指南针

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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

  • 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

compassMicroduino

compass_simulator

调试

步骤一:按着原理图搭建硬件环境,像这样:

Compass simulatorConnectionDiagram.jpg

下载这个HMC5883L的库函数: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:

Compass simulatorResult1.jpg

视频