7 segment display Pin outs?

Are you building a cockpit, planning to build one or just dreaming, this is your cockpit builder meeting point

Moderators: russ, Ralph

Message
Author
SimPassion
Posts: 5336
Joined: Thu Jul 27, 2017 12:22 am

Re: 7 segment display Pin outs?

#21 Post by SimPassion »

Kaellis991 wrote: Sun Dec 04, 2022 9:01 pm So the diagram that Ralph posted shows how to wire (2) 3-digit displays to an Arduino?
Why did you mentioned Ralph's example where I already provided the screenshot showing the script part to use
Ralph is correct with the link provided, the screenshot he reported was only showing a MAX7219 sample, as it's written in the page

When we are searching samples or wiring diagrams, the start page is this one (as well for any answer we expect around Air Manager, electronic parts, LUA usage
https://siminnovations.com/wiki/index.p ... =Main_Page

So, in the "INSTRUMENT development" section we find several samples while clicking on "I/O connection examples" https://siminnovations.com/wiki/index.p ... n_examples (@Ralph just seen a typo, the table should mention "Number of characters" as Description for the #3 parameter, I guess it was a copy/paste initially)

However there's no direct sample for the 8 SEGMENT usage, it's a matter of using the available script sample for the 8 Segment usage, which is in text format as shown below, just read at the moment Joe already posted some advice about wiring itself :

Code: Select all

-- Create a new 8 segment based character display with 4 characters
display_chr_id = hw_chr_display_add("NAV1 frequency", "8SEGMENT", 4, "TRANSISTOR_COMMON_ANODE")

-- Set text "1234"
hw_chr_display_set_text(display_chr_id, "1234")

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

Re: 7 segment display Pin outs?

#22 Post by jph »

Hi Gilles, yes exactly, I am merely pointing out that the use of the am api without the transistor option is a non starter and shouldn't really be in the wiki. I got the impression that Kirk thought he could connect multi digits directly without buffer transistors, he cannot. The device. .arduino of any kind....is not capable
The 7219 he has already bought is fine :)
Joe
Joe. CISSP, MSc.

SimPassion
Posts: 5336
Joined: Thu Jul 27, 2017 12:22 am

Re: 7 segment display Pin outs?

#23 Post by SimPassion »

Hi Joe,

I've not made the wiring, however just to watched what's occurs in AM, I've created a check instrument with the script sample and here's what is produced (notice this doesn't show the binding in AM 4.2 Beta 6 though), so there's really the need to put a real 8 SEGMENT sample in the wiki, from the beginning, up to a full working POC including the correct wiring binding to Arduino/AM, in order for new comers to not get wrong expectation :

image.png
 

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

Re: 7 segment display Pin outs?

#24 Post by jph »

Hi Gilles, specifying transistor common anode or cathode would work fine, in theory, as it will be a muliplexed output. If common anode then it would presumably be pnp transistors on each digit .. marked character in the selection menu...from a common supply with a maximum pulse current limit resistor based on the supply voltage and vdrop of the segment..... the dot will be a higher resistance ususally.. the pin on the digit for the transistor (character) would drive the base via a suitable resistor.
The segments and dp would be the sunk via the appropriate arduino pins. Each digit segment of the same letter etc would be commoned together to that pin.
if CA then the would be low side npn drivers and the above is basically reversed for wiring where the arduino sources the commoned digit cuurent but the transistor sinks the total.

To be honest its massively overcomplicated with HAVING to use transistors and resistors. Very messy. The 7219 is far easier.

Joe
Joe. CISSP, MSc.

Kaellis991
Posts: 581
Joined: Mon Sep 07, 2020 8:49 am

Re: 7 segment display Pin outs?

#25 Post by Kaellis991 »

Hey Joe,

As a really simple minded person, I have always been under the assumption that 7 segment displays could be driven with a max7219 IC.
That's why I bought these things about 2 years ago. But I think those two things need to be placed on a board with other stuff...

The wiki page showing the display connection example is written for an 8 digit display that is already integrated with the max7219 on a PCB. And it talks about the pins DIN, CS, and CLK.

I have a smaller .3 in display not on a PCB that I got from Aliexpress back in Dec. 2020 along with the display driver.
So my display and the max7219 are not joined at the hip so to speak and I don't see any wiki pages that shows how the wiring should be done.

I own some of those larger display modules shown on the wiki page, but they are too large for what I want to do. They appear to have some resistors, capacitors and other components on the PCB the 8 digits are mounted to.
Are those the components you are talking about?
Do I need to create a similar board with those components to operate the .3 in displays?




image.png


image.png

Kaellis991
Posts: 581
Joined: Mon Sep 07, 2020 8:49 am

Re: 7 segment display Pin outs?

#26 Post by Kaellis991 »

@simpassion

I have been reading those wiki pages for over two years now. The coding is one thing, but I am trying to focus on the wiring and physical components needed to connect it all. One baby step at a time.

SimPassion
Posts: 5336
Joined: Thu Jul 27, 2017 12:22 am

Re: 7 segment display Pin outs?

#27 Post by SimPassion »

Right Kirk @Kaellis991, the point is I took it at the point you mentioned the 8 Segment wiring without using MAX7219
I will let the discussion going forward on wiring and binding, no issue at all

Kaellis991
Posts: 581
Joined: Mon Sep 07, 2020 8:49 am

Re: 7 segment display Pin outs?

#28 Post by Kaellis991 »

SimPassion wrote: Sun Dec 04, 2022 10:58 pm Right Kirk @Kaellis991, the point is I took it at the point you mentioned the 8 Segment wiring without using MAX7219
I will let the discussion going forward on wiring and binding, no issue at all
No worries....I have always assumed, based on my very limited knowledge, that the driver was required, then I got thrown a curveball when Ralph stated that the arduino can handle the display without the max7219.
So much of this stuff is beyond my brains capacity, though I have learned a few things over the last two years.

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

Re: 7 segment display Pin outs?

#29 Post by jph »

Hi kirk , Gilles, @SimPassion is very kindly pointing out to you the requirements of not using a 7219 or other dedicated driver. He is absolutely correct. AM wiki is absoltely not helpful here and also the section about connecting 8 digits DIRECTLY to an arduino without transistors is simply incorrect and not possible.... Dont shoot the messanger. He has gone way out of his way to help :shock: . I just saw your reply and yes,i do agree that Ralph did toss in a curve ball as the DIRECT connect needs removing from the wiki, connect via transistors is ok, but definitely not direct. No arduino can source or sink the current required for direct connect! :o :?

. Yes, you can use that board you show as the driver board and drive it directly from am. You just need to remove the existing digits, ususally 2 x 4 digit blocks and mark the pinout.. i have the schematic. .they are on the net. , then connect your new units to that using the appropriate wiring and digit connection order as Keith intimated .to AM it will then be a standard 8 digit 7219 module but you willonly be using 6 digits. It is probably as easy to use the ic you bought also. You can use it on bread board as from memory it only needs 2 capacitors and 1 current limit resistor.
The other hardware thing you posted ..i think it was an old com set, that looks fairly.y easy to mod for AM, a bit time consuming but nothing complex or technical as it is just a bank of rotary wafer switches so is simple logic. More on that later as it is late here and i am knackered :) i can offer pointers but you will be doing 90% of any of this yourself. :D

Joe
Joe. CISSP, MSc.

Kaellis991
Posts: 581
Joined: Mon Sep 07, 2020 8:49 am

Re: 7 segment display Pin outs?

#30 Post by Kaellis991 »

Joe,

So rather than build a board from scratch with resistors and other such components along with the max7219 and the (2) displays, you think I can attach these smaller display units to this board if I can find a way to solder them on?
That would certainly be easier....I guess.

But that wont work...the two 3-digit displays will be too far apart.
Also the board that comes with this module is too long.

What I need is a PCB board in a smaller format that does the same thing as this one. The board needs to be about 450mm x 350mm.
I started a schematic in EasyEDA showing the displays and the the 7219 along with a resistor, a capacitor and a diode that seems to be the (3) components I see on that board.
No way that I would know what values those are or if duplicating this board in a smaller format is the correct way to go.....
image.png
image.png

Post Reply