Transponder Build

Working on a instrument project or just finished a project? Show it to others!

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JohnF
Posts: 45
Joined: Tue Feb 02, 2021 10:51 am

Transponder Build

#1 Post by JohnF »

I decided that I would use Air Manager as an interface to communicate with X-plane and design and build instruments. This has proved successful although the learning curve was high, not my preferred language to write in. I have selected the Arduino Mega as Air Manager has the capability to interface with this device.
I am designing and building a Bendix King KT74. See my website at http://www.johnf.no/Transponder.html, any advice and comments are welcome, and ideas of future instruments that may be off use.

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jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Transponder Build

#2 Post by jph »

Hi John, looking really nice.
Is the display the original KT74 > ? it looks like a custom LCD.
Nice PCB work also :)
Joe
Joe. CISSP, MSc.

JohnF
Posts: 45
Joined: Tue Feb 02, 2021 10:51 am

Re: Transponder Build

#3 Post by JohnF »

Still ironing out bugs, in software. I will put some pictures and info on my web site later when complete. www.johnf.no ;) . system uses mega and custom display, first time using Arduino and Airmanager LUA so big learning curve.

Mike Horsten
Posts: 79
Joined: Tue Dec 01, 2020 8:50 am

Re: Transponder Build

#4 Post by Mike Horsten »

Really nice work, willing to share the hardware and code for this when your ready. Love to build the same.

Mike
Building a home Cessna 172SP Steam. X-plane/MFS2020
(ex Name on Airmanager forum Polarair)

JohnF
Posts: 45
Joined: Tue Feb 02, 2021 10:51 am

Re: Transponder Build

#5 Post by JohnF »

PM me through web site. Transponder@johnf.no

I will help anyway I can.

JohnF
Posts: 45
Joined: Tue Feb 02, 2021 10:51 am

Re: Transponder Build

#6 Post by JohnF »

Also looking at DME display from Nav1 and Nav2, and a ADF built in to pannel.

jasong
Posts: 101
Joined: Sun Oct 20, 2019 8:18 am

Re: Transponder Build

#7 Post by jasong »

Nice, work, please share if you can, did you have to program the LCD with arduino directly or is AM running the display?
Really cool well done!

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jph
Posts: 2846
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Transponder Build

#8 Post by jph »

jasong wrote: Sat Apr 24, 2021 5:36 am Nice, work, please share if you can, did you have to program the LCD with arduino directly or is AM running the display?
Really cool well done!
Hi Jason,
I am unsure as to what the poster means by a 'custom LCd display'
There is really a binary choice. An LCD with an x by y display, or, a truly custom unit where ALL the display items are hard coded and non changeable.
The second option is no issue if money is no object....., but is very expensive - and I mean - VERY..
It looks to me like the second option so - make your own mind up ;) :D
Joe. CISSP, MSc.

JackZ
Posts: 2262
Joined: Mon Feb 22, 2016 1:02 pm

Re: Transponder Build

#9 Post by JackZ »

Well, nowadays with the currently available pixel addressable LCD screens on the market, and the different Arduino libraries available, one can emulate very expensive custom LCD.
I tried recently some very small 128X32 OLEDS Screens interfaced with AM through message port and the appropriate ug82 Arduino library, along with some custom fonts and the result is satisfying
83ACC4C3-CC41-4B1C-8E4C-1E1CA5B2084E.jpeg
F4095AE6-562E-48A8-971C-F2E8D2A33A64.jpeg
Jacques
My YouTube Chanel on the A320 (Real SOPs by an Airline Pilot IRL):
https://www.youtube.com/playlist?list=P ... 0Q6SBASRqJ

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jph
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Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Transponder Build

#10 Post by jph »

Yes, certainly the OLED units are excellent for certain uses.
I like what you have done there with the back to back 0.91 units. :)
If you need more compact units - which I prefer, then there are the I2C 4 pin units available for next to nothing.
Here's one example from my 'bit box' ;)
The PCB isn't much bigger than the display - the actual oled display is certainly identical in size to your unit. However, the PCB is far far smaller. It gives a lot more flexibility in height gap if needed.
Also, the 4 pins for the I2C part of the PCB can be physically cut off so it is level with the display if needed. There are only 4 simple tracks running to the connector so you can chop off the end of the board and simply wire to the tracks that are left (if you want to ;) ), and the units can then be back to back, and take no real spacing in height ! .. They are the same 0.91 OLED blue 128x32 - but I2C not SPI - Choosing which is 'swings and roundabouts' really.
The ones I have - are - https://www.aliexpress.com/item/4001365 ... 4c4dsI7pXQ

Here's one on my bench -
oled display 12c.jpg
Really neat and extremely cheap.
As you will have found out, the SPI version needs more pins but has a chip select pin in most cases so the actual address of the unit is irrelevant. When used in I2C mode, the 1306 only has 2 possible I2C slave addresses. Either 0x3C or 0X3D - If it is even adjustable on the PCB. But that is also a physical 1306 limitation.
I really like the I2C version Jacques - due to the size...
To run multiple displays is really easy even though the 1306 address range is limited to 2 choices (IN HARDWARE !!!) . All you need is a 4 way or 8 way I2C Multiplexor unit. (about 50c!) you ONLY need the 2 I2C pins and you can address the MUX to tell which output from 0 to 7 is needed (8 units) by a simply command. You can also add multiple muxs for as many displays as you want all with the same I2C hardware pins on the single arduino. Great fun. :D . Each TCA9548A multiplexer board is multi address capable via 3 pins so you can cascade them if you so desire.
An example of a really nice MUX (and virtually the same as the ADAfruit one) - is -
https://www.aliexpress.com/item/3290475 ... y2ES6&mp=1

Out of interest, I would recommend that you possibly try the Adafruit 1306 libraries. they are really great. It is probably a personal thing but I was never overly happy with the UG8 library I find it messy, but maybe that is just me ;)
I always found the Adafruit libraries great. Adafruit_SSD1306, which handles the low-level communication with the hardware, and Adafruit_GFX. Really easy to use and so many options. Worth looking at.
You can use the I2C 4 pin module (as in my pic) without a reset pin defined. When you add the mux for multiple displays (up to 8) you can add a single reset if needed, and you only need to send the data to a single I2C address. Addressing the MUX is a piece of piss with no library required.
It is really great having a choice of all these units so you can fit them to the space that you require.
Joe
Joe. CISSP, MSc.

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