7 segment display Pin outs?

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Keith Baxter
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Re: 7 segment display Pin outs?

#31 Post by Keith Baxter »

Kirk,

Using the MAX7219 board and replacing the 4 digit displays with 3 digit displays is possible because pin 6 on the display is the 4th digit. All other pins are the same. You will have to take that into account when you format the string.

A string 12345678 would show 123567

But if you are building a com radio from scratch. Here is a circuit diagram.
Com Radio Boeing 737.pdf
(283.75 KiB) Downloaded 47 times
Keith

EDIT: As has been mentioned before. You can use the 8 segment option. However you will end up using 14 pins on your Arduino where as using the MAX7219 only 3 pins on the Arduino. When you have 7 radios in a stack (200 pins) there is a big saving on Arduinos. ;)

I use these by the way
https://www.aliexpress.com/item/1005003 ... 63edS1cI43
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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Joined: Mon Sep 07, 2020 8:49 am

Re: 7 segment display Pin outs?

#32 Post by Kaellis991 »

Joe, thanks for that schematic.
A lot to unpack there.
1. Two max7219s ?
2. Only four digits....what about the 5th digit or 6th digit?
3. There are other things in that schematic that I dont need

The diagram that @ralph posted shows pins 12, 9 and 8 for digits 1,2 and 3. Pin 6 has a NC which I assume means not connected unless there is a secnd display whose digit 1 becomes digit 4 by connecting pin 6 on the first display to digit 1 on the second display.
How does digit 5 or even 6 get into the mix? Are all 6 digits used such that digit 4 (which is digit 1 of the second display) becmes the decimal point?

3am here and I need to go to work today....but just cant resist the torture of trying to decipher all of this.

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Keith Baxter
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Re: 7 segment display Pin outs?

#33 Post by Keith Baxter »

Kirk,

The MAX7219 board that you have has 2 LED 4 bit display
ice_screenshot_20221205-103539.png
By removing the 4 bit and replacing replacing it with a 3 bit, The 4th and 8th digits will be missing.
ice_screenshot_20221205-103653.png
People have done that conversion. But as I say. The string format needs to be twerked.

Note that by removing the 4 bit and replacing the 3 bit you will have a gap as shown in the top of this image.
The bottom of the image shows no gap but you will have to custom wire yourself.
IMG_5609.jpg
That schematic is for two 6 digit displays. I will do a few schematics just for 3,4,5,6,7 and 8 digit using a MAX7219 IC

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 

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Keith Baxter
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Re: 7 segment display Pin outs?

#34 Post by Keith Baxter »

Hi,

This is just for 1 MAX7219 6 digit display.
MAX 6 digit.pdf
(134.12 KiB) Downloaded 51 times

This one is for 1 MAX7219 5 digit display.
MAX 5 digit.pdf
(121.2 KiB) Downloaded 59 times
I will do the others when I have a bit more time.

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?

#35 Post by Kaellis991 »

Joe,

Thanks for going to all that effort.
Back a couple years ago I was working on a transponder (i might resurrect that some day) and had re-wired an 8 digit module to add a larger gap between the two displays. In fact, I even had a custom PCB board made to spead those apart. Before that I had used some wiring harnesses but it wasnt as elegant as I wanted.
So I have the experience to figure out how to get those two displays closer together.

If I can find that PCB file on my computer I can revise it. But its been so long ago
DD60A36C-118D-461F-878A-DB15681795D6.jpeg
I dont remember right off hand which of the 4 or 5 ECAD programs I used.

But I can also take some perfboard and create a module based on the schematics you have provided. Just have to use wires for the traces.
Or I can try to relearn one of the ECAD programs that I havent work with in a long while and create a board I can send off for manufacture. I cant remember where I had that PCB made. Its a popular PCB manufacturer that I found but cant remember the name right now.
Still a question I have about the frequency dispay is do you use a digit to display the decimal, or just make a little dot somehow between the two displays?

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Keith Baxter
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Re: 7 segment display Pin outs?

#36 Post by Keith Baxter »

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 

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jph
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Re: 7 segment display Pin outs?

#37 Post by jph »

Hi Kirk, it is Keith who is supplying schematics - not me.

Also, please note -

Keith, a few pointers.
Your rSet is WAY too high. It needs to be around 10 to 15K. The display would be far too dim. Set the rSet at 10 to 15 K and use the standard dimming function.
I pointed this out to you in the past also. Refer to the datasheet.

Also your digit ordering hence your schematic is also incorrect.
With AM, the leftmost digit of a display - for example, an 8 digit display, is connected to D7 on the Max7219

If you were using 6 digits, then if we call the actual digits - from left to right 0,1,2,3,4,5
then the connection to the 7219 would be D7,D6,D5,D4,D3,D2 respectively.

D0 and D1 would be unused.

------------------------------------------------------------
edit - On another note for Kirk, I wouldn't bother with a PCB for this. Simple breadboard is fine. Too much hassle :)
Joe.
Last edited by jph on Mon Dec 05, 2022 12:25 pm, edited 1 time in total.
Joe. CISSP, MSc.

Kaellis991
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Re: 7 segment display Pin outs?

#38 Post by Kaellis991 »

I am sorry about getting you two mixed up. Working on my iPad I sometimes dont see the name and make assumptions.
Keith,
Thank you for the schematics. Since I have received most of the hardware info from Joe in the past, somehow I got confused and I just made that assumption and of course you know what they say about assumptions...I can be pretty dense.

Kaellis991
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Re: 7 segment display Pin outs?

#39 Post by Kaellis991 »

Keith Baxter wrote: Mon Dec 05, 2022 11:50 am Kirk,

I use
https://easyeda.com/page/download

Keith
Keith,
I worked with EasyCad yesterday. It seemed to be easier to find the components I needed.
Fusion 360 is a program I have a license for but I have had some issues with figuring out the libraries.

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

Re: 7 segment display Pin outs?

#40 Post by Kaellis991 »

I need to pay more attention to the avatars since I gloss over the names so easily.

Some good options to ponder between the path of least resistance and the learning experience.
Thanks to all for the help and to you Keith for the schematics...

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