Arduino内置教程-通讯-串口呼叫响应ASCII

串口呼叫响应ASCII (握手)

这个例子示范了用呼叫响应（握手）方式从Arduino 或Genuino开发板到电脑的串口通讯。
这个程序在启动时发送一个ASCII 字符串，并且等它收到来自电脑的串口回应时重发。然后，它发送三个传感值作为 ASCII解码的数字（逗号分开，换行+回车结束），并且等待电脑的另一个回应。
你可以用Arduino IDE串口监视器来观察发送的数据，或者用Processing, Flash, PD, Max/MSP （看下面例子）等等来读取。下面的例子用逗号分开输入的字符串，并转换成字符串重新输入到数字里。
比较这个和串口呼叫响应例子。他们在共同使用的握手方式上很相似，但这个把读到的传感值作为字符串解码，而另一个作为二进制值发送。而发送像ASCII-encoded的字符串承载更多的字节，这意味着你可以很容易发送比255更大的字节的传感器读取值。它同样容易在串口终端程序里读取。

硬件要求

Arduino or Genuino 开发板
2 模拟传感器 (电位计, 光敏电阻, FSR 等)
按键
3 10K ohm 电阻
连接线
面包板

软件要求

Processing 或者 Max/MSP version 5

电路

把模拟传感器（作为分压器）通过10k ohm电阻连接到模拟引脚PIN0和PIN1。
把一个按键或者开关连接到数字I/O口pin2，并通过一个10k ohm电阻下拉到地。

请输入图片描述

原理图

请输入图片描述

样例代码

/*
  Serial Call and Response in ASCII
 Language: Wiring/Arduino

 This program sends an ASCII A (byte of value 65) on startup
 and repeats that until it gets some data in.
 Then it waits for a byte in the serial port, and
 sends three ASCII-encoded, comma-separated sensor values,
 truncated by a linefeed and carriage return,
 whenever it gets a byte in.

 Thanks to Greg Shakar and Scott Fitzgerald for the improvements

  The circuit:
 * potentiometers attached to analog inputs 0 and 1
 * pushbutton attached to digital I/O 2



 Created 26 Sept. 2005
 by Tom Igoe
 modified 24 Apr 2012
 by Tom Igoe and Scott Fitzgerald

 This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/SerialCallResponseASCII

 */

int firstSensor = 0;    // first analog sensor
int secondSensor = 0;   // second analog sensor
int thirdSensor = 0;    // digital sensor
int inByte = 0;         // incoming serial byte

void setup() {
  // start serial port at 9600 bps and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


  pinMode(2, INPUT);   // digital sensor is on digital pin 2
  establishContact();  // send a byte to establish contact until receiver responds
}

void loop() {
  // if we get a valid byte, read analog ins:
  if (Serial.available() > 0) {
    // get incoming byte:
    inByte = Serial.read();
    // read first analog input:
    firstSensor = analogRead(A0);
    // read second analog input:
    secondSensor = analogRead(A1);
    // read  switch, map it to 0 or 255L
    thirdSensor = map(digitalRead(2), 0, 1, 0, 255);
    // send sensor values:
    Serial.print(firstSensor);
    Serial.print(",");
    Serial.print(secondSensor);
    Serial.print(",");
    Serial.println(thirdSensor);
  }
}

void establishContact() {
  while (Serial.available() <= 0) {
    Serial.println("0,0,0");   // send an initial string
    delay(300);
  }
}


/*
Processing code to run with this example:

// This example code is in the public domain.

import processing.serial.*;     // import the Processing serial library
Serial myPort;                  // The serial port

float bgcolor;          // Background color
float fgcolor;          // Fill color
float xpos, ypos;           // Starting position of the ball

void setup() {
  size(640,480);

  // 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 module, so I open Serial.list()[0].
  // Change the 0 to the appropriate number of the serial port
  // that your microcontroller is attached to.
  myPort = new Serial(this, Serial.list()[0], 9600);

  // read bytes into a buffer until you get a linefeed (ASCII 10):
  myPort.bufferUntil('\n');

  // draw with smooth edges:
  smooth();
}

void draw() {
  background(bgcolor);
  fill(fgcolor);
  // Draw the shape
  ellipse(xpos, ypos, 20, 20);
}

// serialEvent  method is run automatically by the Processing applet
// whenever the buffer reaches the  byte value set in the bufferUntil()
// method in the setup():

void serialEvent(Serial myPort) {
  // read the serial buffer:
  String myString = myPort.readStringUntil('\n');
  // if you got any bytes other than the linefeed:
    myString = trim(myString);

    // split the string at the commas
    // and convert the sections into integers:
    int sensors[] = int(split(myString, ','));

    // print out the values you got:
    for (int sensorNum = 0; sensorNum < sensors.length; sensorNum++) {
      print("Sensor " + sensorNum + ": " + sensors[sensorNum] + "\t");
    }
    // add a linefeed after all the sensor values are printed:
    println();
    if (sensors.length > 1) {
      xpos = map(sensors[0], 0,1023,0,width);
      ypos = map(sensors[1], 0,1023,0,height);
      fgcolor = sensors[2];
    }
    // send a byte to ask for more data:
    myPort.write("A");
  }

*/

/*

Max/MSP version 5 patch to run with this example:
----------begin_max5_patcher----------
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-----------end_max5_patcher-----------

*/

[Get Code]

Processing 代码

从上面代码里复制Processing程序。随着你改变模拟传感器的值，你会获得一个在显示屏上运动的球，像这样。这个球只在你按下按钮时出现：
请输入图片描述