nanoFramework.Iot.Device.Bmm150 1.2.590

Bmm150 - 磁力计

Bmm150 是一个磁力计，可通过 I2C 或 SPI 进行控制。此实现已在 ESP32 平台上进行了测试，具体是在 M5Stack Grey 上。

文档

Bmm150 的文档可以在 这里找到

用法

重要：在创建 I2cDevice 之前，请确保适当地设置了 I2C 引脚，特别是对于 ESP32，确保已安装 nanoFramework.Hardware.ESP32 nuget。

//////////////////////////////////////////////////////////////////////
// when connecting to an ESP32 device, need to configure the I2C GPIOs
// used for the bus
Configuration.SetPinFunction(21, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(22, DeviceFunction.I2C1_CLOCK);

对于其他设备如 STM32，请确保您正在使用您要使用的 I2C 总线的预置引脚。

您可以在 示例 目录中找到一个示例。用法简单，包括校准的可能性。

// The I2C pins 21 and 22 in the sample below are ESP32 specific and may differ from other platforms.
// Please double check your device datasheet.
Configuration.SetPinFunction(22, DeviceFunction.I2C1_CLOCK);
Configuration.SetPinFunction(21, DeviceFunction.I2C1_DATA);

I2cConnectionSettings mpui2CConnectionSettingmpus = new(1, Bmm150.DefaultI2cAddress);

using Bmm150 bmm150 = new Bmm150(I2cDevice.Create(mpui2CConnectionSettingmpus));

Debug.WriteLine($"Please move your device in all directions...");

bmm150.CalibrateMagnetometer();

Debug.WriteLine($"Calibration completed.");

while (true)
{
    Vector3 magne = bmm150.ReadMagnetometer(true, TimeSpan.FromMilliseconds(11));

    var head_dir = Math.Atan2(magne.X, magne.Y) * 180.0 / Math.PI;

    Debug.WriteLine($"Mag data: X={magne.X,15}, Y={magne.Y,15}, Z={magne.Z,15}, head_dir: {head_dir}");

    Thread.Sleep(100);
}

预期输出

Please move your device in all directions...
Calibration completed.
Mag data: X=    32.97089767, Y=   -10.99029922, Z=   -27.41439819, head_dir: 108.43494945
Mag data: X=    38.83239364, Y=   -10.62395668, Z=    -22.2116661, head_dir: 105.30084201
Mag data: X=    43.96039581, Y=     -8.4257431, Z=     4.60182046, head_dir: 100.85010634
Mag data: X=    42.49582672, Y=   -8.059553146, Z=   9.0047292709, head_dir: 100.7388972
Mag data: X=    42.86371994, Y=    -12.8224802, Z=     8.20643711, head_dir: 106.65430547
Mag data: X=    36.26864242, Y=    -6.22794914, Z=   -21.41402244, head_dir: 99.74364301
Mag data: X=    29.30693054, Y=    -9.89108943, Z=   -32.21274185, head_dir: 108.6495335
Mag data: X=    15.75333309, Y=    -8.42620182, Z=  -37.029045104, head_dir: 118.14159082
Mag data: X=      4.7626357, Y=    -6.22806167, Z=   -42.23312759, head_dir: 142.59463794
Mag data: X=    -4.39627885, Y=    -6.59441852, Z=   -36.22841644, head_dir: -146.309933
Mag data: X=   -10.25779819, Y=    -5.12889909, Z=   -38.62528991, head_dir: -116.56504656
Mag data: X=  -19.050889968, Y=     0.73272651, Z=  -37.033847808, head_dir: -87.7974031
Mag data: X=   -35.90294647, Y=     1.46542632, Z=   -18.61460113, head_dir: -87.66269127
Mag data: X=   -37.73472976, Y=     8.42620182, Z=   -13.41051959, head_dir: -77.41230537
Mag data: X=   -37.73472976, Y=     9.52527141, Z=   -12.20957756, head_dir: -75.83294707
Mag data: X=   -18.31749725, Y=     0.73269987, Z=   -31.42057418, head_dir: -87.70938928
Mag data: X=    -2.19813942, Y=    -7.69348812, Z=  -37.029045104, head_dir: -164.054600542

校准

您可以通过CalibrateMagnetometer函数获得访问并执行校准，该函数将...注意，校准需要几秒钟。

bmm150.CalibrateMagnetometer();

如果不进行校准，您将得到一个类似以下的数据云

进行正确的校准时，需要在执行校准的过程中将传感器移动到所有可能的方向。您应该考虑使用足够的样本运行，至少几百个。默认设置为100。在远离任何磁场的所有方向移动传感器时，您将得到上述云。从这些云中计算平均值并将其从读取值中减去，将得到像这样居中的数据云

要创建这些点云图，每个云是X-Y、Y-Z和Z-X的坐标。

校准完成一次后，您将能够使用带有偏差校正的ReadMagnetometer函数读取数据。您仍然可以使用ReadMagnetometerWithoutCalibration函数读取未经校准的数据。

Bmm150不支持/未实现的功能

• 设备自检
• 设备复位
• 切换操作模式（默认为正常模式）

测试

单元测试项目位于\Bmm150.tests。您可以使用VS2019内置的测试功能，如下所示

[TestMethod]
public void TestCompensateVector3()
{
        uint rhall = 42;
        Vector3 rawMagnetormeterData = new Vector3 { X = 13.91375923, Y = -28.74289894, Z = 10.16711997 };
        Bmm150TrimRegisterData trimRegisterData = new Bmm150TrimRegisterData()
        {
            DigX1 = 0,
            DigX2 = 26,
            DigXy1 = 29,
            DigXy2 = -3,
            DigXyz1 = 7053,
            DigY1 = 0,
            DigY2 = 26,
            DigZ1 = 24747,
            DigZ2 = 763,
            DigZ3 = 0,
            DigZ4 = 0
        };

        double x = Bmm150Compensation.CompensateX(rawMagnetormeterData.X, rhall, trimRegisterData);
        double y = Bmm150Compensation.CompensateY(rawMagnetormeterData.Y, rhall, trimRegisterData);
        double z = Bmm150Compensation.CompensateZ(rawMagnetormeterData.Z, rhall, trimRegisterData);

        // Calculated value should be: -1549.91882323
        Assert.Equal(Math.Ceiling(x), Math.Ceiling(-1549.918823), "Unexpected x-axis value.");

        // Calculated value should be: 3201.80615234
        Assert.Equal(Math.Ceiling(y), Math.Ceiling(3201.80615234), "Unexpected y-axis value.");

        // Calculated value should be: 26.20077896
        Assert.Equal(Math.Ceiling(z), Math.Ceiling(26.20077896), "Unexpected z-axis value.");
}

备注

• BMI160嵌入BMM150。