最近买了个GAY-30光线传感器，这个型号也叫BH1750FVI。结果网上搜了一圈，没人写过Windows 10 IoT驱动这个传感器的例子，只能自己爆一个出来了。

光线传感器外观是这样的：

我用的板子是树莓派3，GPIO布局如下：

因为GAY-30是个I2C设备，所以我们不能用GPIO端口操作，必须用I2C方式去爆。并且因为这个特性，不支持热插拔。必须把树莓派关机，连接好传感器，再开机才能找到设备。这是坑了我很久的一个地方。

连接如下：

GAY-30针脚	树莓派端口	备注
VCC	PIN 01	3.3V电源正极
ADO	不接	没有什么卵用
SDA	PIN 03	SDA1 I2C
SCL	PIN 05	SLC1 I2C
GND	PIN 06	接地线，电源负极

 

然后就可以爆代码了：

先来看看Windows 10 IoT官网操作I2C的代码是这样的

I2C
        Pin 3 - I2C1 SDA
        Pin 5 - I2C1 SCL

using Windows.Devices.Enumeration;
using Windows.Devices.I2c;
 
public async void I2C()
{
    // Get a selector string for bus "I2C1"
    string aqs = I2cDevice.GetDeviceSelector("I2C1");
     
    // Find the I2C bus controller with our selector string
    var dis = await DeviceInformation.FindAllAsync(aqs);
    if (dis.Count == 0)
        return; // bus not found
     
    // 0x40 is the I2C device address
    var settings = new I2cConnectionSettings(0x40);
     
    // Create an I2cDevice with our selected bus controller and I2C settings
    using (I2cDevice device = await I2cDevice.FromIdAsync(dis[0].Id, settings))
    {
        byte[] writeBuf = { 0x01, 0x02, 0x03, 0x04 };
        device.Write(writeBuf);
    }
}

这里面有个神器的东西，就是

    // 0x40 is the I2C device address
    var settings = new I2cConnectionSettings(0x40);

这个0x40的地址是怎么得到的呢。。。

经过一番爆破，发现每个I2C硬件用的地址都不一样，一般要到对应硬件的说明文档里找。如果找不到，可以在Raspbian系统里按照这个方法去找：

http://www.raspberrypi-spy.co.uk/2014/11/enabling-the-i2c-interface-on-the-raspberry-pi/

我的这个GAY-30传感器的I2C地址是0x23，如果不出意外，所有这个型号的传感器在连接3.3V电源的时候都应该用0x23.

不多废话，经过一番爆破，贴出完整的GY30LightSensor驱动代码：

代码是参考Ardunio的版本写的。原帖在：http://blog.simtronyx.de/en/measurement-of-illuminance-with-a-bh1750fvi-breakout-board-gy-30-and-an-arduino-uno/ 

using System;
using System.Diagnostics;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Windows.Devices.Enumeration;
using Windows.Devices.I2c;

namespace GY30LightSensor
{
    public class GY30LightSensorEventArgs : EventArgs
    {
        public int? Lux { get; set; }

        public GY30LightSensorEventArgs(int? lux)
        {
            Lux = lux;
        }
    }

    public class GY30LightSensor
    {
        public int Bh1750Address => 0x23;

        public I2cDevice I2CLightSensor { get; private set; }

        private Timer PeriodicTimer { get; set; }

        public int TimerIntervalMs { get; set; }

        public event ReadingEventHandler Reading;

        public delegate void ReadingEventHandler(object sender, GY30LightSensorEventArgs e);

        private void OnReading(int lux)
        {
            Reading?.Invoke(lux, new GY30LightSensorEventArgs(lux));
        }

        public GY30LightSensor(int timerIntervalMs = 100)
        {
            TimerIntervalMs = timerIntervalMs;
        }

        public async Task InitLightSensorAsync()
        {
            string aqs = I2cDevice.GetDeviceSelector();
            /* Get a selector string that will return all I2C controllers on the system */
            var dis = await DeviceInformation.FindAllAsync(aqs);
            /* Find the I2C bus controller device with our selector string           */
            if (dis.Count == 0)
            {
                throw new FileNotFoundException("No I2C controllers were found on the system");
            }

            var settings = new I2cConnectionSettings(Bh1750Address)
            {
                BusSpeed = I2cBusSpeed.FastMode
            };

            I2CLightSensor = await I2cDevice.FromIdAsync(dis[0].Id, settings);
            /* Create an I2cDevice with our selected bus controller and I2C settings */
            if (I2CLightSensor == null)
            {
                throw new UnauthorizedAccessException(string.Format("Slave address {0} on I2C Controller {1} is currently in use by " +
                                 "another application. Please ensure that no other applications are using I2C.", settings.SlaveAddress, dis[0].Id));
            }

            /* Write the register settings */
            try
            {
                I2CLightSensor.Write(new byte[] { 0x10 }); // 1 [lux] aufloesung
            }
            /* If the write fails display the error and stop running */
            catch (Exception ex)
            {
                Debug.WriteLine("Failed to communicate with device: " + ex.Message);
                throw;
            }

            PeriodicTimer = new Timer(this.TimerCallback, null, 0, TimerIntervalMs);
        }

        private void TimerCallback(object state)
        {
            var lux = ReadI2CLux();
            OnReading(lux);
        }

        private int ReadI2CLux()
        {
            byte[] regAddrBuf = new byte[] { 0x23 };
            byte[] readBuf = new byte[2];
            I2CLightSensor.WriteRead(regAddrBuf, readBuf);

            // is this calculation correct?
            var valf = ((readBuf[0] << 8) | readBuf[1]) / 1.2; 

            return (int)valf;
        }
    }
}

使用方法：

public GY30LightSensor Gy30LightSensor { get; set; }

public MainPage()
{
    this.InitializeComponent();
    Gy30LightSensor = new GY30LightSensor();

    Loaded += OnLoaded;
}

private async void OnLoaded(object sender, RoutedEventArgs routedEventArgs)
{
    await Gy30LightSensor.InitLightSensorAsync();
    Gy30LightSensor.Reading += (o, args) =>
    {
        var task = this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
        {
            TxtLux.Text = args.Lux + " lx";
        });
    };
}

现在当有光线照射到传感器上的时候就可以得到流明（Lx）值了。

我也是刚刚才弄完，还没完整的验证过。我的代码里可能有个坑爹的地方就是Lx的计算。我不确定这个计算方式对不对：

var valf = ((readBuf[0] << 8) | readBuf[1]) / 1.2; 

如果有错还请读者指出~