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DIY MFD - should I have used shift register - how would it look like?


Jyge

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I got myself a 3D printer and I am in a process of building my own MFDs. I had TM Cougar MFDs but I already sold them. I did not like the feel of them and they were too small for my sausage fingers.

 

 

I also decided that I would like to have a bit more of this and that (rotaries and so on) and I went for a mix of F/A-18, Harrier and A-10C in my design.

 

 

This is a prototype:

9HSW2.png?trs=b491929c24a9bf95c40e4090a4c10e043e2212a47df119bceff68e2f46624812

 

 

 

 

but inside it looks about this:

9HSWB.png?trs=b491929c24a9bf95c40e4090a4c10e043e2212a47df119bceff68e2f46624812 9HSTJSo

 

 

 

I am kind of asking whether I should have gone for shift register(s) instead of diodes and a matrix. I am toying with an idea of designing my own PCBs and ordering them online, so this would be a nice place to try something like that. I have 4 rows and 9 columns matrix with 36 buttons and no axis...In the end I want 3 of those MFDs but I figured I make each one a standalone with an own proMicro-board...

 

 

 

Designing - what software (free) can I use for designing PCB?

 

 

 

I am currently residing in Germany and I found some recommendation in Youtube for a online shop that should work https://aisler.net

is this ok or are there better recommendations?

 

 

 

I am no electrician or so - all I know is that electricity works with smoke - I know that the stuff usually does not work if the smoke escaped the gadget. I would like to reduce the cables, but such an MFD is also rather space limited...at the moment my design is not suited for a screen as my board and so on reside in the middle of the panel. I only intend to use the stuff for VR so it is really not my aim to adapt a screen

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I made a custom PCB using a design on a combination of Solidworks and Qcad, then engraved it on my CNC engraver. I use those SMD switches, soldered onto the PCB, and use top hat shaped buttons that poke through the fascia (in my case made from MDF machined on my engraver, but your 3D printed one would do) to activate them. It's nice and thin (about 6mm) and so I can use a 10.1" LCD screen behind it. I can take pictures if you like

 

But there are plenty of ways to do it, that's just what works for me

 

Cheers

 

Les

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I made a custom PCB using a design on a combination of Solidworks and Qcad, then engraved it on my CNC engraver. I use those SMD switches, soldered onto the PCB, and use top hat shaped buttons that poke through the fascia (in my case made from MDF machined on my engraver, but your 3D printed one would do) to activate them. It's nice and thin (about 6mm) and so I can use a 10.1" LCD screen behind it. I can take pictures if you like

 

But there are plenty of ways to do it, that's just what works for me

 

Cheers

 

Les

 

 

Heh, I am actually starting to build my own CNC with 3D printed parts. Sure would be nice to see a picture, but my main concern was reducing the cabling and perhaps for that end use a shift register instead of a matrix. I am not sure which components I need for a shift register.

 

 

 

I think that I would need four shift registers, one for each "side", then I could do the connections to proMicro with 4 (or was it 5) cables and 5 between each shift register. The downside is that each shift register needs its' own chip (not sure which one it was) and what else I need for one shift register...

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No shift registers on mine, let me get back from work, I'll take it apart and photograph it all

 

Cheers

 

Les

 

 

Yes, d4mn - there is this discussion on SimHQ - it is just well over 100 pages, full of information but I just need one tiny bit...

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Just a question, what do you require of the shift registers?

 

To explain, I run the MFCD's for my A10 setup as one switch going to one input of a Leo Bodnar BBI64 board, so I ended up with about 30 outputs plus the common ground. The bodnar board is directly recognised by Windows and DCS and you simply allocate the button within the control setup

 

Cheers

 

Les

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I'm not sure how a shift register could work.

 

I'm an electronics engineer, so if you have a link to a description, I'll take a look.

 

TBH, the matrix is designed to cut the wiring for a lot of switches to the minimum possible.

 

What you could do is set up so that each side of the display is a "column", and then the individual switches form the "rows".

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I'm not sure how a shift register could work.

 

I'm an electronics engineer, so if you have a link to a description, I'll take a look.

 

TBH, the matrix is designed to cut the wiring for a lot of switches to the minimum possible.

 

What you could do is set up so that each side of the display is a "column", and then the individual switches form the "rows".

 

 

Yes, I am doing the whole mess with the matrix, using the buttons and diodes, but I really can not speak of "reduced" wiring.

 

 

 

I assume that with shift-register I could pack all four sides of the MFD buttons each in its' own register and then chain them up one after another. For the connection between the registers I only need five wires and only 5 to the controller...

 

 

 

I found this discussion and this could lead to something.

 

https://forums.eagle.ru/showthread.php?t=120049&page=5

 

post #46 shows a board for a single shift register I could adapt that...

 

 

 

My idea is to make a PCB for each register, where I can directly solder the buttons - at the moment I do not have any PCBs I only have the buttons directly on 3D printed parts and then connections are done with wires. Of course, I would already reduce the wiring quite a bit if I went to own PCBs for the matrix and packed the buttons and diodes on the plate as well.

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My idea is to make a PCB for each register, where I can directly solder the buttons - at the moment I do not have any PCBs I only have the buttons directly on 3D printed parts and then connections are done with wires. Of course, I would already reduce the wiring quite a bit if I went to own PCBs for the matrix and packed the buttons and diodes on the plate as well.

 

It looks like a precursor to the Bodnar boards.

The have a matrix connection and a break-out available.

And IIRC, they only need diodes if you're planning on more than one button pressed at the same time.

 

It seems to me you're over-complicating something that doesn't need to be.

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DIY MFD - should I have used shift register - how would it look like?

 

The cleanest build I have seen so far is Blue73's MFD. He told me he used a resistor ladder. Way above my skill level.

 

Modular Panel WIP

https://r.tapatalk.com/shareLink/topic?share_fid=74365&share_tid=219982&share_pid=3894967&url=https%3A%2F%2Fforums%2Eeagle%2Eru%2Fshowthread%2Ephp%3Fp%3D3894967&share_type=t&link_source=app

 

 

Sent from my iPad using Tapatalk


Edited by Fusedspine33
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The cleanest build I have seen so far is Blue73's MFD. He told me he used a resistor ladder. Way above my skill level.

 

That's actually a clever idea.

You read the whole keyboard with a single analogue input as though it's a potentiometer.

 

The simple ones only work properly if you press one key at a time, but you can make it read more if you use different resistor values.

It'd probably work well for an MFD.

It could reduce the wires from the "keyboard" to 3 - two for power and one to the analogue input of the arduino.

 

Have a look here:

https://electronics.stackexchange.com/questions/331661/resistor-ladder-with-same-resistor-value-and-different-resistor-value

 

And here:

https://electronics.stackexchange.com/questions/331661/resistor-ladder-with-same-resistor-value-and-different-resistor-value

 

 

I'd think the tricky part would be sending the appropriate signal to DCS.

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Shift reg is the best, precise, no shadow, simultaneous press, easy coding, easy expanding by chain...

Beside VCC/GND, only 3 wires for CLK/DAT/CS, and they can be shared in some design, save a lot of MCU pins.

 

For PCB drawing, you can try KiCad, it's free and not bad.


Edited by jayyang
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Hi, I'm also an electronics engineer :) For an MFD do you need to simultaneous press two buttons at once? If not then go the resistor ladder solution. If you want any help I can send you my code. Never had any issues using it, rock solid.

 

cheers

 

John

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