Build Your Own Avionics Suite, If You Dare

If you’re really interested in aircraft and flying, there are many ways to explore that interest. There are models of a wide range of sizes and complexities that are powered and remote-controlled, and even some small lightweight aircraft that can get you airborne yourself for a minimum of expense. If you’re lucky enough to have your own proper airplane, though, and you’re really into open source projects, you can also replace your airplane’s avionics kit with your own open source one.

Avionics are the electronics that control and monitor the aircraft, and they’re a significant part of the aircraft’s ability to fly properly. This avionics package from [j-omega] (who can also be found on will fit onto a small aircraft engine and monitor things like oil temperature, RPM, coolant temperature, and a wide array of other features of the engine. It’s based on an ATmega microcontroller, and has open-source schematics for the entire project and instructions for building it yourself. Right now it doesn’t seem like the firmware is available on the GitHub page yet, but will hopefully be posted soon for anyone who’s interested in an open-source avionics package like this.

The project page does mention that this is experimental as well, so it might not be advised to use in your own personal aircraft without some proper testing first. That being said, if you’ve heard that warning and have decided just to stay on the ground, it’s possible to have a great experience without getting in a real airplane at all.

25 thoughts on “Build Your Own Avionics Suite, If You Dare

  1. “The project page does mention that this is experimental as well, so it might not be advised to use in your own personal aircraft without some proper testing first.”

    you probably misunderstood that…in order to legally fly with DIY…anything… as a part of your plane, it (the plane) has to be registered as “experimental”, otherwise anything you bolt onto it needs certification from the authorities. This applies to mostly US, as not that many countries allow amateur experimental aircraft.

    One way to partially skirt around would be to have the certified instruments installed as well, but the DIYed ones must not interfere with them and you can’t do anything that would void the aircraft’s certification.

    1. thats not completely correct. under certain CAA is possible to fit non certified instruments as long as they are not primary and not interfere with the primary instruments. not sure any engine instrument is compulsory for VFR.
      on ULM, PtF and Experimental any instrument can be fitted, and in most of the world ULM/Microlight now constitute the bulk of the light aviation.

      1. § 91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

        (b)Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:

        (4) Tachometer for each engine.

        (5) Oil pressure gauge for each engine using pressure system.

        (6) Temperature gauge for each liquid-cooled engine.

        (7) Oil temperature gauge for each air-cooled engine.

        (8) Manifold pressure gauge for each altitude engine.

        1. I’d assume [gianmarco] is not talking about US regulations based on the terminology he’s using.

          In the US, experimental category aircraft are not required to have certified instruments. Ultralights (<254lbs/115kg, single pilot, plus many other limitations) aren't even considered "aircraft" so have no requirements for instruments at all.

          US Standard category aircraft must have certified instruments and, as [Duo] quotes, these are required to include certain engine monitoring equipment. You could not legally install the DIY engine monitoring system in such an aircraft as it is not certified.

          The US also has the somewhat unique "special light sport" aviation category, which covers certain aircraft with a maximum 600kg takeoff weight and no more than two occupants. These might be considered "ultralight" in other countries. A Light Sport Aircraft is not subject to the Minimum Equipment List of 91.205 above and would not require certified instruments, *however* you would require an authorization from the aircraft's manufacturer in order to modify its existing equipment. It's unlikely that any responsible manufacturer would grant you this.

          tl;dr – in the US, anyone with an ultralight or experimental aircraft could use this, everyone else is probably SOL.

    2. This.
      I’m not saying don’t do it, but you should be absolutely certain your doing it right. Something as seemingly innocent as mounting a stand-alone GPS, if done incorrectly, can change the aircraft’s certification requirements, and could even require the pilot have a specific rating on his/her license.

  2. Ultralight aircraft generally don’t need type certification, but rules vary wildly (ultralights are the only class without international regulations, afaik).

    This can obviously only be used in uncertified ultralight craft under daytime-vfr, where your safety isn’t compromised by failure of these instruments.

  3. Hey bud, I want to give you a big thumbs up. $250 for the experimental community is a far cry from a certificated device.
    Went through the readme and saw no indication of what you’re testing it with. I’d be interested.

  4. that looks IDENTICAL to the GRT Avionics EIS. i had one on my previous aircraft. i just checked and the company is still in business so i am very surprised to see this advertised as “open source”
    firmware is not available anyway and without that, its very useless.
    and btw, i have developed and i am testing on my airplane an arduino based engine monitor, much simpler than this, requires no setup, designed for the rotax 912 series engine.

      1. no CANaerospace. mine is a minimalistic approach, it is very simple, very cheap, and uses the standard sensors factory fitted to the engine, plus a couple extra sensors for MAP, fuel pressure, ambient air temp and humidity, being fuel pressure a vital parameter to monitor, and a parameter that is often not monitored at all, with the result that you discover the fuel pressure dropped to zero when things get suddenly very quiet.
        this is how it is fitted to my a/c
        the approach is that you do not need to look at the instrument all the time, something pilots anyway never do; if any parameter goes outside the limits, an acustic and visual alarm will be raised.
        this is an instrument i built for all those pilots who cant or dont want to spend hours fiddling with setting up parameters, and who are willing to switch from a pletora of next to useless gauges to something more advanced, cheap, light.
        my a/c is a MCR01 Sporster. 140+ knots cruise speed on a 100hp powerplant.

    1. Hey gianmarco,

      that sounds quite interesting and you’re right, the project is missing some essential part, but I am pretty sure (and hoping) that jomega is just cleaning up his code and will submit it soon ;o)

      When you say “rotax 912”, does this mean, your Arduino speaks CANaerospace? And which aircraft is it pulling through the skies?
      Would be very much interested to learn more about your project…

  5. Nope for me. I take my flights very serious, and if I am looking at this gauge and it shows incorrect information and thought causes me to do something I would during a normal flight and heaven forbid I crash and/or cause harm to someone, it would be 100% my fault.

    I like having certified equipment by a company/entity that give me assurance. And for the flamers, yes a certified widget can still fail, still cause a crash, but my insurance would take care of those harmed as well as me due to the fact I followed proper procedure.

    1. my experience is that cerfidied equipment is often more faulty than the uncertified version, reason being that in an uncertifed piece of equipment if a defect is found, it is corrected. on a certified piece of equipment this often will not happen as a modification means recertification, with huge costs.
      moreover certified eqyuipment is almost always 10 years behind the curve, and it is always a LOT more expensive, often without apparent reason.
      if you want an example, look at the garmin g5. the uncertified version costs 50% less and has more features.
      your claim that “i take my flights very seriously” implies that those who do not use certified equipment do not take their flights seriously, which is utter nonsense.
      i am not on a suicide mission and i fly with my son too, and the reason i do not use certified equipment is because i looked inside these things, and they are no better. in fact, they are on many levels a lot worse. look at a garmin 430, does that look like a modern GPS? nope, it doesnt, and it costs a fortune.
      the GRP EIS, which i used for many years, is a solid piece of equipment, super reliable, and far superior to a lot of other stuff on the market.

      1. Hey Gianmarco,

        thanks for your replies and the details… three thumbs up for the simplistic approach, design and above all, the acustic warning… I also found those who spent tons of money for their oh so serious equipment spending way too much time looking at their fancy MFDs and playing with their pads instead of watching out for other air traffic or just enjoying the outside view…
        If you decide to put your project into the open, please let me know, I’d be very interested to follow. I could also share my experience with the CANaerospace protocol, if you’d like…

        j-omega now seems to have put his code online, big thanks for that, too. Will definitely have a closer look at it, I like the simplistic approach already!

        1. hello Michael
          i had a look yesterday at the firmware and it really looks like j-omega is tring to copy the GRP EIS also in the software, something i have mixed feelings about. apart eventual legal issues, J-omega unit, like the GRP EIS, is designed to work with a wide range of engines, from the rotax 2 cyl 2 stroke to the big flat six conti and lyco.
          this will require a LOT of testing, missing which all those who will decide to build and use this monitor will have every sort of issues and problems, and will have to deal with a complex firmware.
          thats why i chose a simplistic approach, and even adapting my simple device to a single type of engine is requiring a lot of testing and several hw and sw modifications. and should i mention i dont have an engine to test in my workshop, and that i need to do all the testing at the airfield, carrying with me in the hangar tons of equipment?
          i am not planning to release my sw to the public, reasons being that:
          1) i dont want others to see how crappy my code is :D
          2) i spent a lot of time ed effort doing this, and i stopped doing probono work long time ago.
          3) i wont have time to deal with the support requests and questions of all the users.
          i have given my engine monitor to a few friends and ALL of them managed to fry it during installation…dont ask me how… supporting and fixing these and shipping back and forth is already very time consuming and thats only a few units.
          i have also delevoped a digital ASI/ALT/VS instrument which works extremely well, gray code and serial altitude encoders for xpnds, trim controllers, led based strobe lights, a 4xCHT designed for the VW derivatives, and a few more small projects.

  6. “Avionics are the electronics that control and monitor the aircraft”

    As I understand it, “avionics” is a portmanteau of aviation electronics, and includes radios/intercom, radar, etc.
    As opposed I suppose, to an electronic entertainment system.

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