Halloween Scare 2016

by Mike Linnen 28. October 2016 21:06

I kicked off another Halloween project this year and I posted it on GitHub for everyone to see and use if they like.  This project has focused around building smart devices that are all connected via an MQTT bus.  I wanted to have something that I could build on every year.  The devices are either actuators or sensors that are smart enough to serve a purpose and can be orchestrated into a bigger animation scene using a workflow engine such as Node-red.  Anyways check out the project on Hackster.io and GitHub.

Windows 10 IoT Core powered garage door

by Mike Linnen 6. October 2015 23:03

I wrote an article on using the Raspberry Pi 2 Model B for a contest on Hackster.io.  This project focuses on using the Alljoyn messaging framework. Head on over to Hackster.io for my Garage door powered by Win 10 and the Raspberry Pi project.  Here is a video demo of the project.

Continuous Delivery on a Spark.io

by Mike Linnen 15. February 2015 23:11

I have always wanted to remotely update my IoT devices when they are in need of a software change.  It is really a pain when I have to disassemble a dedicated device just because I need to update the software that is embedded in it.  It has been so much of a pain for me I have gone as far as trying to make the device as dumb as possible and leave the smarts in a service located on a computer with an OS that supports remote access.  Doing so seems to make the device just a remote I/O extension and not an actual Smart Device. 

Continuous delivery takes the remote update one step further.  If I have a source control repository that I commit some new code to, then my automated process should be smart enough to pick up that change, compile, test and deploy the new bits to it’s final destination.  Wow wouldn’t that be cool!!!

In order to do this the device would need to be smart enough to support a remote update process.  That means a device would have to be able to check for updates and automatically apply them.  You could write your own remote update process and I have done this many times for desktop applications, but doing this on an embedded device is little more tricky.  Sometimes it would require you to actually change the device firmware especially if the device doesn’t support dynamically loaded software.  Basically the process to do so would require you to do the following:

  • Detect if an update exists on some remotely accessible resource
  • Download the update and unpack it
  • Unload the current version of the software
  • Load the new version of the software
  • Start executing the new version
  • Do this reliably without bricking the device

Fortunately the Spark.Io platform does all this for you so you don’t have to.  The platform even supports an open source backend that will take source code, compile and deploy it.  Now that makes it very possible to do continuous delivery for IoT devices.  The rest of this blog post will explain how easy it is to set this up.

There are several things you will need to have in order to accomplish this:

  1. A Spark.io account and a device that is connected/registered with the account.
  2. A source control repository that is supported by your CI tool of choice (I am using GitHub)
  3. A build script that can either call restful APIs or can shell out to curl.exe (I am using psake with curl.exe).
  4. A CI tool that watches the source control for commits and kicks off the build process (I am using Team City on a Windows Azure VM).

You can see my source repository over at SparkContinuousDeliveryExample. Feel free to fork it and use it if you like.  I used psake as my build scripting language of choice as it is supported by Team City and I find it very easy to understand. 

Build script

My build script is called default.ps1.

properties { 
  $deviceId = $env:SparkDeviceId 
  $token = $env:SparkToken 
  $base_dir = resolve-path . 
  $curl = "$base_dir\lib\curl\curl.exe" 

task default -depends Deploy

task Clean { 

task Deploy { 
  $url = "https://api.spark.io/v1/devices/" + $deviceId + "?access_token=" + $token 
  exec { 
     .$curl -X PUT -F file=@src\helloworld.ino "$url" -k 

} -depends Clean

task ? -Description "Helper to display task info" { 

The first thing you will notice is that the script takes 4 parameters that are defaulted but also can be overridden by Team City.  The $deviceId represents the spark.io device Id and can be found in the spark.io build website after you have logged in and picked one of your devices.  The $token is your spark.io access token and can be found in the spark.io build website after you have logged in and selected the settings menu option.  You really only have 1 access token for an account but you could have multiple device id’s for an account.  The other 2 parameters are really only for executing the curl.exe program that interfaces with the spark.io platform.  Since the repository has the curl.exe you wont have to worry about installing it on your build server, but if you don’t like putting EXE’s in your repository you could override these parameters to launch the curl.exe that is installed on your build agent. The Deploy task is the only task in this build script that does anything.  Basically it launches curl.exe passing in the device id, token and the file name to upload to the spark.io platform for compilation and deployment.  In this case the program source file is helloworld.ino.

Testing the build script locally

You can test the psake build script on your local machine by first setting the environment variables for the $env:SparkDeviceId and $env:SparkToken.


Of course I didn’t include my real Device ID and Token in the example above so make sure you set them using your own Spark.io settings.

Make sure you are in the directory where you cloned the repository and use the Invoke-psake keyword to kick off the build.


Your code will be uploaded to spark.io, compiled and then deployed to your device.  As you can see here the process completed successfully.

Setting up Team City:

You will have to follow the instructions on the Team City web site on how to install Team City.  It is very easy to do but I wont detail it here.  I am also going to ignore the step of setting up Team City to connect to your Github repository. Assuming you have a project created in Team City and you have assigned the VCS root to the project you need a build step added to your project.  You want to make sure you select Powershell as the runner type.  See the other options I selected in the following screen snapshot:


Make sure you select Source Code as the script type and then type in the powershell script but make sure you replace the YourDeviceId and YourToken.


Here is the script so you can copy and paste it easier.

import-module .\lib\psake\psake.psm1
invoke-psake .\default.ps1 -properties @{"deviceId"="YourID";"token"="YourToken"}
if ($psake.build_success -eq $false) {exit 1} else { exit 0}

Here are the rest of the options to finish off the build step:


And that is all there is to it.  You will want to add a Trigger to your build project so that it fires off a build when source is committed to the repository.  Also make sure you have the VCS Root pointed to the “master” branch.  Now whenever you commit changes to the master branch the build will pick it up and send it off to Spark.io for compile and deploy.


  • Works on single file source solutions at this time.
  • If a compile error exists the build does not fail (but the device does not update).
  • If you edit the readme or any other non-source files and commit it then the device gets updated even though no source changes were made.


  • Get this working on a free hosted build platform
  • Use a Raspberry PI as a build server
  • Remove the dependency on curl.exe and use powershell to make the REST api calls
  • Add in multi-file support
  • If the Spark.io platform is down fail the build
  • Make sure a compile error fails the build


That is all I wanted to cover on this blog post.  Of course there a million other ways you could set this up and I would also like to hear how others might do this.  I have always dreaded pulling devices apart just to upgrade them and therefore I tended to not update them as frequently as I would like.  I just need to get the hardware nailed down on some projects so that I can get them installed and hooked up to a build.

Garage door and the Spark Core on github

by Mike Linnen 25. December 2014 21:11

I just posted my initial code for my Garage door project using the Spark Core on github.  This is a work in progress and will evolve over time.

Garage door and the Spark Core

by Mike Linnen 20. December 2014 01:21

I recently moved to a new home and I now have 2 garage doors to control instead of one.  So I decided to revamp my garage door home automation project by using the Spark Core.  This is a fascinating device as it is designed to connect to the Spark.IO cloud service without doing a lot of coding to maintain the connectivity to the cloud.  The default firmware in the device allows you to remotely connect to it and invoke functions, expose variables to the cloud service as well as perform pub/sub between devices.  Make sure you check out their website to gain a better understanding of all the capabilities of this small packaged IoT controller.

My goals in this project was to achieve the following:

  • know when either garage door is opened or closed.
  • remotely close or open the garage door.
  • have the door automatically close when I go to bed.
  • keep track of how long it takes to open/close the garage door.
    • if the door starts to take longer to open and close this might be a sign that it needs maintenance.
  • automatically open the garage door when I arrive home.
  • automatically close the garage door when I leave my home.
  • notify me when the door needs maintenance because it has been opened/closed so many times.
  • monitor the temperature and humidity in the garage.
  • monitor the garage for motion when the security system is on.
  • notify me that I left the door open after a specific time of night.

That is certainly a large number of goals and I don’t intend to complete all of them initially but you kind of get the idea of what the possibilities are.

Initially I intended to do all of this for 2 garage doors with one Spark Core, but after thinking about it a bit it made more sense to use at least two Spark Cores

One thing I decided to do right off the bat is to make sure I have enough sensors that could determine when the door was opened and when it was closed.  I have seen other remote garage door projects that simply have one sensor that detects if the door is closed or not.  I wanted more inputs so that I could time how long it took for a door to complete it’s open or close command.  I want to keep track of this in order to determine if the door will need maintenance when it starts to take longer to open or close.  I can also gather a little more analytics around the timing of the door command and the temperature in the garage.  I don’t know if I will use this more detailed information for anything or not but I thought it would be fun to play around with.

So I will have 2 magnetic reed switches that I plan on placing on the door track to determine if the door is closed or opened.  The status of the door will be 5 different states: opened, closed, opening, closing and unknown.  The unknown state will only be for when neither of the sensors are triggered and the device doesn’t know if the door was previously opened or closed.  I have most of the code written to handle the basic door operations and I will be sharing that code in a future post.

So stay tuned on future posts on this topic as I move forward with it.  Please feel free to give me feedback or ask questions on items I haven’t clarified very well.  I am very interested in anyone’s thoughts on the Spark Core as well as home automation in general.

BuilderFaire track at Raleigh Code Camp 2014

by Mike Linnen 8. November 2014 10:04

I gave a talk at the Raleigh Code Camp called "What can I do with a Raspberry PI". The slide deck is attached to this post for those of you that attended.

Raspberry PIv2.pptx (6.67 mb)

Raleigh Code Camp 2013 Netduino Azure Session

by Mike Linnen 30. October 2013 21:31

I am presenting two sessions in the Raleigh Code Camp 2013 Builder Faire track on November 9th.  The first session is called Building a cloud enabled home security system Part 1 of 2 (the presentation).  The second session is Building a cloud enabled home security system Part 2 of 2 (the lab).  You really need to come to both sessions as the first session explains what you will be building in the second session.  Yes I said that right, if you attend the second session you will be building a Netduino based security system that connects to Windows Azure.  Check out the project website for more details at Cloud Home Security.

I hope to see you there!!

Carolina Code Camp 2013 Netduino Azure Session

by Mike Linnen 3. May 2013 21:39

I am presenting 2 sessions in the Carolina Code Camp 2013 Builder Faire track.  The first session is called Building a Home Security System – The Introduction.  The second session is Building a Home Security System – The Lab.  You really need to come to both sessions as the first session explains what you will be building in the second session.  Yes I said that right, if you attend the second session you will be building a Netduino based security system that connects to Windows Azure.  Check out the project website for more details at Cloud Home Security.    

Demo connecting 11 Netduinos to Windows Azure Service

by Mike Linnen 14. February 2013 23:28

I put together a talk that includes a lab on building a security/home automation system using 11 netduinos communicating over MQTT with a broker located in Windows Azure.  The attendees of this talk will walk through the lab and build out various components of a security system.

Here is a video demonstrating the various components of the system.  

The source for the project can be found on github:

The Security System website is hosted on a Web Role and it contains all the documentation for the lab.

Announcing: Hands on Hacknight connecting Netduino's to an Azure cloud service

by Mike Linnen 27. October 2012 00:00

In December I will be presenting this talk for the Charlotte Alt.Net users group. This talk is less about presenting and more about actually coding up a device that connects to the cloud.

This is not a sit back and watch the speaker meeting. As a participant in this project you will be building the devices that complete a Simulated Home Security system. There will be some basic code that is written for you but for the most part it will be your job to complete the code and make the device functional. The cloud service that connects all the devices via a message bus will already be completed and deployed to Windows Azure for you to use. Your device will publish and subscribe to messages on the bus.

Come out to the event and learn how to connect a Netduino Plus to Windows Azure.

Head on over to the meeting invite and sign up now.

About the author

Mike Linnen

Software Engineer specializing in Microsoft Technologies

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