Exercise 1: Make a Processing Etch A Sketch
Working with an ellipse:
Arduino Code:
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
}
// the loop routine runs over and over again forever:
void loop() {
// read the input on analog pin 0:
int sensorValue1 = analogRead(A0);
int sensorValue2 = analogRead(A1);
// print out the value you read:
Serial.print(sensorValue1);
Serial.print(“,”);
Serial.print(sensorValue2);
Serial.println();
delay(1); // delay in between reads for stability
}
Processing Code:
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 **/
void setup() {
size(500, 500);
background(0);
setupSerial();
}
void draw() {
updateSerial();
printArray(sensorValues);
ellipse(sensorValues[0],sensorValues[1], 80, 80);
}
void setupSerial() {
printArray(Serial.list());
myPort = new Serial(this, Serial.list()[ 2 ], 9600);
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]);
}
}
}
}
}
Working with a line:
I modified the Processing code a bit to change from drawing with ellipse to line.
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 **/
int a;
int b;
void setup() {
size(800, 800);
background(255);
setupSerial();
}
void draw() {
updateSerial();
printArray(sensorValues);
fill(0);
line(a, b, sensorValues[0],sensorValues[1]);
a=sensorValues[0];
b=sensorValues[1];
void setupSerial() {
printArray(Serial.list());
myPort = new Serial(this, Serial.list()[ 2 ], 9600);
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]);
}
}
}
}
}
The difficult part in this drawing experience is that the potentiometer is difficult to control. From the video you can see that the lines I draw change abruptly – a result of the instability of potentiometers. I wonder if it is a problem of precision with our potentiometers?
Exercise 2: Make a musical instrument with Arduino
Processing Code:
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);
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);
// changes the values
for (int i=0; i<values.length; i++) {
values[0] = mouseX;
values[1] = mouseY;
/** 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 âeâ 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(13, OUTPUT);
pinMode(9, OUTPUT);
}
void loop() {
getSerialData();
//Serial.println(values[0]);
// add your code here
// use elements in the values array
// values[0] // values[1] if (values[0] > 150) {
if (values[0] == 1) {
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(âgjkgâ);
//switch â 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 â0ââŚâ9â˛:
//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 â â0â;
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 â,â:
values[valueIndex] = tempValue;
//reset tempValue value
tempValue = 0;
//increment valuesIndex by 1
valueIndex++;
break;
//if the char c from Processing is character ânâ
//which signals that it is the end of data
case ânâ:
//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 âeâ
//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 âeâ: // to echo
for (int i = 0; i < NUM_OF_VALUES; i++) {
Serial.print(values[i]);
if (i < NUM_OF_VALUES â 1) {
Serial.print(‘,’);
}
else {
Serial.println();
}
}
break;
}
}
