SetupHelpers.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Threading;
using System.Runtime.InteropServices;
using System.Device.Spi;
using System.Device.I2c;
using System.Device.Pwm;
using System.Device.Pwm.Drivers;
using Iot.Device.Adc;
using Iot.Device.Bmxx80;
using Iot.Device.Bmxx80.PowerMode;
using Xunit;

namespace System.Device.Gpio.Tests;

public static class SetupHelpers
{
    public const int MinAdc = 0;
    public const int MaxAdc = 1023;
    public const int HalfAdc = MaxAdc / 2;
    private const int Bme280I2cBusId = 1;

    public static void AdcValueAround(int expected, int actual, int error = 50)
    {
        Assert.InRange(
            actual,
            Math.Max(MinAdc, expected - error),
            Math.Min(MaxAdc, expected + error));
    }

    public static void DutyCycleAround(double expected, double actual, double error = 0.01)
    {
        Assert.InRange(
            actual,
            Math.Max(0, expected - error),
            Math.Min(1, expected + error));
    }

    public static Mcp3008 CreateAdc()
    {
        return new Mcp3008(SpiDevice.Create(new SpiConnectionSettings(0, 0)));
    }

    public static Bme280 CreateBme280()
    {
        var settings = new I2cConnectionSettings(Bme280I2cBusId, Bme280.DefaultI2cAddress);
        var bme280 = new Bme280(I2cDevice.Create(settings));
        SetupBme280(bme280);
        return bme280;
    }

    public static I2cBus CreateI2cBusForBme280()
    {
        return I2cBus.Create(Bme280I2cBusId);
    }

    public static Bme280 CreateBme280(I2cBus i2cBus)
    {
        var bme280 = new Bme280(i2cBus.CreateDevice(Bme280.DefaultI2cAddress));
        SetupBme280(bme280);
        return bme280;
    }

    private static void SetupBme280(Bme280 bme280)
    {
        // https://github.com/dotnet/iot/issues/753
        bme280.SetPowerMode(Bmx280PowerMode.Normal);
        Thread.Sleep(100);
    }

    private static PwmChannel CreatePwmChannelCore(int frequency, double dutyCycle)
    {
        try
        {
            return PwmChannel.Create(0, 0, frequency, dutyCycle);
        }
        catch (ArgumentException) when (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
        {
            // PWM is likely not enabled
            // Let's try to run against software PWM implementation
            return new SoftwarePwmChannel(18, frequency, dutyCycle, usePrecisionTimer: true);
        }
    }

    public static PwmChannel CreatePwmChannel(int frequency = 10000, bool stopped = false, double dutyCycle = 0.5)
    {
        var pwm = CreatePwmChannelCore(frequency, dutyCycle);

        if (!stopped)
        {
            pwm.Start();
        }

        return pwm;
    }
}