Using Buildroot for IoT Projects

Buildroot RPi Yocto Logos

Early on in my effort to build a digital dash for my car I quickly realised I needed to run a stripped down version of Linux if I was to have any chance of getting the dash to boot up quickly on the Raspberry Pi. A dash that kept you waiting for tens of seconds or at worst minutes to turn on wouldn’t exactly be the most practical of solutions (especially if you want to avoid speeding fines hehe).

So I was faced with the situation of taking one of the existing distributions available for the RPi and modding it for my own use, or having a crack at making something myself that would do the job. Initially I did start tinkering around with seeing how fast I could get stripped down versions of Raspbian and Arch booting up, which although was interesting did feel as though I was spending a lot of time and effort digging down in the dirt and undoing a lot of work someone else had already spent a lot of time doing. Therefor instead of trying to tear something down to suit my needs, I decided to focus my attention to incrementally building something useful from the ground up. I figured doing it this was would be a great source of learning as I would no doubt begin to run into obstacles other people have already created solutions for, meaning I would appreciate the open source communities hard work even more so.

After a bit of searching I found a couple of promising looking projects to base my dash on (I really didn’t feel like totally reinventing the wheel). Both Buildroot and the Yocto Project share the common goal of creating a complete, easy to customise, embedded Linux system. Both compile Linux from source using cross-compilation (which should cover most performance requirements), are well documented, actively maintained and already used within the embedded systems industry. In fact I had already been exposed to the Yocto project before without even realising when I attended an Intel Edison workshop at the London FabLab, as the Linux image supplied by Intel for use on the Edison is a Yocto build.

Whilst I already had some experience with Yocto I decided to kickstart my digital dash using using Buildroot. Namely in the effort of simplicity as to get started with Buildroot is just so easy. The documentation available is awesome and provides a steady learning curve. I also found a pretty good short book on using Buildroot with the RPi which was neat primer. After a bit of tinkering I had the environment setup in a Ubuntu VM as well as a working filesystem that booted in seconds on my RPi2. I quickly appreciated the number of tools available out of the box in major Linux distributions as theres really not much to do in a basic buildroot build other than logging in and a few system utils to work with.

It was not before long I had my buildroot environment stored under Git and had automated a few of the basic build commands, such as copying over custom apps after a successful build and flashing the filesystem to SD card. All in all it didn’t take a ton of effort to get a simple enough system working that booted up fast, was capable of connecting to the Internet and launched my prototype app on boot. My prototype app is built using QT with PyQT bindings, both of which buildroot supports although not the latest versions.
I would happily recommend Buildroot to anyone who wants to learn more about Linux targeted for embedded devices and IoT projects, it really is a pleasure to work with and the community behind it is very resourceful and helpful.

Looking towards the future for my digital dash there may come a time where I may have to look to migrating towards other projects like Yocto. Buildroot is great and pretty much does everything I need at this point in time, however it does have what I consider to be quite a big no-go – especially in the IoT community. There is no package management system and no binary packages, meaning updates to the system are not possible via packages. If a future release of the Linux kernel fixes a security vulnerability, a full system update would be required which would involve physically removing the SD card and updating the software manually. Best practices for building IoT devices include having an inbuilt mechanism from the word go, allowing for critical updates to be issued that threaten to compromise the device without having to rely on the end user to manually update their device.

All of this is subject to change I guess, Buildroot could one day change how they do things. For now I’m sticking with them as I’m the only one working on the dash project, but being the responsible security guy I am if I open up the project for others to tinker with I would want to switch to another project that supported some form of inbuilt updating.

Anyway it’s about time I get back to finishing rebuilding the engine for the Mk1 so I can actually test the dash in-car for once instead of on my desk!

MegaSquirt 3 Digital Dash

I am pleased to announce and introduce a little side project that I have been working on the past few months (years). The projects initial main focus is to create a HD digital dashboard for the MegaSquirt ECU, to be built using as much COTS (commercial off the shelf) hardware as possible. This means that hopefully with some conscious design planning it should be possible to produce copies fairly easily just by following some documentation and ordering a few bits of the Internet here and there (This is the plan at least, who knows how things will pan out). Theres no reason other ECUs can’t also be supported in the future, however thats the only aftermarket ECU I have at hand and since thats what I run in my cars.

Project Brief

Create a digital dashboard that respects the character and history of the original cluster gauge, whilst also providing access to additional metrics that are critical for any high performance or turbocharged engine.

And so after a bit of hard work this is what I have come up with for now..

Mk1 Escort Digital Dash
The original dash is on the left (front cover removed)

The dash features an 8 inch 1080P LCD display powered by a Raspberry Pi 2 (soon to be RPi 3) running a stripped down build of Linux to allow for fast booting. The dash communicates with the cars MS3 ECU via CAN bus and will include some additional power features that allow it to turn on/off safety via a switched ignition input.

The main motivation for having a digital dash is to take advantage of displaying all the extra sensor data the MS3 ECU utilises and accumulates. There are sensor outputs and ECU calculations that I would be interested in knowing whilst driving, but at the same time I don’t with to clutter the dash with additional gauges and dials as that would spoil the general aesthetics of the interior. Creating a digital dash in the same style as the original dials is a good compromise on having access to the data and not ignoring the originality of the car.

The development and install of the first dashboard will be a prototype version retrofitted into my Mk1 Escort. This type of instrumentation is something that I have wanted for many years, however it wasn’t until recently that I felt I had gained the right knowledge sets and courage to attempt such a project and not forgetting the funds to back. Believe me when I say this has been a long time in the works.

I will post more details on the project in the upcoming weeks but for now just wanted to give a glimpse into some of the more complicated long term projects I’m working on.