Introduction
In this week’s recitation, we were given 2 exercises to complete. The purpose of these exercises is to make us familiar with sending values from Arduino to processing and the other way around. Most of the code has been provided from the examples, but we have to change the number of values and the function of the values.
Exercise 1: Etch-A-Sketch
This exercise focuses on sending values from Arduino to processing. We have to attach two potentiometers to the breadboard and let the values from the potentiometers control the direction of the line. For the first part, we were told to make an ellipse that is moving according to the values from the potentiometer. Below is the video:
The second part is where we have to change the ellipse to a line. We also have to use the previous value of the x and y position so that the line is continuous and smooth. Since the value read by the Arduino ranged from 0-1023, we have to map it to 0-255. This is the video of the final result:
Exercise 2: Musical Instrument
For the second one, the circuit is very simple as we only have to attach one buzzer to the breadboard. We use the tone function and use the value read from processing as the tone. In the processing, it reads the x and y position of the cursor and sends those values to Arduino. Below is the video:
Code:
Etch-a sketch
// 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 psensorValue0;
float psensorValue1;
void setup() {
size(500, 500);
background(255);
setupSerial();
}
void draw() {
updateSerial();
printArray(sensorValues);
float x = map(sensorValues[0], 0, 1023, 0, width);
float y = map(sensorValues[1], 0, 1023, 0, height);
stroke(0);
strokeWeight(2);
line( psensorValue0, psensorValue1, x, y);
psensorValue0 = x;
psensorValue1= y;
// use the values like this!
// sensorValues[0]
// add your code
//
}
void setupSerial() {
printArray(Serial.list());
myPort = new Serial(this, Serial.list()[ 3 ], 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[2];
}
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]);
}
}
}
}
}
void setup() {
Serial.begin(9600);
}
void loop() {
int sensor1 = analogRead(A0);
int sensor2 = analogRead(A1);
/// int sensor3 = analogRead(A2);
// map(sensor1, 0, 1023, 0, 255);
// keep this format
Serial.print(sensor1);
Serial.print(“,”); // put comma between sensor values
Serial.print(sensor2);
// Serial.print(“,”);
// Serial.print(sensor3);
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);
}
Musical Instrument
#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[2];
void setup() {
Serial.begin(9600);
pinMode(13, OUTPUT);
pinMode(9, OUTPUT);
}
void loop() {
getSerialData();
if (values [1] == true) { //if mouse is pressed which is at position 1 (which is mouse press) then…
tone(13, values[0]); //at pin 11 play the mouse x values frequency
}
else {
noTone(13);
}
}
//recieve serial data from Processing
void getSerialData() {
if (Serial.available()) {
char c = Serial.read();
//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;
}
}
}
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()[ 3 ], 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;//frequency is changing based on moving the mouse around, sends to arduino
values [1]=int(mousePressed);// turn true or false (boolean) into an integer that can be sent
// 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
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 );
}