从Arduino板子得到A0引脚模拟信号输入，发送串口数据到Processing程序中。Processing程序用收到的数据作图。

/*
  Graph

  A simple example of communication from the Arduino board to the computer: The
  value of analog input 0 is sent out the serial port. We call this "serial"
  communication because the connection appears to both the Arduino and the
  computer as a serial port, even though it may actually use a USB cable. Bytes
  are sent one after another (serially) from the Arduino to the computer.

  You can use the Arduino Serial Monitor to view the sent data, or it can be
  read by Processing, PD, Max/MSP, or any other program capable of reading data
  from a serial port. The Processing code below graphs the data received so you
  can see the value of the analog input changing over time.

  The circuit:
  - any analog input sensor attached to analog in pin 0

  created 2006
  by David A. Mellis
  modified 9 Apr 2012
  by Tom Igoe and Scott Fitzgerald

  This example code is in the public domain.

  http://www.arduino.cc/en/Tutorial/Graph
*/

void setup() {
  // initialize the serial communication:
  Serial.begin(9600);
}

void loop() {
  // send the value of analog input 0:
  Serial.println(analogRead(A0));
  // wait a bit for the analog-to-digital converter to stabilize after the last
  // reading:
  delay(2);
}

processing code:

//Processing code for this example

  // Graphing sketch

  // This program takes ASCII-encoded strings from the serial port at 9600 baud
  // and graphs them. It expects values in the range 0 to 1023, followed by a
  // newline, or newline and carriage return

  // created 20 Apr 2005
  // updated 24 Nov 2015
  // by Tom Igoe
  // This example code is in the public domain.

  import processing.serial.*;

  Serial myPort;        // The serial port
  int xPos = 1;         // horizontal position of the graph
  float inByte = 0;

  void setup () {
    // set the window size:
    size(400, 300);

    // List all the available serial ports
    // if using Processing 2.1 or later, use Serial.printArray()
    println(Serial.list());

    // I know that the first port in the serial list on my Mac is always my
    // Arduino, so I open Serial.list()[0].
    // Open whatever port is the one you're using.
    myPort = new Serial(this, Serial.list()[0], 9600);

    // don't generate a serialEvent() unless you get a newline character:
    myPort.bufferUntil('\n');

    // set initial background:
    background(0);
  }

  void draw () {
    // draw the line:
    stroke(127, 34, 255);
    line(xPos, height, xPos, height - inByte);

    // at the edge of the screen, go back to the beginning:
    if (xPos >= width) {
      xPos = 0;
      background(0);
    } else {
      // increment the horizontal position:
      xPos++;
    }
  }

  void serialEvent (Serial myPort) {
    // get the ASCII string:
    String inString = myPort.readStringUntil('\n');

    if (inString != null) {
      // trim off any whitespace:
      inString = trim(inString);
      // convert to an int and map to the screen height:
      inByte = float(inString);
      println(inByte);
      inByte = map(inByte, 0, 1023, 0, height);
    }
  }

20.png

19.png