7 segment display Pin outs?

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Kaellis991
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Re: 7 segment display Pin outs?

#221 Post by Kaellis991 »

Keith,
Previously for the 6 digit display you explained it very well what pins needed to be swapped / rerouted.
I was thinking you would know if something similar needed to be done for this 5 digit display or not.
Just looking to know if I can connect straight through from Protoboard to display pins.

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Keith Baxter
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Re: 7 segment display Pin outs?

#222 Post by Keith Baxter »

Kaellis991 wrote: Fri Feb 03, 2023 10:33 pm Keith,
Previously for the 6 digit display you explained it very well what pins needed to be swapped / rerouted.
I was thinking you would know if something similar needed to be done for this 5 digit display or not.
Just looking to know if I can connect straight through from Protoboard to display pins.
Hi,

If you are going to use these boards then nothing needs to be swapped wiring wise. No matter if you use 3,4 or 5 digit displays.
However, the way AM currently handles the MAX7219 register, it is skewed from normal. The code has to be manipulated and is a challenge.
Do not be discouraged. It can be done, although a bit messy right now until @Corjan does his magic. I would be far more comfortable using these boards than the other ones. They are more stable.
Normally MAX7219 chips cannot be reliably driven directly by 3.3V logic due to their higher than normal minimum logic high voltage (Vih) requirement of 3.5V. These modules include a 74HCT125 logic level buffer chip to drive the MAX7219 correctly from either 3.3V or 5V logic. This buffered signal is also passed to the loop-out connector for connection to other display modules so the MCU only sees one signal load.

The modules include reverse power protection diodes on each module. The loop-thru power does not include this diode drop to allow multiple modules to be daisy-chained together mainly limited by the size of the wiring used between modules and the size and brightness of the displays used . For longer daisy -chains, the power can be connected at several points in the chain if needed.

The power input includes a 10uF tantalum and 0.1uF MLCC capacitors at the chips to minimize voltage fluctuations during display operation.
These boards will most likely become the boards of choice for cockpit builders as they are compact and adaptable IMHO.
It is just the swapping of the current AM MAX7219 register that AM needs to address so that coding is consistent.

Keith
AMD RYZEN 9 5950X CPU, Corsair H80I cooler, ASUS TUF GAMING B550-PLUS AMD Ryzen Mother Board,  32Gb ram Corsair Vengeance 3000Mh, MSI GTX960 4G graphics card 

Kaellis991
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Re: 7 segment display Pin outs?

#223 Post by Kaellis991 »

Keith,

Thank you for that.
So I guess I can wire them up and hope I can find someone to do the messy coding as I wouldn't have a clue about that...or I can stay with the more unstable ones that I have that are coded already.

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Keith Baxter
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Re: 7 segment display Pin outs?

#224 Post by Keith Baxter »

Kaellis991 wrote: Fri Feb 03, 2023 11:57 pm Keith,

Thank you for that.
So I guess I can wire them up and hope I can find someone to do the messy coding as I wouldn't have a clue about that...or I can stay with the more unstable ones that I have that are coded already.
LOL,

You know who that "someone" is. :lol:

But the fact remains that the SI guys need to take note and help make things easier.

Keith
AMD RYZEN 9 5950X CPU, Corsair H80I cooler, ASUS TUF GAMING B550-PLUS AMD Ryzen Mother Board,  32Gb ram Corsair Vengeance 3000Mh, MSI GTX960 4G graphics card 

SimPassion
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Re: 7 segment display Pin outs?

#225 Post by SimPassion »

I will try tomorrow to resume the thread of the discussion, not had time yet to follow the whole latest sharing.
Hope meanwhile, Kirk get the module fully working !

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jph
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Re: 7 segment display Pin outs?

#226 Post by jph »

Hi guys
firstly there is nothing at all wrong (imho) with the way AM handles the 7219 in an way. Any needed conversion can be coded in lua. There is no 'standard'.
secondly, whilst those displays seem ok - and maybe ok - for the instrument you have Kirk - due to the large lettering on the original drum wheels, 0.36 is generally too large for other realistic displays. 0.28 / 0.3 is far better and vastly different in physical size.
if you can fit the standard 8 digit units behind your panel and just use certain digits then that is a great solution and easy.
or still use the 0.2x units and hard wire them as I said before. from the perf board with the displays on you only need 13 small wires for 5 digits and 14 for six.
Joe
Joe. CISSP, MSc.

Kaellis991
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Re: 7 segment display Pin outs?

#227 Post by Kaellis991 »

Hey Joe,

Thanks for the input...

In all my searching I can't say that I have ever seen a .28" or .3" high display. At least anywhere other than Aliexpress which I really dont want to purchase from.
There is a .28" display at Jameco, but it is a 4 digit clock display.

So I think I have narrowed it down to the options shown.
The .2" seems to be close enough in height but the digits are spaced quite far apart.
Using the 8 digit detachable display board with those (2) 3 digit displays has been a rather unstable solution.

That led me to look at the standard .36" 8 digit display module with the display soldered on the board. It's a possibility if I cover the unused digits with my bezel frame.

However, I then discovered the 5 digit display which has a slightly narrower font footprint than the double 3 digits and the standard 8 digit module.

So weighing the options I have, I am finding that the 5-digit ones give me a good compromise factoring in all the issues.
They dont need to be exactly like the rotary digits. Those digits are very compressed in the width.

I think the 5 digit display with a board designed for it may be more stable and something I can live with.

Kirk

IMG_6366.JPG
IMG_6367.JPG

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jph
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Re: 7 segment display Pin outs?

#228 Post by jph »

Hi Kirk,
can you please provide actual dimensions of the display area on the panel of the instrument ?
To me, ALL those displays look a little too large for the cut-out area.? - probably an optical illusion :)

I am sure I can find some 5 digit displays in 0.28/0.3 and can happily send you a couple to experiment with.
First you need to check the measurements.
Check the images and measurements in this thread - https://siminnovations.com/forums/viewt ... it+display
Let me know if the size looks good ? - I can send you a couple of the 0.3 x 5 digit.
You would still need to hardwire them to a stock 7219 controller board as you have but that is no biggie. 13 wires per display - only needs to be done once :)
Joe
Joe. CISSP, MSc.

Kaellis991
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Re: 7 segment display Pin outs?

#229 Post by Kaellis991 »

Joe,

My panel is just laser cut 6mm plywood with a 1.59 mm ABS facing glued to it for that matte black finsh.
The frame around the perimeter of the entire unit is made with my 3d printer and PETG filament. (Not shown in the above pic)

I dont have a CNC machine to cut acrylic so I use woodcraft here in town to laser cut the plywood and then use it as a template to router the ABS with a flush router bit. The woodcraft laser cutter can't cut the ABS without melting it and producing cyanide gas.

The opening in the ABS for the display was designed for the .2" display in my cad program.
This panel is easy to redesign and re-cut with larger openings. In fact I have already started a redesign in cad based on the Protoboard. But if the .3" display is an option I can redesign again.

So whatever display I go with, I will just design my panel around it.

If you can find the .3" displays, without me having to resort to Aliexpress, that will be another option.
But I have to consider if it is worth all the re-design to change the display height by 1/16". (.36" down to .30")

Edit; I can take what I have and just use a utility knife to cut the opening larger. I am using a 3D printed bezel insert that will hide a less than perfect rectangular opening.
The biggest debate I am having with myself right now is how to mount and wire the displays, the circuit boards and my arduino to the back side of that panel.
Kirk

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jph
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Re: 7 segment display Pin outs?

#230 Post by jph »

Hi Kirk,
I thought you were using the original panel from the hardware ?

It would be better - and fun - to make the original hardware work with AM. pretty easy too.
it's only a (probably) bcd output per digit so 4 pins per digit. - a single mega or pico with mux units would sort it :)

If you are using a home made front instrument panel for the comms than you can use anything of course. - in the way of digits.
I am happy to send you a couple of 0.3 x 5 digit units if you need them though.

Joe
Joe. CISSP, MSc.

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