点亮LED和超声波测距

1. 点亮LED灯

   #include <Arduino.h>
   
   void setup()
   {
       pinMode(2,OUTPUT);  //  2号引脚为output模式
   }
   
   void loop()
   {
       digitalWrite(2,LOW);  //  低电平，打开LED
       delay(1000);
       //  休眠1000ms
       digitalWrite(2,HIGH);  //  高电平，关闭LED
       delay(1000);
   }

2. 超声波测量距离

   原理：发出一段高电平，检测高电平持续时间，利用高电平持续时间来计算传感器与物体之间的距离

   公式：(单位换算，输出时间为微秒，声速为343m/s)

   $$\Delta t \times 0.0343 \div 2$$

   #include <Arduino.h>
   
   #define TRIG  27  //  超声波与哪一个引脚相连
   #define ECHO  21
   
   void setup()
   {
       pinMode(TRIG,OUTPUT);  //  TRIG为输出模式
       pinMode(ECHO,INTPUT);  //  TRIG为输入模式
   }
   
   void loop()
   {
       digitalWrite(TRIG,HIGH);
       delayMicroseconds(10);  //  延时10微妙
       digitalWrite(TRIG,LOW);
       
       double delta_time = pulseln(ECHO,HIGH);  //检测高电平持续时间
       float detect_distance = delta_time * 0.0343 / 2;  //计算距离
       Serial.printf("distance=%f cm\n", detect_distance)
   }

3. 使用第三方库来驱动IMU（惯性测量器）

   arduino支持第三方库

   MP6050

   1. 引入开源库

      代理：http://github.fishros.org/

      lib_deps = https://github.com/fishros/MPU6050_light.git

   2. 修改代码

      在example中查看如何使用

      /* Get all possible data from MPU6050
       * Accelerometer values are given as multiple of the gravity [1g = 9.81 m/s²]
       * Gyro values are given in deg/s
       * Angles are given in degrees
       * Note that X and Y are tilt angles and not pitch/roll.
       *
       * License: MIT
       */
      
      #include "Wire.h"
      #include <MPU6050_light.h>
      
      MPU6050 mpu(Wire);
      
      
      void setup() {
        Serial.begin(115200);  //波特率
        Wire.begin(18,19);  //sda, scl初始化总线I^2C通信协议
        
        byte status = mpu.begin();
        Serial.print(F("MPU6050 status: "));
        Serial.println(status);
        while(status!=0){ } // stop everything if could not connect to MPU6050
        
        Serial.println(F("Calculating offsets, do not move MPU6050"));
        delay(1000);
        mpu.calcOffsets(true,true); // gyro and accelero
        Serial.println("Done!\n");
        
      }
      
      unsigned long timer = 0;
      
      void loop() {
        mpu.update();
      
        if(millis() - timer > 1000){ // print data every second
          Serial.print(F("TEMPERATURE: "));Serial.println(mpu.getTemp());
          Serial.print(F("ACCELERO  X: "));Serial.print(mpu.getAccX());
          Serial.print("\tY: ");Serial.print(mpu.getAccY());
          Serial.print("\tZ: ");Serial.println(mpu.getAccZ());
        
          Serial.print(F("GYRO      X: "));Serial.print(mpu.getGyroX());
          Serial.print("\tY: ");Serial.print(mpu.getGyroY());
          Serial.print("\tZ: ");Serial.println(mpu.getGyroZ());
        
          Serial.print(F("ACC ANGLE X: "));Serial.print(mpu.getAccAngleX());
          Serial.print("\tY: ");Serial.println(mpu.getAccAngleY());
          
          Serial.print(F("ANGLE     X: "));Serial.print(mpu.getAngleX());
          Serial.print("\tY: ");Serial.print(mpu.getAngleY());
          Serial.print("\tZ: ");Serial.println(mpu.getAngleZ());
          Serial.println(F("=====================================================\n"));
          timer = millis();
        }
      
      }