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Posted 1 Feb 2018
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IoT Starter Raspberry Pi Lumi

, 1 Feb 2018
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IoT.Starter.Pi.Thing growing into an embryo of a universal IR remote control.


This series, targeted to Raspberry Pi with Linux, started with IoT.Starter.Pi.Core using API First Design strategy to develop an ASP.NET Core Web Server automatically generated by Swagger Hub.

The second part introduced IoT.Starter.Pi.Thing, an embryo for Home Intelligence using Raspberry Pi with Linux. Designed as a starter kit for IoT initiatives, it provides a solid and structured platform to speed up product development. The starter kit concept encourages the teams to start working immediately on the product development.

The third part is IoT.Starter.Pi.Lirc, dedicated to IoT projects that require infrared devices. A test environment is created by a Console powered by Lirc, the Linux Infrared Remote Control. It is now time to benefit from what we learned from these tests.

At this complement of the third part, the objective is to extend the Thing web service to allow IR remotes and their respective codes to be considered by the API. Powered by Lirc, the IoT.Starter.Pi.Lumi is useful on IoT initiatives that require infrared support.

There will be then two Things, available as IoT starter kits:

API first

Following the API first strategy, a new API version 1.0.2 is created and summarized below, adding a RemoteApi controller to the existing specification. The GET operations should identify remotes and their respective IR codes. The POST operation reflects the intention to fire IR blasts for remotes already installed at RPI host, using Lirc software.

Generate RemoteApi

After we changed the swagger file to Version 1.0.2, SwaggerHub generated automatically the RemoteApi controller code. Do you remember "Upgrading the API"? It was explained at IoT.Starter.Pi.Core, please take a look there if you have any doubts.

Then, the generated code was tweaked to fit the objective, resulting on the following four operations:

public class RemoteApiController : Controller
    /// <summary>
    /// </summary>
    /// <remarks>returns ir code from remote</remarks>
    /// <param name="remote">Lirc remote</param>
    /// <param name="code">ir code</param>
    /// <response code="200">All the codes</response>
    [SwaggerResponse(200, typeof(List<string>), "All the codes")]
    public virtual IActionResult GetRemoteCode([FromRoute]string remote, [FromRoute]string code)
        string example = ("/usr/bin/irsend list " + remote + " " + code).Bash();

        return new ObjectResult(example);

    /// <summary>
    /// </summary>
    /// <remarks>returns all ir codes from remote</remarks>
    /// <param name="remote">Lirc remote</param>
    /// <response code="200">All the codes</response>
    [SwaggerResponse(200, typeof(List<string>), "All the codes")]
    public virtual IActionResult GetRemoteCodes([FromRoute]string remote)
        string example = (@"/usr/bin/irsend list " + remote + @" """"").Bash();

        return new ObjectResult(example);

    /// <summary>
    /// </summary>
    /// <remarks>returns all installed remotes</remarks>
    /// <param name="skip">number of records to skip</param>
    /// <param name="limit">max number of records to return</param>
    /// <response code="200">All the installed remotes</response>
    [SwaggerResponse(200, typeof(List<string>), "All the installed remotes")]
    public virtual IActionResult GetRemotes([FromQuery]int? skip, [FromQuery]int? limit)
        string example = (@"/usr/bin/irsend list """" """"").Bash();

        return new ObjectResult(example);

    /// <summary>
    /// </summary>
    /// <remarks>flashes ir code simulating the remote control</remarks>
    /// <param name="remote">Lirc remote</param>
    /// <param name="code">ir code</param>
    /// <response code="200">response</response>
    [SwaggerResponse(200, typeof(ApiResponse), "response")]
    public virtual IActionResult SendRemoteCode([FromRoute]string remote, [FromRoute]string code)
        string example = (@"/usr/bin/irsend send_once " + remote + " " + code).Bash();

        return new ObjectResult(example);

You can notice that irsend command is used at all them! The HttpGet operations identify IR remotes and their respective codes. For example, to list all installed remotes, the following command should be issued by Bash at host:

pi@lumi:~ $ irsend list "" ""

The equivalent code is shown below:

public virtual IActionResult GetRemotes([FromQuery]int? skip, [FromQuery]int? limit)
    string example = (@"/usr/bin/irsend list """" """"").Bash();

    return new ObjectResult(example);

The HttpPost operation has remote and code parameters, in order to properly blast IR codes through the output IR led. In this case, the irsend command at RPI host would be:

pi@lumi:~ $ irsend SEND_ONCE LED_44_KEY CYAN

The SendRemoteCode shows the equivalent below:

public virtual IActionResult SendRemoteCode([FromRoute]string remote, [FromRoute]string code)
    string example = (@"/usr/bin/irsend send_once " + remote + " " + code).Bash();

    return new ObjectResult(example);

As already shown at Lirc-Console, the ShellHelper posted by does the dirty work, starting a bash process, capturing the answer, and returning the string result.

public static class ShellHelper
    public static string Bash(this string cmd)
        var escapedArgs = cmd.Replace("\"", "\\\"");

        var process = new Process()
            StartInfo = new ProcessStartInfo
                FileName = "/bin/bash",
                Arguments = $"-c \"{escapedArgs}\"",
                RedirectStandardOutput = true,
                UseShellExecute = false,
                CreateNoWindow = true,
        string result = process.StandardOutput.ReadToEnd();
        return result;

home-web-ir powered by Lirc

In order to add Lirc support to the project, we apply the same strategy used before, installing Lirc before building the web service. The changes done at dockerfile and docker-compose are listed below.


The lirc-web.dockerfile shown below use the dotnet:2.0.0-runtime-stretch-arm32v7 image as base. Before installing Lirc, the OS is updated and upgraded. After Lirc package installation, the RPI configuration is copied to container, assuring that remotes installed at RPI host will be seen. The /boot/config.txt and /etc/lirc/lirc_options.conf are updated and remote config files are moved to /etc/lirc/lircd.conf.d, in order to keep the same setup installed at RPI host.

FROM microsoft/dotnet:2.0.0-runtime-stretch-arm32v7 AS base
ENV ASPNETCORE_URLS "http://*:5010"

  apt-get update \
  && apt-get upgrade -y \
  && apt-get install -y \
       lirc \
  --no-install-recommends && \
  rm -rf /var/lib/apt/lists/*

  mkdir -p /var/run/lirc \
  && rm -f /etc/lirc/lircd.conf.d/devinput.*

COPY Lirc/setup/config.txt /boot/config.txt
COPY Lirc/setup/lirc_options.conf /etc/lirc/lirc_options.conf 
COPY Lirc/setup/ir-remote.conf /etc/modprobe.d/ir-remote.conf
COPY Lirc/remotes /etc/lirc/lircd.conf.d

FROM microsoft/dotnet:2.0-sdk AS build
ENV ASPNETCORE_URLS "http://*:5010"
COPY *.sln ./
COPY *.dcproj ./
COPY src/IO.Swagger/IO.Swagger.csproj src/IO.Swagger/
RUN dotnet restore src/IO.Swagger/
COPY . .
WORKDIR /src/src/IO.Swagger
RUN dotnet build -c Release -r linux-arm -o /app

FROM build AS publish
RUN dotnet publish -c Release -r linux-arm -o /app

FROM base AS final
COPY --from=publish /app .
ENTRYPOINT ["dotnet", "IO.Swagger.dll"]

Then, same build used at IoT.Starter.Pi.Thing completes the home-web-ir building.


The io.swagger service was the only change at lirc-compose.yml, as shown below. The image for web service powered by Lirc changed to home-web-ir, to differentiate from previous home-web with no Lirc support.

    container_name: home-web-ir
    image: josemottalopes/home-web-ir
      context: .
      dockerfile: Lirc/lirc-web.Dockerfile
    - "5010"
    network_mode: bridge
    privileged: true
    restart: always
    - /var/run/lirc:/var/run/lirc

A docker volume is created at /var/run/lirc, insuring proper communication between containers running irsendcommands and Lirc output socket installed at RPI host. Since the other services from IoT.Starter.Pi.Thing are the same, home-web to home-web-ir is the only change from IoT.Starter.Pi.Thing to IoT.Starter.Pi.Lumi.

Running at RPI

Before running the tests, please note that Lirc should be properly installed and configured according to RPI Setup instructions. Following is the command to download and run home-web-ir, including docker volume configuration:

docker run --privileged -p 5010:5010 -d -it --name=home-web-ir -v /var/run/lirc:/var/run/lirc josemottalopes/home-web-ir:latest

The session below shows the live action.

root@lumi:~# docker run --privileged -p 5010:5010 -d -it --name=home-web-ir -v /var/run/lirc:/var/run/lirc josemottalopes/home-web-ir:latest
Unable to find image 'josemottalopes/home-web-ir:latest' locally
latest: Pulling from josemottalopes/home-web-ir
0d9fbbfaa2cd: Already exists
b015fdc7d33a: Already exists
60aaa226f085: Already exists
01963091a185: Already exists
a289a8a5c81a: Already exists
9432c55829c7: Already exists
87334e3159b5: Already exists
08a216585c0f: Pull complete
ac1e370475ca: Pull complete
ed21dfb3a130: Pull complete
885b38cb4c35: Pull complete
f8526fd2a07f: Pull complete
Digest: sha256:c374826cfd091ed89fb9da3992bad4d06488fb0152a44d5110401f5ff41de793
Status: Downloaded newer image for josemottalopes/home-web-ir:latest

Please check further instructions about updating RPI with latest images in order to optimize your RPI memory.

Checking results

There are a couple ways to check home-web-ir with Internet browser. We can use the "Try it out!" button from Swagger IO and see detailed response, like message body, response code and headers, etc. Another simple way is to address the service directly at the browser, using the curl command or the "Request URL" field provided by Swagger IO.

Following are examples taken from a x64 machine with Windows 10, showing the installed remotes at RPI host.

We just need to append the remote name to previous address to GET its respective IR codes, as shown below.

Testing the IR output requires the swagger IO interface, to generate the POST command with "Try it out!" button. You can notice that Samsung monitor answered to "KEY_VOLUMEUP" command as expected.


First, at this mission, we improved the API to a new version, adding infrared support to the Thing device. SwaggerHub automatically generated the code for us, adding a new Controller that was merged to home-web project.

The generated code was tweaked into a simple solution that shows a RPI wired to IR leds growing into an embryo of a universal IR remote control. You can then use http to blast commands to a big legacy of IR controlled home gadgets, like air conditioner, heater, RGB light, tv, home teather, etc. Over #2,500 remotes are available at Lirc database, there's a big chance yours are already there!

Depending on your application objectives, you should now develop a custom home-ui project that handles the user interface, using RemoteApi as starting point! Current ASP.NET MVC home-ui is a suggestion, off course there are many other tools able to benefit from home-web API. But remember that since both use same .NET platform, current home-web and home-ui share some image layers, optimizing memory.

I hope you enjoyed this series, I learned at lot for sure.

Have fun with IoT.Starter.Pi.Thing and IoT.Starter.Pi.Lumi to speed up your IoT initiatives!


starter kit IoT.Starter.Pi.Thing IoT.Starter.Pi.Lumi
Useful for:               all projects                        infrared (IR) projects
Description: embryo for IoT IR embryo for IoT, powered by Lirc
SSL proxy: nginx-proxy nginx-proxy
User Interface: home-ui home-ui
Web Service: home-web home-web-ir

Please comment, fork the repos and use docker images to start nice IoT projects!

Have fun!



This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Jose Motta
Systems Engineer
Brazil Brazil
Electronic Engineer UFRJ 1977, M.Sc. Computer Systems COPPE 1982, CEPEL Researcher until 1985, Mira Informatica CEO until 1995, TRENDnet Brazil CEO until 2015, IoT Systems & Architecture.

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