소개

RaspberryPi가 얻은 값을 HoloLens에 보내고 싶었기 때문에 RaspberryPi에 Windows 10 IoT Core를 도입했습니다.
따라서 UWP 앱에서 RaspberryPi를 실행하고 연결된 모듈에서 값을 가져 와서 GUI로 표시합니다.

환경

Raspberry Pi 3 Model B(OS: Windows 10 IoT core ver10.0.17134.1)

MPU6050 (가속도 센서)

VisualStudio2017

절차

MPU6050의 데이터 시트를 보면서 취득하고 싶은 데이터 레지스터의 주소를 지정합니다.
결과 값을 GUI의 텍스트에 반영합니다.

MPU6050 데이터시트 ↓↓↓
htps //w w. 응 ㄔ 센센세. 이 m/wp-콘텐 t/우 pぉ아ds/2015/02/M푸-6000-다시에 t1. pdf

소스 코드

cs에서만 xaml을 생략합니다.

ReadValuesByRaspberryPi.cpp

using System;
using System.Diagnostics;
using System.Threading;
using Windows.UI.Xaml.Controls;
using Windows.Devices.Enumeration;
using Windows.Devices.I2c;

namespace ReadValuesByRaspberryPi
{
    struct Acceleration
    {
        public int X;
        public int Y;
        public int Z;
    };

    /// <summary>
    /// app that reads data over I2C from an attached MPU6050 accelerometer
    /// </summary>
    public sealed partial class MainPage : Page
    {
        private const byte I2C_ADDR = 0x68;                 /* Address of MP6050 */
        private const byte POWER_CONTROL = 0x6B;            /* Address of the Power Control register */
        private const byte ACCEL_REG_X = 0x3B;              /* Address of the X Axis data register */
        private const byte ACCEL_REG_Y = 0x3D;              /* Address of the Y Axis data register */
        private const byte ACCEL_REG_Z = 0x3F;              /* Address of the Z Axis data register */

        private I2cDevice MPU6050; //Module name
        private Timer periodicTimer;

        private int cnt;

        public MainPage()
        {
            this.InitializeComponent();

            /* Register for the unloaded event so we can clean up upon exit */
            Unloaded += MainPage_Unloaded;

            /* Initialize the I2C bus, accelerometer, and timer */
            InitI2CAccel();
        }

        private async void InitI2CAccel()
        {

            var settings = new I2cConnectionSettings(I2C_ADDR); 
            settings.BusSpeed = I2cBusSpeed.FastMode;
            var controller = await I2cController.GetDefaultAsync();
            MPU6050 = controller.GetDevice(settings);    /* Create an I2cDevice with our selected bus controller and I2C settings */


            /* 
             * Initialize the accelerometer:
             *
             * For this device, we create 2-byte write buffers:
             * The first byte is the register address we want to write to.
             * The second byte is the contents that we want to write to the register. 
             */
            byte[] WriteBuf_PowerControl = new byte[] { POWER_CONTROL, 0x20 };    /* puts the accelerometer into measurement mode */

            /* Write the register settings */
            try
            {
                MPU6050.Write(WriteBuf_PowerControl);
            }
            /* If the write fails display the error and stop running */
            catch (Exception ex)
            {
                Text_Status.Text = "Failed to communicate with device: " + ex.Message;
                return;
            }

            /* Now that everything is initialized, create a timer so we read data every 100mS */
            periodicTimer = new Timer(this.TimerCallback, null, 0, 100);
        }

        private void MainPage_Unloaded(object sender, object args)
        {
            /* Cleanup */
            MPU6050.Dispose();
        }

        private void TimerCallback(object state)
        {
            string xText, yText, zText;
            string statusText;

            /* Read and format accelerometer data */
            try
            {
                Acceleration accel = ReadI2CAccel();
                xText = String.Format("X Axis: {0}", accel.X);
                yText = String.Format("Y Axis: {0}", accel.Y);
                zText = String.Format("Z Axis: {0}", accel.Z);
                statusText = "Status: Running";
            }
            catch (Exception ex)
            {
                xText = "X Axis: Error";
                yText = "Y Axis: Error";
                zText = "Z Axis: Error";
                statusText = "Failed to read from Accelerometer: " + ex.Message;
            }

            /* UI updates must be invoked on the UI thread */
            var task = this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
                Text_X_Axis.Text = xText;
                Text_Y_Axis.Text = yText;
                Text_Z_Axis.Text = zText;
                Text_Status.Text = statusText;
                //Debug.Write(xText + "\n");
            });
        }

        // Write the address then read data from accelerometer
        private Acceleration ReadI2CAccel()
        {
            byte[] RegAddrBuf_X = new byte[] { ACCEL_REG_X }; /* Register address we want to read from */
            byte[] RegAddrBuf_Y = new byte[] { ACCEL_REG_Y };
            byte[] RegAddrBuf_Z = new byte[] { ACCEL_REG_Z };

            byte[] ReadBuf_X = new byte[1];                   /* We read 3 bytes sequentially to get all 3 two-byte axes registers */
            byte[] ReadBuf_Y = new byte[1];
            byte[] ReadBuf_Z = new byte[1];

            /* 
             * Read from the accelerometer 
             * We call WriteRead() so we write the address of the each-Axis I2C register, then read each axes
             */
            MPU6050.WriteRead(RegAddrBuf_X, ReadBuf_X); //
            MPU6050.WriteRead(RegAddrBuf_Y, ReadBuf_Y);
            MPU6050.WriteRead(RegAddrBuf_Z, ReadBuf_Z);

            cnt++;
            Debug.Write(ReadBuf_X[0] + "\n");

            Acceleration accel;
            accel.X = ReadBuf_X[0];
            accel.Y = ReadBuf_Y[0];
            accel.Z = ReadBuf_Z[0];

            return accel;
        }
    }
}

실행 결과

Raspberry Pi 측의 출력 화면 (수시로 갱신됩니다)

확실히 값은 잡히고 있군요.

문제점

왠지 값이 갱신되는데 800ms 정도의 간격이 비어 버린다.
또 조사해 해결할 수 있으면 갱신합니다.