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The Raspberry Pi's IO Functionality in an easy-to-use API for .NET (Mono/.NET Core). Our mission is to make .NET a first-class citizen in the Python-centric community of Raspberry Pi developers.

• Features
  • Peripherals
• Breaking changes
  • Version ≥ 0.18.0
• Installation
• Running the latest version of Mono
  • For Debian Stretch
• Running .NET Core 3.1
• Usage
  • Run the app on the raspberry
• Obtaining Board and System Information
• Using the GPIO Pins
  • Pin Information
  • Digital Read and Write
  • Hardware PWM
  • Software PWM
  • Tone Generation
  • Interrupts and Callbacks
• Using the SPI Bus
• I2C to connect ICs
• Timing and Threading
  • Timing
  • Threading
• Serial Ports (UART)
• The Camera Module
  • Capturing Images
  • Capturing Video
• Audio settings
• Handy Notes
• Related Projects and Nugets

This library enables developers to use the various Raspberry Pi's hardware modules:

• Pi.Camera Provides access to the official Raspberry Pi Camera module.
• Pi.Info Provides information on this Raspberry Pi's CPU and form factor.
• Pi.Gpio Provides access to the Raspberry Pi's GPIO as a collection of GPIO Pins.
• Pi.Spi Provides access to the 2-channel SPI bus.
• Pi.I2c Provides access to the functionality of the I2C bus.
• Pi.Timing Provides access to The PI's Timing and threading API.

We offer an additional package with helpful classes to use peripherals, many of them are from pull requests from our contributors. The current set of peripherals supported are:

• Infrared Sensor HX-1838
• Led Strip APA-102C
• NFC/RFID Controller MFRC-522
• DHT family digital relative humidity and temperature sensors:
  • DHT11
  • DHT12
  • DHT21 / AM-2301
  • DHT22 / AM-2302
• OLED Display SSD-1306
• Generic Button connected to GPIO
• GY-521 MPU6050 Accelerometer
• Ultrasonic Sensor HC-SR04
• ADS1015 and ADS1115 I2C Analog-to-Digital Converter devices

This version requires .NET core 3.0 to build and run.

In the beginning, RaspberryIO was built around WiringPi library and all our classes, properties, enums, etc. was based on those ones used in WiringPi too.

Now, we are working on a more general version of RaspberryIO (Abstractions) that, could use any core library (WiringPi, PiGpio or even new ones). So, it was necessary to change certain properties and enums for more general ones.

A breaking change in this new general version is the pinout numbering system. As we already explained above, RaspberryIO was using the WiringPi pinout numbering system, but now it uses theBCM pinout numbering system.

Note: The pin numbers are totally different in both systems, so we recommend you to double check carefully the physical pins where you connect any device.

Install basic Raspberry.IO package:

PM> Install-Package Unosquare.Raspberry.IO

If you want to implement your own provider for RaspberryIO, you must use the following package to implement all thePi providers:

PM> Install-Package Unosquare.WiringPi

Note: For now, we have fully implemented theWiringPi library and we are working in thePiGpio implementation.

Note: The latest development builds require .NET core 3.0 to build and run. You should upgrade to the latest Version of Visual Studio first.

Install Raspberry.IO Peripherals package (Optional):

PM> Install-Package Unosquare.RaspberryIO.Peripherals

It is recommended that you install the latest available release of Mono because what is available in the Raspbian repo is quite old (3.X). These commands were tested using Raspbian Stretch. The version of Mono that is installed at the time of this writing is:

Mono JIT compiler version 5.20.1.19 (tarball Thu Apr 11 19:13 UTC 2019)

The commands to get Mono installed are the following:

sudo apt install apt-transport-https dirmngr gnupg ca-certificatessudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EFecho "deb https://download.mono-project.com/repo/debian stable-raspbianstretch main" | sudo tee /etc/apt/sources.list.d/mono-official-stable.listsudo apt updatesudo apt-get install mono-complete

Now, verify your version of Mono by runningmono --version. Version 4.6 and above should be good enough.

This project can also run in .NET Core. To install .Net Core 3.1 sdk please execute the following commands:

$ sudo apt-get -y update$ sudo apt-get -y install libunwind8 gettext$ wget https://download.visualstudio.microsoft.com/download/pr/67766a96-eb8c-4cd2-bca4-ea63d2cc115c/7bf13840aa2ed88793b7315d5e0d74e6/dotnet-sdk-3.1.100-linux-arm.tar.gz$ sudo mkdir -p /usr/share/dotnet$ sudo tar -xvf dotnet-sdk-3.1.100-linux-arm.tar.gz -C /usr/share/dotnet$ sudo ln -s /usr/share/dotnet/dotnet /usr/bin/dotnet

If you want to install just the runtime, use the following commands:

$ sudo apt-get -y update$ sudo apt-get -y install libunwind8 gettext$ wget https://download.visualstudio.microsoft.com/download/pr/60d21925-7f8f-4004-9afe-aebd041d2d4a/0db2946738642d7f88f71f7800522e8c/dotnet-runtime-3.1.0-linux-arm.tar.gz$ sudo mkdir -p /usr/share/dotnet$ sudo tar -xvf dotnet-runtime-3.1.0-linux-arm.tar.gz -C /usr/share/dotnet$ sudo ln -s /usr/share/dotnet/dotnet /usr/bin/dotnet

Now, verify your version of .Net Core by runningdotnet --info.Visithttps://aka.ms/dotnet-download (orhttps://dotnet.microsoft.com/download/dotnet-core/3.1) to check for newer versions of the .Net Core runtime (or SDK). The Raspberry Pi running the default Raspbian OS needs the versions named "Linux ARM32".

Before start using RaspberryIO, you must initializePi class (bootstrapping process) with the valid Abstractions implementation, in order to letPi know what implementation is going to use:

Pi.Init<BootstrapWiringPi>();

Note: This sample code uses thewiringpi-dotnet implementation, you can use this implementation adding theUnosquare.WiringPi nuget package to your project.

• You need to publish the project and you can accomplish this by usingdotnet-sshdeploy but first, you must edit these properties inside the csproj file in order to establish an ssh connection with your raspberry

<SshDeployHost>172.16.17.54</SshDeployHost><SshDeployTargetPath>/home/pi/Playground</SshDeployTargetPath><SshDeployUsername>pi</SshDeployUsername><SshDeployPassword>raspberry</SshDeployPassword>

• Install dotnet-sshdeploy as a global tool by running

$ dotnet tool install -g dotnet-sshdeploy

• Executedotnet-sshdeploy push in the same folder where Unosquare.RaspberryIO.Playground.csproj resides and if everything executes correctly you should see an output like this:

SSH Deployment Tool [Version 0.3.1.0](c)2015 - 2017 Unosquare SA de CV. All Rights Reserved.For additional help, please visit https://github.com/unosquare/sshdeployDeploying...    Configuration   Debug    Framework       dotnetcore2.2    Source Path     C:\raspberryio\src\Unosquare.RaspberryIO.Playground\bin\Debug\dotnetcore2.2\publish    Excluded Files  .ready|.vshost.exe|.vshost.exe.config    Target Address  172.16.17.54:22    Username        pi    Target Path     /home/pi/Playground    Clean Target    NO    Pre Deployment      Post Deployment Connecting to host 172.16.17.54:22 via SSH.Connecting to host 172.16.17.54:22 via SFTP.    Target Path '/home/pi/Playground' does not exist. -- Will attempt to create.    Target Path '/home/pi/Playground' created successfully.    Cleaning Target Path '/home/pi/Playground'    Deploying 8 files.    Finished deployment in 1.25 seconds.Completed.

• The default TargetFramework isnet461but you can change this by either modifying the RuntimeIdentifier property inside the csproj file or supplying it as a parameter like thisdotnet-sshdeploy push -f netcoreapp2.2.More information about dotnet-sshdeploy seethis

Alternatively, you can use Visual Studio's Publish feature and a SCP (SSH Copy) application such as WinSCP or FileZilla. This uses the example project from this library:

• Right click on "Unosquare.RaspberryIO.Playground" and select "Publish..."
• Select the publish profile you want to use (debug or release) and click on "Publish" on the right.
• Wait for the project to build and note the output path
• Open WinSCP, ensure you can connect to your raspberry
• Navigate to the output folder noted above on your local computer
• Select "Commands -> Keep remote folder current", check the local and remote folder entries in the dialog and choose "In new Window" from the "Start" button.
• Answer "Yes" to start an initial synchronisation. WinSCP will now automatically update the files on your Pi whenever you click the "Publish" button in Visual Studio. Note though that just building willnot update the publish folder.

• Using Mono:

  First of all, you need to give permissions to run the project by running the next command on your target folder:

      ubuntu@ubuntu:~/publish$ sudo chmod u+x *

  Or you just can add theSshDeployExecutePermission tag in your project's csproj file:

      <SshDeployExecutePermission>true</SshDeployExecutePermission>

  Or use the appropriate command line argument:

      dotnet-sshdeploy push ... -x true

  Then you can run your project:

   ubuntu@ubuntu:~/publish$ ./Unosquare.RaspberryIO.Playground

• Using .Net Core

    ubuntu@ubuntu:~/publish$ dotnet Unosquare.RaspberryIO.Playground.dll

  or

    ubuntu@ubuntu:~/publish$ chmod +x Unosquare.RaspberryIO.Playground  ubuntu@ubuntu:~/publish$ ./Unosquare.RaspberryIO.Playground

  (the first line only needs to be executed once or after an update, since copying may not automatically set the execute bit)

  Note: Depending on the underlying library, you may need to use root user privileges to run the app.

RaspberryIO contains useful utilities to obtain information about the board it is running on. You can simply call thePi.Info.ToString() method to obtain a dump of all system properties as a singlestring, or you can use the individual properties such as Installed RAM, Processor Count, Raspberry Pi Version, Serial Number, etc. There's not a lot more to this.

Pin reference for the B plus (B+) - Header P1

The above diagram shows the pins of GPIO Header P1. There is an additional GPIO header on the Pi called P5.More info available here

In order to access the pins, usePi.Gpio. The pins can have multiple behaviors and fortunatelyPi.Gpio can be iterated, addressed by index, addressed by BCM pin number and provides the pins as publicly accessible properties.

Here is an example of addressing the pins in all the various ways:

publicstaticvoidTestLedBlinking(){// Get a reference to the pin you need to use.// Both methods below are equivalentvarblinkingPin=Pi.Gpio[17];blinkingPin=Pi.Gpio[BcmPin.Gpio17];// Configure the pin as an outputblinkingPin.PinMode=GpioPinDriveMode.Output;// perform writes to the pin by toggling the isOn variablevarisOn=false;for(vari=0;i<20;i++){isOn=!isOn;blinkingPin.Write(isOn);System.Threading.Thread.Sleep(500);}}

All pins have handy properties and methods that you can use to drive them. For example, you can examine theCapabilities property to find out which features are available on the pin. You can also use thePinMode property to get or set the operating mode of the pin. Please note that the value of thePinMode property is by default set toInput and it will return the last mode you set the property to.

It is very easy to read and write values to the pins. In general, it is a 2-step process.

• Set the pin mode
• Read or write the bit value

Reading the value of a pin example:

Pi.Gpio.Pin27.PinMode=GpioPinDriveMode.Input;// The below lines are reoughly equivalentvarisOn=Pi.Gpio.Pin27.Read();// Reads as a booleanvarpinValue=Pi.Gpio.Pin27.ReadValue();// Reads as a GpioPinValue

Writing to a pin example

Pi.Gpio.Pin27.PinMode=GpioPinDriveMode.Output;// The below lines are reoughly equivalentPi.Gpio.Pin27.Write(true);// Writes a booleanPi.Gpio.Pin27.Write(GpioPinValue.High);// Writes a pin value

Simple code for led dimming:

varpin=(GpioPin)Pi.Gpio[BcmPin.Gpio24];pin.PinMode=GpioPinDriveMode.PwmOutput;pin.PwmMode=PwmMode.Balanced;pin.PwmClockDivisor=2;while(true){for(varx=0;x<=100;x++){pin.PwmRegister=(int)pin.PwmRange/100*x;Thread.Sleep(10);}for(varx=0;x<=100;x++){pin.PwmRegister=(int)pin.PwmRange-((int)pin.PwmRange/100*x);Thread.Sleep(10);}}

PwmRange is the maximun value of the pulse width, than means 100% of pulse width. Changing this value allows you to have a more fine or coarse control of the pulse width (default 1024).

PwmRegister is the current pulse width. Changing this value allows you to change the current pulse width and thus the duty cycle.

Duty Cycle is equals toPwmRegister divide byPwmRange. Assuming aPwmRange value of 1024 (default), we have:

Note: Hardware PWM can be used only in GPIO12, GPIO13, GPIO18 and GPIO19.

Simple code for led dimming:

varrange=100;varpin=(GpioPin)Pi.Gpio[BcmPin.Gpio24];pin.PinMode=GpioPinDriveMode.Output;pin.StartSoftPwm(0,range);while(true){for(varx=0;x<=100;x++){pin.SoftPwmValue=range/100*x;Thread.Sleep(10);}for(varx=0;x<=100;x++){pin.SoftPwmValue=range-(range/100*x);Thread.Sleep(10);}}

SoftPwmRange is the range of the pulse width, than means 100% of pulse width (We notice better performance using a range value of 100).

SoftPwmValue is the current pulse width. Changing this value allows you to change the current pulse width and thus the duty cycle.

Note: Software PWM can be used in any GPIO.

You can emit tones by using SoftToneFrequency. Example:

// Get a reference to the pinvarpassiveBuzzer=(GpioPin)Pi.Gpio[BcmPin.Gpio24];// Set the frequency to Alto Do (523Hz)passiveBuzzer.SoftToneFrequency=523// Wait 1 secondSystem.Threading.Thread.Sleep(1000);// And stoppassiveBuzzer.SoftToneFrequency=0;

Register an Interrupt Callback example:

usingSystem;usingUnosquare.RaspberryIO;usingUnosquare.RaspberryIO.Gpio;classProgram{// Define the implementation of the delegate;staticvoidISRCallback(){Console.WriteLine("Pin Activated...");}staticvoidMain(string[]args){Console.WriteLine("Gpio Interrupts");varpin=Pi.Gpio.Pin24;pin.PinMode=GpioPinDriveMode.Input;pin.RegisterInterruptCallback(EdgeDetection.FallingEdge,ISRCallback);Console.ReadKey();}}

I really liked the following description fromNeil's Log Book:The SPI (Serial Peripheral Interface) protocol behaves like a ring buffer so that whenever the master sends a byte to the slave, the slave sends a byte back to the master. The slave can use this behavior to return a status byte, a response to a previous byte, or null data (the master may choose to read the returned byte or ignore it). The bus operates on a 4-wire interface.

RaspberryIO provides easy access to the 2 SPI channels available on the Raspberry. The functionality depends onWiring Pi's SPI library. Please note that you may need to issue the commandgpio load spi before starting your application (or as aSystem.Diagnostics.Process when your application starts) if the SPI kernel drivers have not been loaded.

In order to use an SPI channel youMUST always set theChannel0Frequency orChannel1Frequency (depending on the channel you want to use) before calling theSendReceive method. If the property is not set beforehand the SPI channel will fail initialization. See an example below:

Example of using the SPI Bus

Pi.Spi.Channel0Frequency=SpiChannel.MinFrequency;varrequest=System.Text.Encoding.ASCII.GetBytes("HELLO!");varresponse=Pi.Spi.Channel0.SendReceive(request);

Note: In order to enable the second SPI channel (SPI1) you need to adddtoverlay=spi1-1cs to the config file.

The Inter IC Bus (I2C) is a cousin of the SPI bus but it is somewhat more complex and it does not work as a ring buffer like the SPI bus. It also connects all of its slave devices in series and depends on 2 lines only. There is a nice tutorial on setting up and using the I2C bus atRobot Electronics. From their site:The physical bus is just two wires, called SCL and SDA. SCL is the clock line. It is used to synchronize all data transfers over the I2C bus. SDA is the data line. The SCL & SDA lines are connected to all devices on the I2C bus. There needs to be a third wire which is just the ground or 0 volts. There may also be a 5volt wire is power is being distributed to the devices. Both SCL and SDA lines are "open drain" drivers. What this means is that the chip can drive its output low, but it cannot drive it high. For the line to be able to go high you must provide pull-up resistors to the 5v supply. There should be a resistor from the SCL line to the 5v line and another from the SDA line to the 5v line. You only need one set of pull-up resistors for the whole I2C bus, not for each device.

RaspberryIO provides easy access to the I2C bus available on the Raspberry. Please note that you may need to issue the commandgpio load i2c before starting your application (or as aSystem.Diagnostics.Process when your application starts) if the I2C kernel drivers have not been loaded. The default baud rate is 100Kbps. If you wish to initialize the bus at a different baud rate you may issue, for example,gpio load i2c 200. This will load the bus at 200kbps.

In order to detect I2C devices, you could use thei2cdetect system command. Just remember that on a Rev 1 Raspberry Pi it's device 0, and on a Rev. 2 it's device 1. e.g.

i2cdetect -y 0 # Rev 1i2cdetect -y 1 # Rev 2

Example of using the I2C Bus:

// Register a device on the busvarmyDevice=Pi.I2C.AddDevice(0x20);// Simple Write and Read (there are algo register read and write methods)myDevice.Write(0x44);varresponse=myDevice.Read();// List registered devices on the I2C Busforeach(vardeviceinPi.I2C.Devices){Console.WriteLine($"Registered I2C Device:{device.DeviceId}");}

System calls to provide various timing and sleeping functions.

Getting the number of microseconds or milliseconds since system boot:

// Getting the number of microseconds since system boot.varmicros=Pi.Timing.Microseconds;// Getting the number of milliseconds since system boot.varmillis=Pi.Timing.Milliseconds;

Pausing program execution for a certain number of microseconds or milliseconds.

// Pausing program execution for 50 microseconds.Pi.Timing.SleepMicroseconds(50);// Pausing program execution for 100 milliseconds.Pi.Timing.SleepMilliseconds(100);

Allows the creation of a thread which is another function in your program that runs concurrently with your main program. An example may be to have this function wait for an interrupt while your program carries on doing other tasks. The thread can indicate an event, or action by using global variables to communicate back to the main program, or other threads.

Basic thread creation:

staticvoidMain(){        ...Pi.Threading.StartThread(ThreadWorker);        ...}privatevoidThreadWorker(){// Thread body}

Passing data to a thread:

staticvoidMain(){        ...var threadName="Thread 1";varnamePointer=(IntPtr)Marshal.StringToHGlobalAnsi(threadName);varthreadHandle=Pi.Threading.StartThreadEx(ThreadWorker,namePointer);        ...Pi.Threading.StopThreadEx(threadHandle);        ...}privatevoidThreadWorker(IntPtrstate){varthreadName=Marshal.PtrToStringAnsi(state);// Thread body}

Note: Not all underlying libraries support all methods for creating threads. WiringPi, for example, does only support basic thread creation.

Where is the serial port API? Well, it is something we will most likely add in the future. For now, you can simply use the built-inSerialPort class the .NET framework provides.

ThePi.Camera module usesraspivid andraspistill to access the camera so they must be installed in order for your program to work properly.raspistill arguments are specified in an instance of theCameraStillSettings class, while theraspivid arguments are specified in an instance of theCameraVideoSettings class.

ThePi.Camera.CaptureImage* methods simply return an array of bytes containing the captured image. There are synchronous and asynchronous flavors of these methods so you can use the familiarasync andawait pattern to capture your images. Allraspistill arguments (except for those that control user interaction such as-k) are available via theCameraStillSettings. To start, create a new instance of theCameraStillSettings class and pass it on to your choice of thePi.Camera.CaptureImage* methods. There are shortcut methods available that simply take a JPEG image at the given Width and Height. By default, the shortcut methods set the JPEG quality at 90%.

Example using a shortcut method:

staticvoidTestCaptureImage(){varpictureBytes=Pi.Camera.CaptureImageJpeg(640,480);vartargetPath="/home/pi/picture.jpg";if(File.Exists(targetPath))File.Delete(targetPath);File.WriteAllBytes(targetPath,pictureBytes);Console.WriteLine($"Took picture -- Byte count:{pictureBytes.Length}");}

Example using a CaptureImage method:

staticbyte[]TestCaptureImage(){varsettings=newCameraStillSettings{CaptureWidth=640,CaptureHeight=480,CaptureJpegQuality=90,CaptureTimeoutMilliseconds=300};returnCaptureImage(settings);}

Capturing video streams is somewhat different but it is still very easy to do. The concept behind it is toOpen a video stream providing your own callback. When opening the streamRaspberry IO will spawn a separate thread and will not block the execution of your code, but it will continually call your callback method containing the bytes that are being read from the camera until theClose method is called or until the timeout is reached.

Example of capturing a stream of H.264 video

staticvoidTestCaptureVideo(){// Setup our working variablesvarvideoByteCount=0;varvideoEventCount=0;varstartTime=DateTime.UtcNow;// Configure video settingsvarvideoSettings=newCameraVideoSettings(){CaptureTimeoutMilliseconds=0,CaptureDisplayPreview=false,ImageFlipVertically=true,CaptureExposure=CameraExposureMode.Night,CaptureWidth=1920,CaptureHeight=1080};try{// Start the video recordingPi.Camera.OpenVideoStream(videoSettings,onDataCallback:(data)=>{videoByteCount+=data.Length;videoEventCount++;},onExitCallback:null);// Wait for user interactionstartTime=DateTime.UtcNow;Console.WriteLine("Press any key to stop reading the video stream . . .");Console.ReadKey(true);}catch(Exceptionex){Console.WriteLine($"{ex.GetType()}:{ex.Message}");}finally{// Always close the video stream to ensure raspivid quitsPi.Camera.CloseVideoStream();// Output the statsvarmegaBytesReceived=(videoByteCount/(1024f*1024f)).ToString("0.000");varrecordedSeconds=DateTime.UtcNow.Subtract(startTime).TotalSeconds.ToString("0.000");Console.WriteLine($"Capture Stopped. Received{megaBytesReceived} Mbytes in{videoEventCount} callbacks in{recordedSeconds} seconds");}}

Basic audio settings have been implemented in RaspberryIO:

• Set a specific volume level percentage.
• Set a specific volume level in decibels (dB)
• Mute an audio device.
• Consult audio device settings.

Users set an audio card, an audio device and an audio command to perform an audio action. Example of audio tasks:

awaitPi.PiVolumeControl.SetVolumePercentage(85);awaitPi.PiVolumeControl.SetVolumeByDecibels(-1.00f);

The code above sets the volume level in two different formats: Percentage or Decibels.The first method sets the volume on percentage (0% - 100%) and the second sets the volume level on decibels(dB) (-101.32dB - 4.00dB).

Users can consult the current audio settings by using the method GetState.An example is shown below:

varcurrentState=awaitPi.Audio.GetState();Console.WriteLine(currentState);

The same result can be achieved by setting the volume level to 0% or -9999.99dB.

In order to setup Wi-Fi, run:sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

A good file should look like this:

country=USctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdevupdate_config=1network={    ssid="your_real_wifi_ssid"    scan_ssid=1    psk="your_real_password"}

And then restart the services as follows:

sudo systemctl daemon-reloadsudo systemctl restart dhcpcd

You can also configure most boot options by running:sudo raspi-config