7 segment display Pin outs?

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jph
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Re: 7 segment display Pin outs?

#212 Post by jph »

Joe. CISSP, MSc.

SimPassion
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Re: 7 segment display Pin outs?

#213 Post by SimPassion »

jph wrote: Mon Jan 30, 2023 9:29 am Hi Gilles
https://siminnovations.com/forums/viewt ... lit=tm1637

Joe
Nice thread I've missed, thanks for the head up Joe ! 👍 Just bookmarked this one !

Kaellis991
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Re: 7 segment display Pin outs?

#214 Post by Kaellis991 »

These may work better. Max 7219 board. No clue about the quality yet.

IMG_6342.JPG

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Keith Baxter
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Re: 7 segment display Pin outs?

#215 Post by Keith Baxter »

Hi,

Yes that will work but will need some tweaking with code to make it work. The FACT that AM addresses from the left and chip manufactures address from the right will result in the first two digits in your string not being displayed because the D5 to D7 on the MAX7219 chip and not connected to a display led.
This would also mean that you would would have to reverse the string because a string of "HELLOW" would return " WOLL"

This is a issue I have bashed with many here @Corjan and hopefully will gain appetite for a rethink in how AM handles shift registers.

Here is a quick search of the board you mention which gives a schematic of the board you talk to. I will look for the schematic for the common 8 digit board that AM supports. But it is reversed to this one. This 5 didst board is correct to the MAX7219 specifications.

https://protosupplies.com/product/max72 ... lay-board/

Keith
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SimPassion
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Re: 7 segment display Pin outs?

#216 Post by SimPassion »

Kaellis991 wrote: Wed Feb 01, 2023 9:32 pm These may work better. Max 7219 board. No clue about the quality yet.
Keith Baxter wrote: Wed Feb 01, 2023 9:56 pm Hi,

Yes that will work but will need some tweaking with code to make it work. The FACT that AM addresses from the left and chip manufactures address from the right will result in the first two digits in your string not being displayed because the D5 to D7 on the MAX7219 chip and not connected to a display led.
This would also mean that you would would have to reverse the string because a string of "HELLOW" would return " WOLL"

This is a issue I have bashed with many here @Corjan and hopefully will gain appetite for a rethink in how AM handles shift registers.

Here is a quick search of the board you mention which gives a schematic of the board you talk to. I will look for the schematic for the common 8 digit board that AM supports. But it is reversed to this one. This 5 didst board is correct to the MAX7219 specifications.

https://protosupplies.com/product/max72 ... lay-board/

Keith
Nice find !! 👍

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Kaellis991
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Re: 7 segment display Pin outs?

#217 Post by Kaellis991 »

@Keith Baxter

Hey Keith,
When I previously setup the (2) 3-digit displays to connect to the 8 digit display board, I had to swap some pins around on the left display (6 to 8, 8 to 9, and 9 to 12) while on the right display pins 6 and 8 were left unconnected.

For this Protoboard and the 5-digit display there are a total of 14 pins.
I need to mount the 5-digit display to a small transition / breakout perfboard of my own making with pins that I can use to connect a short cable harness to pins I will solder onto the Protoboard.

When making the connections from the 14 holes on the Protoboard to the 14 pins on the display will all of these connections just be a 1 to 1 correlation as in the image below?
Any need for swapping pins around this time?

image.png

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Keith Baxter
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Re: 7 segment display Pin outs?

#218 Post by Keith Baxter »

Hi,

@Corjan for your info.

The board previously discussed in another thread and this one are like comparing a chicken and a rabbit.

1) AM (at this time) addresses chars from the MAX7219 from left to right... D7,D6,D5,D4,D3,D2,D1,D0. This is understandable because the most common 8 digit MAX7219 displays are on sale on line.

2) However the MAX7219 is not designed so and should be from left to right... D0,D1,D2,D3,D4,D5,D6,D7. This is what the boards we discuss are all about. They are true to index shift registers and handle the voltage instability.

Issues come into play when formatting strings for display when it comes to different shift register types.
Corjan.. when writing code one should not have to bother about what shift register one is using. Debatable res, but a coder has no idea on what hardware a user is using.

Lets look at a simple string.The two different wiring produces different results
Example 1
In 1) A string of "12345678" will display "12345678"
In 2) A string of "12345678" will display "87654321"

Lets look at what happens when the string is shortened. I use the # as a white space within the 8 digit display
Example 2
In 1) A string of "1234####" will display "1234####"
In 2) A string of "1234####" will display "####4321"

Now lets reverse the string in (2)
Example 3
In 1) A string of "1234####" will display "1234####"
In 2) A string of "4321####" will display "####1234"

Now lets look at 5 digits. Rem that (1) will be wired D7,D6,D5,D4,D3 and (2) will be wired D0,D1,D2,D3,D4 from the MAX chip
Example 4
In 1) A string of "1234" will display "1234#"
In 2) A string of "1234" will display "####4"

And if you reverse the string in 2) you will get
In 2) A string of "4321" will display "####1"




What have we learned from this? We learned that AM addresses the MAX7219 digit output from left to right in the order of D7 to D0.

How can we fix this? Hopefully Corjan can come up with his magic once again. ;)
For now, using these boards would require some smart coding in formatting strings.

These boards look like the answer for MCP and radio use. Possibly more than 4 can be daisy chained due to the voltage handling.

Keith
Last edited by Keith Baxter on Sat Feb 04, 2023 12:20 am, edited 1 time in total.
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Kaellis991
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Re: 7 segment display Pin outs?

#219 Post by Kaellis991 »

What does all that mean for my wiring harness?
And will I be able to find someone that can help me with the "smart coding" if even possible?

Or is this just a dead end also?

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Keith Baxter
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Re: 7 segment display Pin outs?

#220 Post by Keith Baxter »

Kaellis991 wrote: Fri Feb 03, 2023 10:10 pm What does all that mean for my wiring harness?
Hi,

I seem to not explain so that you understand. Not your fault, i am not good at getting my point across most times. :oops:

I am sure @SimPassion can explain in another way that you can understand.

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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