Recitation 08: Serial Communication by Jiayi Liang(Mary)

During this recitation, we are told to make a processing Etch A Sketch and a musical instrument with arduino. The circuit is quite simple.  What we should do is only connecting two potentiometers. However, for me, writing the code is very challenging. Using the examples given, we try to send messages from arduino to processing and from processing to arduino.

Exercise 1

The first step is to use the potentiometers to control the position of a circle.  I succeeded at once, however, there is one problem that the circle will sometimes be out of the canvas.

Arduino:

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

void loop() {
int sensor1 = analogRead(A0);
int sensor2 = analogRead(A2);

//int mappedsensor1 = map(sensor1,0,1023,0,255);
//int mappedsensor2 = map(sensor2,0,1023,0,255);

// 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);
}

Processing:

 

So in the second step, the fellow tell me that maybe I can use the map() to adjust the position of the image. At the beginning I am stuck in “how to draw a line”, but soon after that I realize I just have to let the beginning point to be the previous sensorValue and the endpoint to be the current sensorValue.

Processing:

 

Exercise 2

In this exercise, we use mouse to control the sound of a buzzer. We use the sample code for multiple values from processing to arduino. The mouseX is the frequency of the tune and the mouseY is the duration.

Processing:

// 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()[ 9], 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;

  // changes the values
  // 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 );
}