7 segment display Pin outs?

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Kaellis991
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Re: 7 segment display Pin outs?

#51 Post by Kaellis991 »

jph wrote: Mon Dec 05, 2022 1:35 pm I dont understand your issue Keith.

If I want to display 123.987 on the first 6 digits of an 8 digit max7219 module I would simply use
hw_chr_display_set_text(display_chr_id, "123.987")

Why would I be bothering with formatting :shock: ?

(and no, I DEFINITELY do not have any of the propwash 'things' :lol: )
Joe
So the propwash rotary encoder I purchased is crap?

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Keith Baxter
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Re: 7 segment display Pin outs?

#52 Post by Keith Baxter »

Kaellis991 wrote: Mon Dec 05, 2022 1:34 pm
But this takes me back to my question about the decimal point...
Kirk.

Just wire up pin to pin leaving out pin 6

Then manipulate the string as i indicated in the above post.

Actually, what is string format you are using?

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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jph
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Re: 7 segment display Pin outs?

#53 Post by jph »

Kaellis991 wrote: Mon Dec 05, 2022 1:34 pm @jph

Joe,
I have the same 7-segment display shown on the wiki page. Those are .56" tall digits.
My initial plan is to just replace those larger displays with the (2) 3-digit .3" displays I have.
Those 3 digit displays did not come with a board.

If that doesnt work, then I can use the larger 8 digits and create a bezel that will block out the left and right digits leaving only the middle 6 showing through my display window. Although I will still need to detach those two 4-digit displays so I can have them at 90 degrees to the too-long board. The board will need to be installed vertically while the digits will need to be horizontally mounted behind my bezel.

But this takes me back to my question about the decimal point...
There isn't a problem I can see in using the 8 digit driver board for ANY number of digits. The only caveat is that the digits must be common cathode as the 7219 does not support common anode.

What was the question about the decimal point ?

The wiring is really simple. all the segments A B C D E F G and the DP (decimal points) are connected to the same one on the other 3 digit unit.
These all connect to the same lettered 'SEG x' pins on the 7219.
Then you simply have to connect the 'Digit' pins to the correct digit drive on the 7219 and also the 3 digit units.
I can list those pins as well if you like ?
You would just use the D7 to D2 pins and ignore the D1 and D0 - well, that's how I would do it :D
I have no idea at all why Keith is playing around with string manipulation ? - perhaps there is some weird reason ?
Joe
Joe. CISSP, MSc.

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Keith Baxter
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Re: 7 segment display Pin outs?

#54 Post by Keith Baxter »

jph wrote: Mon Dec 05, 2022 1:35 pm I dont understand your issue Keith.

If I want to display 123.987 on the first 6 digits of an 8 digit max7219 module I would simply use
hw_chr_display_set_text(display_chr_id, "123.987")

Why would I be bothering with formatting :shock: ?

(and no, I DEFINITELY do not have any of the propwash 'things' :lol: )
Joe
Joe,

On a standard max 8 digit if you format like so...

Code: Select all

value = "1234567.987"
string.format("% 9.03f",value)
your display would look like so
34567.987

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?

#55 Post by Kaellis991 »

Keith,

So the answer is that I dont use a digit for the decimal and maybe just paint on a little dot between digit 3 and 4?
Or the decimal is part of the 3rd digit from the left?
Then I will only be using 5 of the 6 digits to display 123.45?
The digit display should look like this when all is said and done.

7397C157-5A1B-4AE7-806A-352963AED21D.jpeg
Last edited by Kaellis991 on Mon Dec 05, 2022 1:57 pm, edited 1 time in total.

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jph
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Re: 7 segment display Pin outs?

#56 Post by jph »

Kaellis991 wrote: Mon Dec 05, 2022 1:39 pm
jph wrote: Mon Dec 05, 2022 1:35 pm I dont understand your issue Keith.

If I want to display 123.987 on the first 6 digits of an 8 digit max7219 module I would simply use
hw_chr_display_set_text(display_chr_id, "123.987")

Why would I be bothering with formatting :shock: ?

(and no, I DEFINITELY do not have any of the propwash 'things' :lol: )
Joe
So the propwash rotary encoder I purchased is crap?
No, the propwash 6 digit boards with a 7219 are. The encoders I believe are ok but many report them as being too 'long' - the knobs / controls. They are cheap though.
Joe. CISSP, MSc.

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jph
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Location: Somewhere over the rainbow..

Re: 7 segment display Pin outs?

#57 Post by jph »

Keith Baxter wrote: Mon Dec 05, 2022 1:52 pm
jph wrote: Mon Dec 05, 2022 1:35 pm I dont understand your issue Keith.

If I want to display 123.987 on the first 6 digits of an 8 digit max7219 module I would simply use
hw_chr_display_set_text(display_chr_id, "123.987")

Why would I be bothering with formatting :shock: ?

(and no, I DEFINITELY do not have any of the propwash 'things' :lol: )
Joe
Joe,

On a standard max 8 digit if you format like so...

Code: Select all

value = "1234567.987"
string.format("% 9.03f",value)
your display would look like so
34567.987

Keith
I still have no idea what you are trying to do Keith :)
Why on earth would I be messing with string format ?
To all intents and purposes I send the number to the display as I want it to appear.
If I send 12345678.987 it WILL display 12345678.9
But I would be limiting the number to my available space beforehand if I wanted to.
If I want to display 34567.987 then I would send that to the display. :?
It works perfectly with any combination of digits in an 8 digit original board. I can use a single 4, a 5 or a 6, or 2 x 3 digits, or a 4 and a 2 digit and all I have to do is wire the left to right digits from D7 descending.
Absolutely not an issue, not an issue in the slightest.
Joe
Joe. CISSP, MSc.

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Keith Baxter
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Re: 7 segment display Pin outs?

#58 Post by Keith Baxter »

Guys,

If Kirk is simply going to substitute the two 4 digit LEDs for two 3 digit LEDs. and wiring pin for pin then you have to manipulate the string which is 8 characters long. Do not worry about the decimal point. We can fix that in formatting the code.

If however you want the number of decimals to be RIGHT addressed so that the decimals remain in the same position when a 5 character string is displayed 12.987 on a 5 digit display then you have to wire up and format as I have said.

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?

#59 Post by Kaellis991 »

Keith,

I dont forsee ever having the decimal point in that 12.345 format for a typical freq.

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Keith Baxter
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Re: 7 segment display Pin outs?

#60 Post by Keith Baxter »

Joe,

Most radios have a set 1,2 or 3 digit decimal indication.

What you are doing is LEFT addressing. I understand that and it is true for text and other applications. But not for radios where everything is RIGHT addressed. Some Radios have the option to change the decimals from 2 to 3.

This image shows what I am trying to convey.
ice_screenshot_20221205-161709.png

ice_screenshot_20221205-162158.png
Look at the images in this radio in the link below. You will see that the string "ACARS" is right addressed and that the decimal is consistent 3 characters.
ice_screenshot_20221205-163646.png
https://www.gableseng.com/product/vhf-control/

I honestly do not know how to explane better.

Keith
Last edited by Keith Baxter on Mon Dec 05, 2022 3:37 pm, edited 1 time in total.
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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