Category: Interaction Lab

Exercise 1: Etch a Sketch

Creating this interactive Etch a Sketch was not too challenging, as it was fairly similar to something we learned to code in class when working through how to bring together Processing and Arduino.  In setting up this exercise (unlike the second one) it is very clear that the input information is coming from the Arduino and the two potentiometers, similar to that of a real etch a sketch.  In this way it makes sense that we are using Arduino to Processing, rather than the other way around because we can see the movements of the potentiometer being translated into designs on the screen.  

Processing Code:

// IMA NYU Shanghai
// Interaction Lab
// For receiving multiple values from Arduino to Processing

/*
 * Based on the readStringUntil() example by Tom Igoe
 * https://processing.org/reference/libraries/serial/Serial_readStringUntil_.html
 */


import processing.serial.*;

String myString = null;
Serial myPort;


int NUM_OF_VALUES = 2;   /** YOU MUST CHANGE THIS ACCORDING TO YOUR PROJECT **/
int[] sensorValues;      /** this array stores values from Arduino **/
float preX;
float preY;

void setup() {
  size(500, 500);
  background(100);
  setupSerial();
  //map(sensorValues, 0, 1023, 0, 255);
}


void draw() {
  map(sensorValues[0], 0, 1023, 0, 255);
  updateSerial();
  printArray(sensorValues);
  fill(0);
  //ellipse(sensorValues[0], sensorValues[1], 20, 20);
  
  float posX = map(sensorValues[0], 0, 1023, 0, width);
   
  float posY = map(sensorValues[1], 0, 1023, 0, height);
  
  line(preX, preY, posX, posY);
  // save current posX and posY to preX and preY
  preX = posX;
  preY = posY;
  
  
  
  // use the values like this!
  // sensorValues[0] 

  // add your code

  //

}

void setupSerial() {
  printArray(Serial.list());
  myPort = new Serial(this, Serial.list()[1], 9600);
  // WARNING!
  // You will definitely get an error here.
  // Change the PORT_INDEX to 0 and try running it again.
  // And then, check the list of the ports,
  // find the port "/dev/cu.usbmodem----" or "/dev/tty.usbmodem----" 
  // and replace PORT_INDEX above with the index number of the port.

  myPort.clear();
  // Throw out the first reading,
  // in case we started reading in the middle of a string from the sender.
  myString = myPort.readStringUntil( 10 );  // 10 = '\n'  Linefeed in ASCII
  myString = null;

  sensorValues = new int[NUM_OF_VALUES];
}



void updateSerial() {
  while (myPort.available() > 0) {
    myString = myPort.readStringUntil( 10 ); // 10 = '\n'  Linefeed in ASCII
    if (myString != null) {
      String[] serialInArray = split(trim(myString), ",");
      if (serialInArray.length == NUM_OF_VALUES) {
        for (int i=0; i<serialInArray.length; i++) {
          sensorValues[i] = int(serialInArray[i]);
        }
      }
    }
  }
}

Arduino Code:

// IMA NYU Shanghai
// Interaction Lab
// For sending multiple values from Arduino to Processing

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

void loop() {
int sensor1 = analogRead(A0);
int sensor2 = analogRead(A1);

// keep this format
Serial.print(sensor1);
Serial.print(“,”); // put comma between sensor values
Serial.print(sensor2);
Serial.println(); // add linefeed after sending the last sensor value

// too fast communication might cause some latency in Processing
// this delay resolves the issue.
delay(100);
}

Exercise 2: Making a Musical Instrument with Arduino

In making this musical instrument with the buzzer, it is clear that the variations in sounds being produced will come from the movement on the mousepad of my computer.  In this way it makes sense that we will be using Processing to Arduino to set up this exercise.  

After setting up the buzzer and then working in processing to make sure that my mouse movement was being recorded in values, the biggest challenge was making sure there was communication from Processing to Arduino.  I definitely made mistakes in this step, as initially I had different numbers of values in each program.  

Processing code:

// IMA NYU Shanghai
// Interaction Lab


/**
 * This example is to send multiple values from Processing to Arduino.
 * You can find the arduino example file in the same folder which works with this Processing file.
 * Please note that the echoSerialData function asks Arduino to send the data saved in the values array
 * to check if it is receiving the correct bytes.
 **/


import processing.serial.*;

int NUM_OF_VALUES = 2;  /** YOU MUST CHANGE THIS ACCORDING TO YOUR PROJECT **/


Serial myPort;
String myString;

// This is the array of values you might want to send to Arduino.
int values[] = new int[NUM_OF_VALUES];

void setup() {
  size(500, 500);
  background(0);

  printArray(Serial.list());
  myPort = new Serial(this, Serial.list()[ 2 ], 9600);
  // check the list of the ports,
  // find the port "/dev/cu.usbmodem----" or "/dev/tty.usbmodem----" 
  // and replace PORT_INDEX above with the index of the port

  myPort.clear();
  // Throw out the first reading,
  // in case we started reading in the middle of a string from the sender.
  myString = myPort.readStringUntil( 10 );  // 10 = '\n'  Linefeed in ASCII
  myString = null;
}


void draw() {
  background(0);
  
  values[0] = mouseX;
  values[1] = mouseY;
  //line(mouseX, 20, pmouseX, 80);   
  //println(mouseX + " : " + pmouseX);

  // changes the values
  //for (int i=0; i<values.length; i++) {
  //  values[i] = mouseX;  /** Feel free to change this!! **/
  //}

  // sends the values to Arduino.
  sendSerialData();

  // This causess the communication to become slow and unstable.
  // You might want to comment this out when everything is ready.
  // The parameter 200 is the frequency of echoing. 
  // The higher this number, the slower the program will be
  // but the higher this number, the more stable it will be.
  echoSerialData(200);
}

void sendSerialData() {
  String data = "";
  for (int i=0; i<values.length; i++) {
    data += values[i];
    //if i is less than the index number of the last element in the values array
    if (i < values.length-1) {
      data += ","; // add splitter character "," between each values element
    } 
    //if it is the last element in the values array
    else {
      data += "n"; // add the end of data character "n"
    }
  }
  //write to Arduino
   println(data);

  myPort.write(data);
}


void echoSerialData(int frequency) {
  //write character 'e' at the given frequency
  //to request Arduino to send back the values array
  if (frameCount % frequency == 0) myPort.write('e');

  String incomingBytes = "";
  while (myPort.available() > 0) {
    //add on all the characters received from the Arduino to the incomingBytes string
    incomingBytes += char(myPort.read());
  }
  //print what Arduino sent back to Processing
  print( incomingBytes );
}

Arduino code:

// IMA NYU Shanghai
// Interaction Lab

/**
This example is to send multiple values from Processing to Arduino.
You can find the Processing example file in the same folder which works with this Arduino file.
Please note that the echo case (when char c is ‘e’ in the getSerialData function below)
checks if Arduino is receiving the correct bytes from the Processing sketch
by sending the values array back to the Processing sketch.
**/

#define NUM_OF_VALUES 2 /** YOU MUST CHANGE THIS ACCORDING TO YOUR PROJECT **/

/** DO NOT REMOVE THESE **/
int tempValue = 0;
int valueIndex = 0;

/* This is the array of values storing the data from Processing. */
int values[NUM_OF_VALUES];

void setup() {
Serial.begin(9600);
pinMode(9, OUTPUT);
pinMode(13, OUTPUT);
}

void loop() {
getSerialData();
tone(9, map(values[0], 0, 500, 0, 1000), values[1]);
//Serial.println(values[0]);
// add your code here
// use elements in the values array
// values[0] // values[1] if (values[0] > 150) {
digitalWrite(13, HIGH);
} else {
digitalWrite(13, LOW);
}
//
// if (values[1] == 1) {
// tone(9, values[2]);
// } else {
// noTone(9);
// }

}

//recieve serial data from Processing
void getSerialData() {
if (Serial.available()) {
char c = Serial.read();
//Serial.println(“gjkg”);
//switch – case checks the value of the variable in the switch function
//in this case, the char c, then runs one of the cases that fit the value of the variable
//for more information, visit the reference page: https://www.arduino.cc/en/Reference/SwitchCase
switch (c) {
//if the char c from Processing is a number between 0 and 9
case ‘0’…’9′:
//save the value of char c to tempValue
//but simultaneously rearrange the existing values saved in tempValue
//for the digits received through char c to remain coherent
//if this does not make sense and would like to know more, send an email to me!
tempValue = tempValue * 10 + c – ‘0’;
break;
//if the char c from Processing is a comma
//indicating that the following values of char c is for the next element in the values array
case ‘,’:
values[valueIndex] = tempValue;
//reset tempValue value
tempValue = 0;
//increment valuesIndex by 1
valueIndex++;
break;
//if the char c from Processing is character ‘n’
//which signals that it is the end of data
case ‘n’:
//save the tempValue
//this will b the last element in the values array
values[valueIndex] = tempValue;
//reset tempValue and valueIndex values
//to clear out the values array for the next round of readings from Processing
tempValue = 0;
valueIndex = 0;
break;
//if the char c from Processing is character ‘e’
//it is signalling for the Arduino to send Processing the elements saved in the values array
//this case is triggered and processed by the echoSerialData function in the Processing sketch
case ‘e’: // to echo
for (int i = 0; i < NUM_OF_VALUES; i++) {
Serial.print(values[i]);
if (i < NUM_OF_VALUES – 1) {
Serial.print(‘,’);
}
else {
Serial.println();
}
}
break;
}
}