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fredeilkrwq
fredeil
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krwq
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HC-SR04 device binding (#153)
* Initial commit * Remove tests add GetDistance * Add sample * Update sample * Ref perform both operations at once * Fix some review * Update code to resemble krwq * Clean up the readmes * Add fritzing diagram * Add 1kohm resistor * Fix class docs
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‎src/devices/HCSR04/HCSR04.cs

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// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System;
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using System.Diagnostics;
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using System.Device.Gpio;
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using System.Device.I2c;
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using System.Device.I2c.Drivers;
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using System.Device.Spi;
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using System.Device.Spi.Drivers;
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using System.Threading;
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namespace Iot.Device.HCSR04
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{
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public class Sonar : IDisposable
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{
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private readonly int _echo;
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private readonly int _trigger;
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private GpioController _controller;
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private Stopwatch _timer = new Stopwatch();
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/// <summary>
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/// Creates a new instance of the HC-SCR04 sonar.
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/// </summary>
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/// <param name="triggerPin">Trigger pulse input.</param>
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/// <param name="echoPin">Trigger pulse output.</param>
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public Sonar(int triggerPin, int echoPin)
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{
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_echo = echoPin;
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_trigger = triggerPin;
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_controller = new GpioController();
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_controller.OpenPin(_echo, PinMode.Input);
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_controller.OpenPin(_trigger, PinMode.Output);
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_controller.Write(_trigger, PinValue.Low);
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}
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/// <summary>
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/// Gets the current distance in cm.
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/// </summary>
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public double GetDistance()
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{
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_timer.Reset();
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// Trigger input for 10uS to start ranging
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// ref https://components101.com/sites/default/files/component_datasheet/HCSR04%20Datasheet.pdf
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_controller.Write(_trigger, PinValue.High);
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Thread.Sleep(TimeSpan.FromMilliseconds(0.01));
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_controller.Write(_trigger, PinValue.Low);
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_timer.Start();
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while(_controller.Read(_echo) == PinValue.Low)
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{
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}
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while(_controller.Read(_echo) == PinValue.High)
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{
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}
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_timer.Stop();
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TimeSpan elapsed = _timer.Elapsed;
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// distance = (time / 2) × velocity of sound (34300 cm/s)
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return (double)(elapsed.TotalMilliseconds * 34.3) / 2 - 8;
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}
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public void Dispose()
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{
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if(_controller != null)
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{
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_controller.Dispose();
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_controller = null;
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}
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}
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}
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}

‎src/devices/HCSR04/HCSR04.csproj

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<TargetFramework>netcoreapp2.1</TargetFramework>
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<EnableDefaultItems>false</EnableDefaultItems>
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</PropertyGroup>
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<ItemGroup>
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<PackageReference Include="System.Device.Gpio" Version="0.1.0-prerelease*" />
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<Compile Include="HCSR04.cs" />
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<None Include="README.md" />
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</ItemGroup>
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</Project>

‎src/devices/HCSR04/README.md

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# HC-SR04
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Device bindings for the HC-SR04 sonar distance sensor.
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## Summary
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Calculates the distance from an object by using the HC-SR04 distance sensor.
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## Binding Notes
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Provide any specifics related to binding API. This could include how to configure component for particular functions and example code.
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## References
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* [HC-SR04 data sheet](https://components101.com/sites/default/files/component_datasheet/HCSR04%20Datasheet.pdf)

‎src/devices/HCSR04/samples/HCSR04.Sample.cs

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// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System;
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using System.Device.Gpio;
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using System.Device.I2c;
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using System.Device.I2c.Drivers;
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using System.Device.Spi;
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using System.Device.Spi.Drivers;
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using System.Threading;
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using Iot.Device.HCSR04;
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namespace Iot.Device.HCSR04.Samples
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{
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class Program
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{
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static void Main(string[] args)
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{
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Console.WriteLine("Hello HCSR04 Sample!");
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using(var sonar = new Iot.Device.HCSR04.Sonar(4, 17))
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{
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while(true)
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{
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Console.WriteLine($"Value = {sonar.GetDistance()}");
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System.Threading.Thread.Sleep(100);
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}
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}
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}
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}
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}

‎src/devices/HCSR04/samples/HCSR04.Samples.csproj

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>netcoreapp2.1</TargetFramework>
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</PropertyGroup>
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<ItemGroup>
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<ProjectReference Include="../HCSR04.csproj" />
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<PackageReference Include="System.Device.Gpio" Version="0.1.0-prerelease*" />
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</ItemGroup>
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</Project>

‎src/devices/HCSR04/samples/README.md

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# Distance sensor sample (using HC-SR04)
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This simple example shows how to use the HC-SR04 device binding with dotnet/iot.
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## Breadboard layout
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The following fritz diagram depicts how you should wire your RPi in order to run the program, the resistance for R1 is 1kOhm.
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![Fritz diagram](raspberry_hc-sr04.png)

‎src/devices/HCSR04/samples/raspberry_hc-sr04.png

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