Is there a smarter way?

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maxdha

Joined Dec 3, 2023
15
Hi, I'm working on a project that involves displaying the following words on three 7-segment -displays.

1. A S U
2. F O E
3. C S E
4. F U N


Each word should transition to the next after a one-second interval.

I made it by creating a truth table for each display and implemented it using logic gates. For instance, inputting 00 to the 3 displays results in showing "A S U," inputting 01 shows "F O E," and so on.

I showed that to my professor and he was fine with it (That's how most students did it). However, I believe there might be a more efficient, less cluttered approach. All suggestions would be incredibly valuable to me, especially since this is my first experience with electronics!


Here are my circuits, where each display has a set of characters:
1701815730572.png

1701815746179.png

1701815764142.png

And here's how the 3 displays should change every second:
1701816304889.png
 
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dl324

Joined Mar 30, 2015
16,716
I showed that to my professor and he was fine with it (That's how most students did it). However, I believe there might be a more efficient, less cluttered approach. All suggestions would be incredibly valuable to me, especially since this is my first experience with electronics!
A lookup table in some nonvolatile memory would require fewer devices.

Post schematics instead of wiring diagrams. We are able to discern circuit intent much easier from well drawn schematics.

Colorful wiring diagrams and schematics remind me of children playing with crayons.
 

Thread Starter

maxdha

Joined Dec 3, 2023
15
A lookup table in some nonvolatile memory would require fewer devices.

Post schematics instead of wiring diagrams. We are able to discern circuit intent much easier from well drawn schematics.

Colorful wiring diagrams and schematics remind me of children playing with crayons.
Sorry about that!
Here's the schematics for the first display that shows the three letters: AFCF

I want to implement this same logic, but in a less cluttered way, and preferably without using memory!
 

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Thread Starter

maxdha

Joined Dec 3, 2023
15
You can use a set of four dual 4:1 multiplexers for each digit. Look at the dataheet for a 74HC153
SNx4HC153 Dual 4-Line To 1-Line Data Selectors/Multiplexers datasheet (Rev. E)
Each multiplexer will output 4 different values for 2 bits of the 7-segment display. Just as if it was a memory device. Easy peasy.
Thanks so much for your reply!

Would it be possible to use a counter to sequentially count from 00 to 11, and then channel this count through the multiplexers, resulting in a corresponding change on the 7-segment displays? For instance, would this setup enable the display to show 'ASU' for the count '00', 'FOE' for '01', 'CSE' for '10', and 'FUN' for '11'? (Like my messy circuit above :) )


Sorry if it's a stupid question, as I've never interacted with circuits before.
 

dl324

Joined Mar 30, 2015
16,716
Here's the schematics for the first display that shows the three letters: AFCF
We don't draw schematics that way. It makes my head spin following the wires back and forth to establish how they're connected. The preferred flow in schematics is left to right and top to bottom.

What type of switches are you using? When contacts are open, you have floating inputs and that's a no-no.

Using essentially a single current limiting resistor for all segments is a bad design practice as brightness depends on the number of segments that are turned on.
 

Thread Starter

maxdha

Joined Dec 3, 2023
15
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