張高興的 Windows 10 IoT 開發筆記：BH1750FVI 光照度傳感器

　　BH1750FVI 是一款 IIC 接口的數字型光強度傳感器集成電路。下面介紹一下其在 Windows 10 IoT Core 環境下的用法。

　　項目運行在 Raspberry Pi 2/3 上，使用 C# 進行編碼。

　　

　　1. 准備

　　包含 BH1750FVI 的傳感器，這里選擇的是淘寶上最多的 GY-30；Raspberry Pi 2/3 一塊，環境為 Windows 10 IoT Core；公母頭杜邦線 4-5 根

 

　　2. 連線

　　Raspberry Pi 2/3 的引腳如圖

　　由於采用的是 IIC 通信方式，因此我們需要把 GY-30 上的 SDA 與 Pin3 相連，SCL 與 Pin5 相連。VCC 接 3.3V，GND 接地。ADD 決定了傳感器的地址，將其連接至 VCC ≥ 0.7 V 的時候，地址為 0x5C，接地時為 0x23。可以不連接。

SDA - Pin3

SCL - Pin5

VCC - 3.3V

GND - GND

　　

 

　　3. 代碼

　　GitHub : https://github.com/ZhangGaoxing/windows-iot-demo/tree/master/BH1750FVIDemo　

　　需要新建一個 Windows 通用 項目 ，並且添加引用 Windows IoT Extensions for the UWP

　　在項目中添加一個 C# 代碼文件 BH1750FVI.cs，代碼如下

using System;
using System.Threading.Tasks;
using Windows.Devices.I2c;

namespace BH1750FVIDemo
{
    /// <summary>
    /// I2C Address Setting
    /// </summary>
    enum AddressSetting
    {
        /// <summary>
        /// ADD Pin connect to high power level
        /// </summary>
        AddPinHigh = 0x5C,
        /// <summary>
        /// ADD Pin connect to low power level 
        /// </summary>     
        AddPinLow = 0x23            
    };

    /// <summary>
    /// The mode of measuring
    /// </summary>
    enum MeasurementMode
    {
        /// <summary>
        /// Start measurement at 1 lx resolution
        /// </summary>
        ContinuouslyHighResolutionMode = 0x10,
        /// <summary>
        /// Start measurement at 0.5 lx resolution
        /// </summary>
        ContinuouslyHighResolutionMode2 = 0x11,
        /// <summary>
        /// Start measurement at 4 lx resolution
        /// </summary>
        ContinuouslyLowResolutionMode = 0x13,
        /// <summary>
        /// Start measurement at 1 lx resolution once
        /// </summary>
        OneTimeHighResolutionMode = 0x20,
        /// <summary>
        /// Start measurement at 0.5 lx resolution once
        /// </summary>
        OneTimeHighResolutionMode2 = 0x21,
        /// <summary>
        /// Start measurement at 4 lx resolution once
        /// </summary>
        OneTimeLowResolutionMode = 0x23
    }

    /// <summary>
    /// Setting light transmittance
    /// </summary>
    enum LightTransmittance
    {
        Fifty,
        Eighty,
        Hundred,
        Hundred_Twenty,
        Hundred_Fifty,
        Two_Hundred
    }

    class BH1750FVI
    {
        I2cDevice sensor;
        private byte sensorAddress;                             
        private byte sensorMode;
        private byte sensorResolution = 1;
        private double sensorTransmittance = 1;

        private byte registerHighVal = 0x42;
        private byte registerLowVal = 0x65;

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="address">Enumeration type of AddressSetting</param>
        /// <param name="mode">Enumeration type of MeasurementMode</param>
        public BH1750FVI(AddressSetting address, MeasurementMode mode)
        {
            sensorAddress = (byte)address;
            sensorMode = (byte)mode;

            if (mode == MeasurementMode.ContinuouslyHighResolutionMode2 || mode == MeasurementMode.OneTimeHighResolutionMode2)
            {
                sensorResolution = 2;
            }
        }

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="address">Enumeration type of AddressSetting</param>
        /// <param name="mode">Enumeration type of MeasurementMode</param>
        /// <param name="transmittance">Enumeration type of LightTransmittance</param>
        public BH1750FVI(AddressSetting address, MeasurementMode mode, LightTransmittance transmittance)
        {
            sensorAddress = (byte)address;
            sensorMode = (byte)mode;

            if (mode == MeasurementMode.ContinuouslyHighResolutionMode2 || mode == MeasurementMode.OneTimeHighResolutionMode2)
            {
                sensorResolution = 2;
            }

            switch (transmittance)
            {
                case LightTransmittance.Fifty:
                    {
                        registerHighVal = 0x44;
                        registerLowVal = 0x6A;
                        sensorTransmittance = 0.5;
                    }
                    break;
                case LightTransmittance.Eighty:
                    {
                        registerHighVal = 0x42;
                        registerLowVal = 0x76;
                        sensorTransmittance = 0.8;
                    }
                    break;
                case LightTransmittance.Hundred:
                    {
                        registerHighVal = 0x42;
                        registerLowVal = 0x65;
                    }
                    break;
                case LightTransmittance.Hundred_Twenty:
                    {
                        registerHighVal = 0x41;
                        registerLowVal = 0x7A;
                        sensorTransmittance = 1.2;
                    }
                    break;
                case LightTransmittance.Hundred_Fifty:
                    {
                        registerHighVal = 0x41;
                        registerLowVal = 0x7E;
                        sensorTransmittance = 1.5;
                    }
                    break;
                case LightTransmittance.Two_Hundred:
                    {
                        registerHighVal = 0x41;
                        registerLowVal = 0x73;
                        sensorTransmittance = 2;
                    }
                    break;
            }
        }

        /// <summary>
        /// Initialize BH1750FVI
        /// </summary>
        public async Task InitializeAsync()
        {
            var settings = new I2cConnectionSettings(sensorAddress);
            settings.BusSpeed = I2cBusSpeed.FastMode;                     

            var controller = await I2cController.GetDefaultAsync();
            sensor = controller.GetDevice(settings);

            sensor.Write(new byte[] { 0x01 });
            sensor.Write(new byte[] { registerHighVal });
            sensor.Write(new byte[] { registerLowVal });
        }

        /// <summary>
        /// Read data from BH1750FVI
        /// </summary>
        /// <returns>A double type contains data</returns>
        public double Read()
        {
            byte[] readBuf = new byte[2];

            sensor.WriteRead(new byte[] { sensorMode }, readBuf);

            byte temp = readBuf[0];
            readBuf[0] = readBuf[1];
            readBuf[1] = temp;

            double result = BitConverter.ToUInt16(readBuf, 0) / (1.2 * sensorResolution * sensorTransmittance);

            return result;
        }

        /// <summary>
        /// Cleanup
        /// </summary>
        public void Dispose()
        {
            sensor.Dispose();
        }
    }
}

　　下面解釋如何使用

　　代碼包含三個枚舉類型，兩個構造函數，三個方法。

　　第一步調用構造函數將 BH1750FVI 實例化。

　　第二步調用 InitializeAsync() 初始化 I2C 設備

　　第三步調用 Read() 讀取數據，返回的是一個 double 類型的值

　　當需要關閉設備時，調用 Dispose()