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CoClimber
02-25-2021, 04:58 PM
While building my Kitfox, I've been toying with various electronic instrument ideas. I hope to fire up the 912 this weekend so will be able to test the EMS, but I have a flight scheduled in a Cessna 150 tomorrow so will bring my latest version of an EFIS. It gets its flight info from a Pixhawk drone controller and displays it on a 3.5" 320x480 display. Currently it has GPS ground speed, pressure driven altitude and vertical speed, AI, slip, and rate of turn. After tomorrows test, I want to add air speed because ground speed can be found on my tablet and air speed is far more important for aviating.

The colors in the photo aren't accurate. Also, I can't believe the photo was rotated when I attached it.

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109JB
02-25-2021, 06:15 PM
Hi CoClimber,

Is the display sunlight readable? If so would you mind telling me which display you are using?

Thanks,

CoClimber
02-26-2021, 07:58 AM
John, I guess I'll find out today. I did have the unit out a week ago in the car driving to the airport. I cancelled my flight but played with the display on the drive home (had my wife drive). I never had an issue with seeing it but will try to evaluate it under more difficult conditions. It is just this display: https://www.amazon.com/gp/product/B08CN6M9VC/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

I drive it with a Teensy 4 which has enough memory that I can buffer the display to eliminate flicker.

CoClimber
02-26-2021, 02:40 PM
Okay, Just got back from a nice sunny flight. The EFIS spent most of the time up on the glare shield. I would rate the brightness as adequate. Not great but I could see it okay. I think that once it is in my panel it will be better. Furthermore, it has an LED backlight and that could be made brighter. The touch screen reflects badly so the angle is important. It would be interesting to see if a non glare film could be placed over it.

Regarding the performance, the slip indicator was crap. Useless. I'll look into the math. Airspeed, vertical speed, and altitude were very close to the panel instruments as expected. The big expectation with an inexpensive MEMS based gyro is that it will drift which makes pitch and roll measurements drift. Mine was solid. The kalman filter does use the GPS so I'm not surprised. At no point in the flight did I see that the attitude was wrong.

Being a tinkerer, my plan was to design this for a 3" hole so that if it doesn't work, I can buy a Garmin G5, etc. However, from what I saw today, it will work fine. Just need a bubble level for the slip. :)

CoClimber
02-27-2021, 11:14 AM
Hi CoClimber,

Is the display sunlight readable? If so would you mind telling me which display you are using?

Thanks,

I'm wondering if you have had any luck sourcing a better display. I want to stick with the 3.5" because it works well with a 3" panel hole. I got my engine fired up today and, while the EMS was useable, it could be better.
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109JB
02-27-2021, 11:56 AM
Not a cheap one. I am going to build my own engine monitor and decided to go with a monochrome display. Would like to make a color one with graphical display, but for now at least it is going to be monochrome text much like a GRT EIS

109JB
02-27-2021, 12:05 PM
A question for you. I saw your post on the Facebook forum with the video. For the tach pickup what kind of circuit are you using to feed the tach input to the microcontroller?

Thanks

CoClimber
02-27-2021, 12:08 PM
I use some great OLED displays at work that perform well in sunlight. However, I really wanted the color and higher resolution. I like the idea that I can tell at a glance if everything is okay. Red is bad! However, if I can't see it, it does me no good.

CoClimber
02-27-2021, 12:13 PM
A question for you. I saw your post on the Facebook forum with the video. For the tach pickup what kind of circuit are you using to feed the tach input to the microcontroller?

Thanks

It is a crude circuit with a comparator with a built in voltage reference. MCP65R41. I have a resistor in series with the input and two diodes to limit the voltage to 0-3.3V. I want to get a scope on it but don't want to drag out the Tektronics MDO3024 into this weather. I don't think my company would appreciate that. I suspect I will add some analog filtering later.

109JB
02-27-2021, 02:12 PM
What I'm planning for exceedances is a couple of LEDs in combination with the monochrome display. One amber for warnings, and one red for to high/low. The LEDs will be toward the top of the panel right in front of the pilot since the display is toward the bottom of the panel and might not be as noticeable there.

CoClimber
02-28-2021, 01:15 PM
What I'm planning for exceedances is a couple of LEDs in combination with the monochrome display. One amber for warnings, and one red for to high/low. The LEDs will be toward the top of the panel right in front of the pilot since the display is toward the bottom of the panel and might not be as noticeable there.


I like your solution. Let me know if I can help.