c# - 使用 C# 在 Windows IOT 和 Arduino Nano 之间进行 I2C 连接

Question

我对 Raspberry 和 Arduino(尤其是 Windows IoT)的世界还很陌生。我的计划是，用 Arduino 读出不同的传感器(温度和压力)，然后将值发送到我的 RP2，我可以在 GUI 上使用它们。

因此，读出传感器不是问题。我收到正确的值。之后我将它们发送到 I²C 总线(基于 Wire.h 库的要求)。

对于我的 RP2，我发现了两个类似的项目，我的 C# 代码基于这些项目。

到目前为止一切顺利，但是当我启动这两个设备时，我的 RP 上没有任何数据。我的 RP 找到了 Arduino。

为了定位问题，我使用 Wire.h 示例草图将随机值发送到我的 RP。但是还是有同样的问题，所以我猜是我的C#代码有问题。我还在我的 RP 应该将值写入数组的地方设置了一个断点。但看起来，没有传入值。

我附上了两个代码。希望有人能帮助我。我卡得很厉害...

非常感谢! 蒂莫

Arduino 代码:

#include <Wire.h>
  #define SLAVE_ADDRESS 0x40


byte val = 0;
byte val_2 = 100;

void setup()
{
  Wire.begin(SLAVE_ADDRESS); // join i2c bus
  Serial.begin(9600);
}

void loop()
{
  Wire.beginTransmission(SLAVE_ADDRESS); // transmit to master device
                              // device address is specified in datasheet
  Wire.write(val);             // sends value byte  
  Wire.write (val_2);
 // Serial.write(val);
//  Serial.write(val_2);
  Wire.endTransmission();     // stop transmitting

  val++;        // increment value
  val_2++;
  if(val == 64) // if reached 64th position (max)
  {
    val = 0;    // start over from lowest value
  }

  if (val_2 == 164)
  {
    val = 100;  
  }
  delay(500);
}

C#代码:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
// i2c Libs
using Windows.Devices.Enumeration;
using Windows.Devices.I2c;
using System.Diagnostics;
using System.Threading;


// Die Vorlage "Leere Seite" ist unter http://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409 dokumentiert.

namespace _007_Test7_I2C
{
    /// <summary>
    /// Eine leere Seite, die eigenständig verwendet werden kann oder auf die innerhalb eines Rahmens navigiert werden kann.
    /// </summary>

    public sealed partial class MainPage : Page
    {

        private I2cDevice Device;
        private Timer periodicTimer;


        public MainPage()
        {
            this.InitializeComponent();
            initcomunica();
        }

        private async void initcomunica()

        {

            var settings = new I2cConnectionSettings(0x40); // Arduino address
            settings.BusSpeed = I2cBusSpeed.StandardMode;
            string aqs = I2cDevice.GetDeviceSelector("I2C1");
            var dis = await DeviceInformation.FindAllAsync(aqs);
            Device = await I2cDevice.FromIdAsync(dis[0].Id, settings);
            periodicTimer = new Timer(this.TimerCallback, null, 0, 1000); // Create a timer

        }

        private void TimerCallback(object state)
        {

            byte[] RegAddrBuf = new byte[] { 0x40 };
            byte[] ReadBuf = new byte[7];

            try
            {
                Device.Read(ReadBuf);
             //   Debug.WriteLine(ReadBuf);
            }
            catch (Exception f)
            {
                Debug.WriteLine(f.Message);
            }


            char[] cArray = System.Text.Encoding.UTF8.GetString(ReadBuf, 0, 7).ToCharArray();  // Converte  Byte to Char
            String c = new String(cArray);
            Debug.WriteLine(c);
            // refresh the screen, note Im using a textbock @ UI

            var task = this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            { Temp_2.Text = c; });

        }

    }
}

Answer 1

您的代码必须在两端同步。 Arduino 是 I2C Slave，只能根据 RPi2 (Windows IoT) 主机的请求发送字节。

您的 Arduino Sketch 中存在以下错误:

• Slave设备不能在总线上发起写请求(Master请求除外)
• 要在 Windows IoT 端解析有效的字符或字符串，Arduino 必须以有效的 ASCII 格式发送字节

我附上了基本的 Arduino Sketch 和 RPi2 UWP 代码:

Arduino Sketch(I2C Slave)响应主机请求的字节:

#include <Wire.h>
#define MyAddress 0x40

byte DataToBeSend[1];
byte ReceivedData;

void setup()
{
    /* Initialize I2C Slave & assign call-back function 'onReceive' on 'I2CReceived'*/
    Wire.begin(MyAddress);
    Wire.onReceive(I2CReceived);
    Wire.onRequest(I2CRequest);
}

void loop()
{
    /* Increment DataToBeSend every second and make sure it ranges between 0 and 99 */
    DataToBeSend[0] = (DataToBeSend[0] >= 99) ? 0 : DataToBeSend[0] + 1;
    delay(1000);
}

/* This function will automatically be called when RPi2 sends data to this I2C slave */
void I2CReceived(int NumberOfBytes)
{
    /* WinIoT have sent data byte; read it */
    ReceivedData = Wire.read();
}

/* This function will automatically be called when RPi2 requests for data from this I2C slave */
void I2CRequest()
{
    /*Send data to WinIoT */
    Wire.write(DataToBeSend,1);
}

Windows IoT UWP - I2C 主代码片段:

using System;
using Windows.Devices.Enumeration;
using Windows.Devices.I2c;

namespace Windows_10_I2C_Demo
{
    public class I2cHelper
    {
        private static string AQS;
        private static DeviceInformationCollection DIS;

        public static async System.Threading.Tasks.Task<byte> WriteRead_OneByte(byte ByteToBeSend)
        {
            byte[] ReceivedData = new byte[1];

            /* Arduino Nano's I2C SLAVE address */
            int SlaveAddress = 64;              // 0x40

            try
            {
                // Initialize I2C
                var Settings = new I2cConnectionSettings(SlaveAddress);
                Settings.BusSpeed = I2cBusSpeed.StandardMode;

                if (AQS == null || DIS == null)
                {
                    AQS = I2cDevice.GetDeviceSelector("I2C1");
                    DIS = await DeviceInformation.FindAllAsync(AQS);
                }


                using (I2cDevice Device = await I2cDevice.FromIdAsync(DIS[0].Id, Settings))
                {
                    /* Send byte to Arduino Nano */
                    Device.Write(new byte[] { ByteToBeSend });

                    /* Read byte from Arduino Nano */
                    Device.Read(ReceivedData);
                }
            }
            catch (Exception)
            {
                // SUPPRESS ANY ERROR
            }

            /* Return received data or ZERO on error */
            return ReceivedData[0];
        }
    }
}

如何使用上面的 Windows IoT UWP - I2C Master Code Snippet？

public async void TestFunction()
{
    byte DataToBeSend = 100;
    byte ReceivedData;
    ReceivedData = await I2cHelper.WriteRead_OneByte(DataToBeSend);
}

在深入了解之前，您应该对 I2C 通信有一个清晰的认识。引用以下文章以清楚了解 Arduino 之间的主从通信:http://www.instructables.com/id/I2C-between-Arduinos/?ALLSTEPS

要深入了解，请引用以下项目:
Arduino I2C communication with Raspi 2 WIOT
Windows IoT (RPi2) - I2C Accelerometer