Challenger 300 FMC CDU

[ame]

Since I have nothing better to do (!) I am plodding on with an FMC CDU design for a Challenger 300 that I started ages ago. If anyone is interested that's great, but if not that's fine too.

I have the idea that this device should be nothing more than a display and a keyboard. The display plugs into a PC like a monitor, and the keypad plugs in like a keyboard. Thus, all the smarts are elsewhere.

So I have a 5" VGA monitor and driver, off the shelf. And I'll make a PCB with tiny pushbuttons in the right place, hooked up to a PC keyboard driver chip (such as Holtek HT82K629A) or an Arduino Pro Micro running QMK firmware.

The keypad will plug in like a regular keyboard. Keys A-Z and 0-9 will generate those key codes. The 12 function keys (6 left and 6 right) will be F1 to F12, and all the other keys will generate some other key press, probably ! to ) on the top row, above the number keys. No shift, ctrl, or other keys.

I have 3D printed a panel for this, and some actuators for the buttons. The technique I am using could be used for any FMC for any plane. It's still a work in progress, so don't hold your breath.

Edited to add: The gray panel is an early prototype, without the rebate for the VGA display module. The white panel is the top 2/3rds of the current design with the VGA rebate. My printer is quite small, so I have to print the panel in four parts and glue them together. I also have to print the actuators, and make sure they move freely. I'm not sure about the decals yet...

[Joe Lavery]

Ame,

An interesting project indeed!

I notice you always display your images twice in each post.

Trevor has referenced this issue at the beginning of the forum header.

If you just click upload on your attachments. you will get a single insertion, if you then also click insert you get them twice.

Cheers
Joe.   

[ame]

Yes, I wondered about that. The upload has an 'insert' button next to it. It seemed to me that uploading was one operation, then deciding where to put it was another.

I wonder if there is a forum administrator option to show/not show uploaded files next to their associated post.

[Trevor Hale]

No there isn't but if you click upload, don't click insert.  Its better with the attachments on the bottom of your post regardless, otherwise the forum can look strange.

Trev

[ame]

Roger wilco.

I edited the post to remove the references to the images, so they only show up once. And I edited this post to say that I had edited the other post.

[ame]

Just a small update. I printed the rest of the frame, and glued it together. I'm pretty happy with the switch openings and actuators, but I need to make a slightly more permanent test assembly.

When I build the 3D model I print out the coordinates of the centres of the switches, which I hope to import into Kicad for the PCB design. Then everything will line up.

The switches are tiny SMD tact switches, 6x6 mm and 3mm tall. The fascia is 6mm tall, so I open a 4mm cavity for the switch body then the actuator has a 0.7mm flange (to stop it going through the aperture) and a 4.3mm body on top (so it sticks out by 2mm). It really is pushing the capabilities of the printer, but it does work (especially after a spot of filing or some sandpaper).

I also hooked up the 5" VGA module. That works too, and looks pretty smart. It is a ZJ050NA-08C display module and KYV-N2 V6 display driver board. These are available as a pair from the usual sources for about $40 or so.

[ame]

So, on further research the Holtek HT82K629A is probably not going to work for me. It seems to be targeted at a compact keyboard, so F11 and F12 are not directly available, they are only accessible if you hold an extra key down (Fn) first. Much like a laptop keyboard. Some other keys I wanted to use are also not available directly, so I will put that chip to one side.

That means I will probably use an Arduino Pro Micro and build a QMK keyboard. I will get full control of the key matrix, but it will be USB only. I might be able to make a PS/2 version too, but code for that seems to be less common (since, of course, you can just buy an HT82K629A...)

[ame]

I pulled the pin on the PCB design and sent it to JLCPCB. If everything goes well then the PCB will match the 3D printed fascia, and the VGA panel will drop right in...

[ame]

And the boards arrived today!

Attached is a photo of the prototype 3D-printed fascia on the unpopulated PCB, with the 5" VGA panel installed. Surface-mounted switches will be soldered at each key position, and actuated by a 3D-printed keycap. The switches form an 8x9 matrix, which is accessible via a 20-way 0.1" header on the reverse.

I have the switches, but I am waiting for the diodes and header to be delivered. And I need to find someone with a bigger 3D printer than I have.

The display is currently connected to a Raspberry Pi Zero through an HDMI to VGA converter. The Zero has a single USB port and no networking, so I have plugged in a 3-port USB hub and Ethernet adapter. This allows me to connect an Ethernet cable and keyboard.

[bernard S]

i have huge resin printer 293 x 165 x 400mm     need to figure out how it works

[ame]

i have huge resin printer 293 x 165 x 400mm     need to figure out how it works

Cool story, bro.

[ame]

It turns out that diodes in an SOD-323 package are really small. I need to make some notes about changes I should make to the PCB, so I'll start here and suggest (to myself) that I should choose a bigger diode package. I might also tweak the locations of the function keys to the left and right of the screen. And it would be nice to have headers that an Arduino Pro Micro could plug straight in to, but for now I have made an adapter. That's enough for now.

I've soldered all of the switches, and the diodes, and the 0.1" header. Next step is to program the Arduino with QMK firmware, then the FMC will plug in and behave just like a USB keyboard.

[ame]

It works!

I have an Arduino Pro Micro that I have programmed with QMK firmware. It looks like a keyboard when plugged in to a PC, which I have tested on a Raspberry Pi and a Windows 7 laptop. The Arduino scans the rows and columns of the FMC keypad and generates keypresses just like a regular keyboard would.

At the moment the FMC generates a-z 0-9 and F1-F12 for the obvious equivalent keys. EXEC generates Enter, PREV/NEXT generate Page Up, Page Down, and the other FMC keys generate other keys that could be detected by FMC software. It is easy to redefine which keycodes are generated when a key is pressed.

So, to recap, I have built a hardware FMC with a 5" VGA display for output and a USB keyboard for input. The display is driven from a Raspberry Pi by an HDMI-to-VGA converter, and the keyboard is plugged in to the Pi. Currently it is essentially just a Raspberry Pi, with a small display and a custom keyboard. The next step is FMC software that fetches data from the simulator to display on the screen, and sends keypresses to the simulator.

[ame]

A couple of new pictures now that I have my Creality Ender-3 V2 working. The frame takes about 7 hours to print, and the keycaps about 5 hours. I was able to assemble everything with very little post-printing work. If I had the right filament (I ordered "grey" and got "very light grey") I'd be done. As it happens I'll have to paint everything, which I may have had to do anyway.

The keycaps with legends look terrible. I'll print some blank ones and figure out how to put lettering on them. Otherwise, it all works.

[Mach7]

Andrew, those prints look amazing...question for you....how do you like the Ender-3 unit? I have a Creality 10s but am finding a lot of problems with it as it gets older...like the interface rotary knob will sometimes create a situation where you cannot get any information on the (mono) interface panel.

Also have tried to clean the nozzles, but am finding I have to increase the temperature to allow the PLA to flow properly...(went from 200 to 220, not printing at 235 degrees).

I am looking to upgrade..

[Trevor Hale]

@Mach7.  I had a similar problem with my Printer and finally found out the issue.  In order to get the nozzle hot enough, I had to set the temperature way higher than I had use to have to set it.  So hot to the point the Pla was melting inside the block and struggling to make it to the nozzle without clogging.

Here is what I had found.

after removing the nozzle many times to try to clean etc, I realized the nozzle wasn't tight against the block and the threads of the nozzle wern't conducting heat as well as if the nozzle was tight against the block.  With your block removed, ensure the nozzle is tight all the way to the block, then thread in the top collar/tube.  after I did this, the issue of having to raise the temperature to like 240 to print where I would normally print at 210 was gone.

Trev

[ame]

Andrew, those prints look amazing...question for you....how do you like the Ender-3 unit? I have a Creality 10s but am finding a lot of problems with it as it gets older...like the interface rotary knob will sometimes create a situation where you cannot get any information on the (mono) interface panel.

Also have tried to clean the nozzles, but am finding I have to increase the temperature to allow the PLA to flow properly...(went from 200 to 220, not printing at 235 degrees).

I am looking to upgrade..

G'day. I have owned the Ender-3 V2 for one weekend. I wouldn't suggest it was an upgrade, as it's the entry-level offering from Creality. The 10s is supposed to be better.

Having said that I am very happy with it. It is nicely put together, and it works. I am not stretching its capabilities, but I am happy to be able to design something (in OpenSCAD) slice it (with Cura) and trust the machine not to screw up during the 7 hour print time. Since my previous printer was small (not a Creality) most of the jobs were relatively short, so bigger (and longer) jobs need me to feel confident about the machine.

I did spend some time levelling the bed, and fiddling with temperatures. With the current filament I am using 65 for the bed and 220 for the nozzle. Seems fairly consistent now.

I'd expect there to be an active community around the 10s, where you could get advice on tuning it up again. Your interface panel problem could be caused by a bad rotary encoder, which should be easy to replace. You might also find that there is new firmware that improves things.

I've had my old printer for over three years, and I'm still happy with it. They are very simple machines which should keep going.

[Mach7]

@ Trevor, yes...i had the same problem when I replaced the nozzle with the new (supplied) one. I found that I had not tightened it very well to the hot end and the PLA extruded around the threads.

These Creality machines are great and cheap, but i what saving I saved by purchasing one of these machines is offset by the amount of PLA I have wasted trying to get a good print.

Also finding that the roller wheels wear down quite rapidly...if you notice the black tread that wipes off on your hand when you touch them seems to be worn off rubber.

In all I have made some pretty satisfying prints...but it always seems to be a struggle with these machines, whether it be print adhesion, leveling, or nozzle issues.

[Joe Lavery]

I've had an Ender 3 (standard model) for nearly three years. Over that time I have made literally hundreds of prints with it, some for my own use and some I have sold.
I have never had an issue with bed levelling and my prints stick fine using a Printbite printing sheet.
My gantry wheels are as good as the day I bought the machine and I've only used two nozzles since I bought it.
Like most folk I bought a pack of 10 Nozzles, 10 spare wheels, a new hot end and a length of the Capricorn blue filament tube. All these are still in the box they arrived in.
I may have been lucky I guess, the only thing I do is keep it clean and adjust the bed springs with a gcode file I downloaded from Thingiverse once every couple of weeks.

I think for the price it's an amazing little machine. If it failed I would buy another one. However, last year I bought a Elegoo Mars Resin printer, which is great for things like knobs and small items that need to be more defined.

Joe.