查看“指南针”的源代码

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==目的==

本教程将教大家如何用Microduino-10DOF模块测到的磁场强度数据在Processing中显示一个指南针。

==设备==
*'''[[Microduino-Core/zh]]'''
*'''[[Microduino-USBTTL/zh]]'''
*'''[[Microduino-10DOF/zh]]'''

*其他硬件设备
**USB数据连接线   一根

==原理图==

直接使用Microduino-10DOF上的HMC5883L磁场强度传感器

==程序==

[https://github.com/Microduino/Microduino_Tutorials/tree/master/Microduino_Processing/compassMicroduino compassMicroduino]

[https://github.com/Microduino/Microduino_Tutorials/tree/master/Microduino_Processing/compass_simulator compass_simulator]

==调试==

步骤一：按着原理图搭建硬件环境，像这样：
[[File:compass_simulatorConnectionDiagram.jpg|600px|center|thumb]]
下载这个HMC5883L的库函数：[https://github.com/manifestinteractive/arduino/tree/master/Libraries/HMC5883L HMC5883L]

步骤二：解释一下代码：

本例需要两端的代码，Processing端和Microduino端

Microduino:

在setup()中主要是初始化HMC5883L

在loop()中计算出周围磁感应的角度

//Output()用来输出计算出的角度到串口
  // Output the data down the serial port.
  void Output(int RoundDegreeInt)
  {
    //Serial.println();
    Serial.println(RoundDegreeInt);
    delay(150);
  }

Processing:

//得到第一个串口的数据.
  myPort = new Serial(this, Serial.list()[0], 9600);

//在draw()函数中，第一步得到串口传来的数据
  while (myPort.available() > 0) {
    myString = myPort.readStringUntil(lf);
    if (myString != null) {
  //print(myString);  // Prints String
    angle=float(myString);  // Converts and prints float
    println(angle);
    }
  }
  translate(160, 50);

//绘制指南针的背景
  // draw the compass background
  ellipseMode(CENTER);
  fill(50);
  stroke(10);
  strokeWeight(2);
  ellipse(150,150,300,300);


//绘制线和点
  // draw the lines and dots
  translate(150,150);  // translate the lines and dots to the middle of the compass
  float CompassX = -angle;
  rotate(radians(CompassX));
  noStroke();
  fill(51, 255, 51);
  int radius = 120;
  for( int degC = 5; degC < 360; degC += 10) //Compass dots
  {
    float angleC = radians(degC);
    float xC = 0 + (cos(angleC)* radius);
    float yC = 0 + (sin(angleC)* radius);
    ellipse(xC,yC, 3, 3);
  }
  for( int degL = 10; degL < 370; degL += 10) //Compass lines
  {
    float angleL = radians(degL);
    float x = 0 + (cos(angleL)* 145);
    float y = 0 + (sin(angleL)* 145);
    if( degL==90 || degL==180 || degL==270 || degL==360) {
     stroke(51, 255, 51);
     strokeWeight(4);
    }
    else {
      stroke(234,144,7);
      strokeWeight(2);
    }
    line(0,0, x,y);
  }
  fill(102, 102, 102);
  noStroke();
  ellipseMode(CENTER);
  ellipse(0,0, 228,228); //draw a filled circle to hide the lines in the middle



//绘制指南针的方向表示，东西南北
  b = loadFont("Arial-BoldMT-48.vlw");
  textAlign(CENTER);
  // Draw the letters
  fill(250);
  textFont(b, 32);
  text("N", 1, -90);
  rotate(radians(90));
  text("E", 0, -90);
  rotate(radians(90));
  text("S", 0, -90);
  rotate(radians(90));
  text("W", 0, -90);
  rotate(radians(90));
  textFont(b,40);
  textAlign(CENTER);
  //text((angle), 20, 20);
  println(angle);


//绘制指南针
  //draw the needle
  rotate(radians(-CompassX)); //make it stationary
  stroke(234,144,7);
  strokeWeight(3);
  triangle(-10, 0, 10, 0, 0, -85);
  fill(234,144,7);
  triangle(-10, 0, 10, 0, 0, 60);

步骤三：下载代码并编译通过。

步骤四：运行后，用一块磁铁改变一下磁场，看看指针是否变化。

==结果==

屏幕上会显示一个简单的指南针，指针会随着磁场走，像这样：
[[File:compass_simulatorResult1.jpg|600px|center|thumb]]

==视频==


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