Anyone build their own engine monitor?

[kmacht]

I'm doing a panel upgrade on my Sonex which means it is time to change out the old black and white MGL Stratomaster Ultra. I have the EFIS and backup instrument side of things figured out for the panel but need an engine monitor. I looked to see what is out there and the cheapest I can find is the MGL E1 for about $500. The downside is that it only displays 4 thermocouples instead of 8 and doesn't have any logging capability. I am toying with the idea of building an engine monitor myself and thought that might be others on here have done the same or are in the process of a similar project. My current though unless someone has something better is to use an arduino to read and interpret the basic sensor data (sort of like an MRL RDAC) and then use a 4D Systems display and VisGenie to create a screen on the panel that displays the data as gages. Investment in the arduino, display, and software looks to be only about $100 so I'm not out much if this doesn't work.

Keith
#554

[Bryan Cotton]

I was absolutely going to do this for my Hummelbird, but had also planned for all the air data as well. I have a Microchip PIC development environment from the prior millennium. I had gone as far as designing the board and had bought components and then someone gave me a free Braüniger Alpha MFD. That is going in my Waiex.

So - why not? Should be fun.

[T41pilot]

I don't see why you couldn't use an Arduino to do that. Reading the sensor data is probably the easier part. Displaying it would take more work. I made my own capacitive fuel probe with a Bargraph to display fuel level that works just fine.(In my Ultralight) I haven't mounted my current probe in the Sonex yet because the tank isn't installed, but test runs in a tube of fuel look fine. Probably have 25 bucks in parts. If you end up playing with the idea, just remember to use a smoothing(averaging) routine to settle down the sensor readings. They'll be bouncing around too much without. I'm not a programmer but just cut and paste bits of already existing programs to do what I want. I'll be displaying my Flap position and elevator trim position with Arduino's help as well. I use Attiny 85 chips for the small stuff and atmega328 chips for the display stuff. Dirt cheap for the parts.

[sonex892.]

Check out Experimental Avionics. http://experimentalavionics.com/ For about $300 you can build a complete engine and flight instrument system. The only downside is that it is monochrome. He sells PC boards, the LTC 2983 chip and a few other things. Most of the components can be inexpensively sourced from China. I found Oleg the guy who runs EA is quite helpful.
Iv'e built both the EFIS and EMS. They are Arduino based. The EMS wiring structure is inputs to a chip in the engine bay then a canbus link to the display. The same as MGL display to RDAC. The engine bay chip 20 has inputs that can be configured to read temps from all devices thermocouple / RTD / diodes and transistors.
Whilst I have both the EFIS and EMS functioning, I have not flown with them. The base of the arduino code is available on the website, but you will need to be familiar with the code or learn. There are a wealth of great tutorials on youtube.
Steve
Sonex 892

[Bryan Cotton]

I'll have to look at my old parts. I had a 4 line serial LCD display which would be fine for temperature display.

[kmacht]

For the display I am leaning towards using one from 4D systems. They have a software program called VisiGenie that allows you to drag and drop different gages, displays, and buttons on to their touchscreen display and it will generate all the code needed to have them interact with the arduino. Their newer displays also have 16 GPIO's so it may be possible to make the monitor without an arduino at all depending on how many sensors I end up with.

Thanks for the link to experimentalavionics. That is exactly what I want to make (without the EFIS side) but with a color touchscreen display.

Keith
#554

[lutorm]

I haven't done anything for our Sonex, but as part of my project to convert an old carbureted motorcycle to EFI, I did build an "I/O" module, using an Arduino, that sends measurements to the Megasquirt ECU over CAN-bus. The measurements in this case are mostly the lambda sensors, but it also translates the ECU outputs for the "OG" RPM and temp gauges in the instrument cluster.

Like someone said, I don't think it's a big deal to build something that reads the sensors. However, making a display for it is a rabbit hole of UI design and coding. I think if at all possible you should interface with your existing EFIS for the display. Even if the protocol used to send data to the EFIS isn't documented, I think it's likely to be less work to reverse-engineer it than to write a display controller and UI from scratch. If you send the data to the EFIS you'll also get data logging for free, and IMHO logging engine data is a must-have for monitoring and tuning.

[kmacht]

The 4d Systems products seem to take all the guess work out of how to make a GUI and doesn't require anything but basic coding knowledge. Their software does all the coding for you. I have also found that you can have the arduino convert the sensor data into CAN format and then export that into the torque app on your phone with a wi-fi adaptor. The torque app already has all the displays for a typical engine monitor and data logging capability. It may take more manual coding to get that to work but wouldn't require the purchase of another display screen.

Keiht
#554

[PeterNYNJ]

I did the same thing (built an EMS) for the same reasons a while back.
I built an EMS around an Arduino and some spare parts to monitor 7 thermocouples with a 2x20 character LCD for less than $50 I think.
It worked Okay on the Aerovee but I haven't had time to refine it yet. But it can be done...

[kmacht]

For those thinking about doing something similar I found a pretty simple solution for the EGT and CHT thermocuples. Adafruit makes a MAX31850K thermocouple amplifier that has 1-wire support. The board has a built in voltage regulator as well as cold reference compensation and 1-wire support allows you to daisy chain as many of the boards as you want by just connecting their data and ground wires to the next board. You only need 1 pin on the arduino to read the output from all the boards. The library does all of the compensation and conversions for you and outputs the data as a temperature so very little programming is needed to use them. I had two of them up and running on the bench outputting temperature to the serial monitor in about an hour.

Keith
#554