3D Model for 5" display?

[John Nicol]

BTW, I found these right angled usb connectors that might help with routing the power cable if you need to. Obviously if it is behind a panel it isn't critical, but provides options.

https://www.amazon.ca/Startech-Com-UUSB ... 846&sr=8-7

[Snowflake6]

BTW, I found these right angled usb connectors that might help with routing the power cable if you need to.

I was just looking at right-angle cables online... But i'm using a Pi4 (right now, anyway) and it's USB-C. I'll see what I can find.

You could also potentially just mount buttons and rotary encoders in their own separate bezel anywhere on the panel. I have done this as well on another prototype I built.

Is there information somewhere on adding buttons/encoders to the Pi for this? I'll take another look at the GitHub. Being able to use this without a keyboard would be a good start, so having buttons for previous/next screen at least would be a start.

[John Nicol]

Yes, I have an arduino pro micro that I set up using a matrix. It is a bit involved, but I need to document it. I was using QJoypad to do it, but it is a PITA to use and I am not a coder. I was looking at some python code that I found to bypass the QPadjoy requirement. I got bogged down with other things but I will post what I learned so that others may have a look. Give me a couple of days to get organized on that.

I know that Phil has some code in there to use encoders and buttons directly, but I haven't followed through with that either....

[Snowflake6]

Sounds good. Third revision of the case is now on the printer, i've optimized fit quite a bit, added holes for brass inserts for mounting to a panel, and just today I added provision for a 30x30x12 fan to help keep the Pi running a little cooler. Fan mounted in the dead space at the SD card end of the board, and vents out the top of the case towards the USB port end. That should force air to flow over the Pi board between the vents and the fan.

Will add some photos once both parts are printed.

[John Nicol]

Awesome! Look forward to seeing the results.

[Snowflake6]

Updated case model with fan added. This was a 30x30x12mm, 5Vdc fan that I happened to have sitting around. I think a better solution would be to mount a 35x35x10, for increased diameter and reduced thickness, but I didn't have one handy. Added to my Digikey ordering wishlist, when I get it to the free shipping threshold i'll order one...

Fan is wired directly to the bare pads next to the (occupied) Raspberry Pi header(*). It would be great if this header was populated with a pin header like on the Pi. It would allow for a lot of expansion options, even direct connection for GPIOs.

(* an astute reader would notice that the 5Vdc fan wiring carefully avoids the clearly marked 5V pads. This is a common trick used to reduce fan noise on permanently-connected Raspberry Pi fans, by connecting a 5Vdc fan to the 3.3Vdc terminals instead...It turns at a lower, quieter RPM)

[John Nicol]

That looks great! Also, yes we are indeed working on a connector for those pads. Kyle is designing a board now so that we can add extensions so that it can be as low profile as possible. First up is a CAN controller. More to follow on that. Well done on using those pads though for the fan.

Today is "get my 3D printer working again" day. Ground hog day in other words. My CR-10 has performed great for the past few years but I think I have replaced everything at least 2 or three times. I look forward to trying out the new case design.

[Snowflake6]

One larger issue that still needs to be addressed is power. The MicroUSB (or USB-C) connector is not a reliable connection for a flight instrument.

The Pi has test pads near the USB connector that are large enough to solder to, and could be used for voltage input. Some of the Stratux guys are using them for a more permanent installation. The benefit to this over just jacking into the Pi header (which works) is that the header bypasses the protection circuitry that comes with the USB input.

I've been meaning to try and get Vern thinking about a more robust power supply for the Pi, that could be fed from the 12Vdc bus on the airplane. There's a fair bit of space in the case (in the area where the Fan is), a custom power board could be fit into there and added to the header to provide a more robust source.

[John Nicol]

Agreed. We have already got something in mind. Kyle is working on a connector board that takes advantage of the pads on the screen. Here is what we are thinking of:



It will provide the ability to connect devices to it and they could be anything, including power. We are looking at a CAN interface initially.

[Snowflake6]

The board on the screen is your custom design, isn't it?

It would be better if the connector could be incorporated on that board instead... Along with power circuitry. There's a lot of unused space on it.

A related question: Is there a reason the display couldn't be driven from the display header on the Pi, rather than through the bulky HDMI connector?