks to listen for. const int knockComplete = 1200;    // Longest time to wait for a knock before we assume that it's finished.

// Variables. int secretCode[maximumKnocks] = {50, 25, 25, 50, 100, 50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; // Initial setup: "Shave and a Hair Cut, two bits." int knockReadings[maximumKnocks];  // When someone knocks this array fills with delays between knocks. int knockSensorValue = 0;          // Last reading of the knock sensor. int programButtonPressed = false;  // Flag so we remember the programming button setting at the end of the cycle.

void setup { pinMode(lockMotor, OUTPUT); pinMode(redLED, OUTPUT); pinMode(greenLED, OUTPUT); pinMode(programSwitch, INPUT); Serial.begin(9600);              			// Uncomment the Serial.bla lines for debugging. Serial.println("Program start."); 			// but feel free to comment them out after it's working right. digitalWrite(greenLED, HIGH);     // Green LED on, everything is go. }

void loop { // Listen for any knock at all. knockSensorValue = analogRead(knockSensor); if (digitalRead(programSwitch)==HIGH){ // is the program button pressed? programButtonPressed = true;         // Yes, so lets save that state digitalWrite(redLED, HIGH);          // and turn on the red light too so we know we're programming. } else { programButtonPressed = false; digitalWrite(redLED, LOW); } if (knockSensorValue >=threshold){ listenToSecretKnock; } }

// Records the timing of knocks. void listenToSecretKnock{ Serial.println("knock starting");

int i = 0; // First lets reset the listening array. for (i=0;i<maximumKnocks;i++){ knockReadings[i]=0; } int currentKnockNumber=0;         			// Incrementer for the array. int startTime=millis;          			// Reference for when this knock started. int now=millis; digitalWrite(greenLED, LOW);     			// we blink the LED for a bit as a visual indicator of the knock. if (programButtonPressed==true){ digitalWrite(redLED, LOW);                        // and the red one too if we're programming a new knock. } delay(knockFadeTime);                       	        // wait for this peak to fade before we listen to the next one. digitalWrite(greenLED, HIGH); if (programButtonPressed==true){ digitalWrite(redLED, HIGH); } do { //listen for the next knock or wait for it to timeout. knockSensorValue = analogRead(knockSensor); if (knockSensorValue >=threshold){                  //got another knock...      //record the delay time. Serial.println(knockSensorValue); now=millis; knockReadings[currentKnockNumber] = now-startTime; currentKnockNumber ++;                            //increment the counter startTime=now; // and reset our timer for the next knock digitalWrite(greenLED, LOW); if (programButtonPressed==true){ digitalWrite(redLED, LOW);                      // and the red one too if we're programming a new knock. }     delay(knockFadeTime);                              // again, a little delay to let the knock decay. digitalWrite(greenLED, HIGH); if (programButtonPressed==true){ digitalWrite(redLED, HIGH); }   }

now=millis; //did we timeout or run out of knocks? } while ((now-startTime < knockComplete) && (currentKnockNumber < maximumKnocks)); //we've got our knock recorded, lets see if it's valid if (programButtonPressed==false){            // only if we're not in progrmaing mode. if (validateKnock == true){ triggerDoorUnlock; } else { Serial.println("Secret knock failed."); digitalWrite(greenLED, LOW); 		// We didn't unlock, so blink the red LED as visual feedback. for (i=0;i<4;i++){ digitalWrite(redLED, HIGH); delay(100); digitalWrite(redLED, LOW); delay(100); }     digitalWrite(greenLED, HIGH); } } else { // if we're in programming mode we still validate the lock, we just don't do anything with the lock validateKnock; // and we blink the green and red alternately to show that program is complete. Serial.println("New lock stored."); digitalWrite(redLED, LOW); digitalWrite(greenLED, HIGH); for (i=0;i<3;i++){ delay(100); digitalWrite(redLED, HIGH); digitalWrite(greenLED, LOW); delay(100); digitalWrite(redLED, LOW); digitalWrite(greenLED, HIGH); } } }

// Runs the motor (or whatever) to unlock the door. void triggerDoorUnlock{ Serial.println("Door unlocked!"); int i=0; // turn the motor on for a bit. digitalWrite(lockMotor, HIGH); digitalWrite(greenLED, HIGH);           // And the green LED too. delay (lockTurnTime);                   // Wait a bit. digitalWrite(lockMotor, LOW);           // Turn the motor off. // Blink the green LED a few times for more visual feedback. for (i=0; i < 5; i++){ digitalWrite(greenLED, LOW); delay(100); digitalWrite(greenLED, HIGH); delay(100); } }

// Sees if our knock matches the secret. // returns true if it's a good knock, false if it's not. // todo: break it into smaller functions for readability. boolean validateKnock{ int i=0; // simplest check first: Did we get the right number of knocks? int currentKnockCount = 0; int secretKnockCount = 0; int maxKnockInterval = 0;         			// We use this later to normalize the times. for (i=0;i 0){ currentKnockCount++; }   if (secretCode[i] > 0){  					//todo: precalculate this. secretKnockCount++; }   if (knockReadings[i] > maxKnockInterval){ 	// collect normalization data while we're looping. maxKnockInterval = knockReadings[i]; } }  // If we're recording a new knock, save the info and get out of here. if (programButtonPressed==true){ for (i=0;i 0){ delay( map(secretCode[i],0, 100, 0, maxKnockInterval)); // Expand the time back out to what it was. Roughly. digitalWrite(greenLED, HIGH); digitalWrite(redLED, HIGH); }       delay(50); }	 return false; 	// We don't unlock the door when we are recording a new knock. } if (currentKnockCount != secretKnockCount){ return false; } /*  Now we compare the relative intervals of our knocks, not the absolute time between them. (ie: if you do the same pattern slow or fast it should still open the door.) This makes it less picky, which while making it less secure can also make it     less of a pain to use if you're tempo is a little slow or fast. */ int totaltimeDifferences=0; int timeDiff=0; for (i=0;i rejectValue){ // Individual value too far out of whack return false; }   totaltimeDifferences += timeDiff; } // It can also fail if the whole thing is too inaccurate. if (totaltimeDifferences/secretKnockCount>averageRejectValue){ return false; } return true; }