Words on 7-Segment Displays

Thread Starter

maxdha

Joined Dec 3, 2023
15
Hello!
I'm working on a project that uses three 7-segment displays. My aim is to show the words 'CAT', 'DOG', and 'FOX' on each display, changing the word every second. To achieve this, I'm using a 74160 4-bit decade counter and a 555 Timer IC.

The 74160 will sequence the words, and the 555 Timer IC will handle the 1-second intervals. I'm looking for a simple way to program these words, as I find working with EEPROMs quite a challenge..
 

MrChips

Joined Oct 2, 2009
30,780
You need to establish the objectives of the exercise. Quite often an exercise such as this one is assigned in the context of a synchronous counter design. If that is the case, there are methodical steps in the design. If not, you can use a look-up table concept.
 

dl324

Joined Mar 30, 2015
16,897
I'm looking for a simple way to program these words, as I find working with EEPROMs quite a challenge..
It's a fairly straightforward problem, but some letters will be awkward to display on a 7 segment display (e.g. T, D vs O, G will look weird).

Since this is schoolwork, what are your ideas?
 

Thread Starter

maxdha

Joined Dec 3, 2023
15
It's a fairly straightforward problem, but some letters will be awkward to display on a 7 segment display (e.g. T, D vs O, G will look weird).

Since this is schoolwork, what are your ideas?
The problem isn't the letters themself.

My ideas are involve using an EEPROM that stores the letter patterns, but I'm sure there's some other way to use the counter to display a few preset characters.
 

Ian0

Joined Aug 7, 2020
9,765
How are you going to do an "X" that is distinguishable from an "H"?
My first suggestion is to look at all the segments that are on in all three words, and connect them so that they are permanently on.
That reduces the problem, then you can tackle it with multiplexers as @Papabravo suggested.
 

MrChips

Joined Oct 2, 2009
30,780
The first thing you need to do is sketch out on paper how you will display the desired letters. You will observe that some letters will be difficult, T, D, O, G, X.
 

joeyd999

Joined Jun 6, 2011
5,269
The first thing you need to do is sketch out on paper how you will display the desired letters. You will observe that some letters will be difficult, T, D, O, G, X.
T and D look fine in lower case. O in lower case distinguishes it from 0, and capital G looks fine.

There is no X.

Selection_101.png
 

dl324

Joined Mar 30, 2015
16,897
My ideas are involve using an EEPROM that stores the letter patterns, but I'm sure there's some other way to use the counter to display a few preset characters.
There are other memories that could be used (EPROM, PROM, NVRAM, FLASH), you could also design combinatorial logic (which is a typical solution for schoolwork).

And X will look weird too....
 

WBahn

Joined Mar 31, 2012
30,012
Hello!
I'm working on a project that uses three 7-segment displays. My aim is to show the words 'CAT', 'DOG', and 'FOX' on each display, changing the word every second. To achieve this, I'm using a 74160 4-bit decade counter and a 555 Timer IC.

The 74160 will sequence the words, and the 555 Timer IC will handle the 1-second intervals. I'm looking for a simple way to program these words, as I find working with EEPROMs quite a challenge..
Sounds like this is a good opportunity to become more comfortable working with EEPROMs.

Seriously. The more devices you establish a reasonable comfort level with, the more valuable you will be to prospective employers. So look for opportunities to step up and challenge yourself to gain new skills.
 

dl324

Joined Mar 30, 2015
16,897
Use a 4017 decade counter
OP already stated that he's using 74160.
To achieve this, I'm using a 74160 4-bit decade counter and a 555 Timer
Using a truth table for selecting the respective segments, connect the three outputs to the corresponding segments each with a diode and a resistor. Or just resistors to the base of seven transistors each turning on a segment with a resistor for each segment.
This is homework. We give hints/guidance, but we don't tell them how to do it.
 

dl324

Joined Mar 30, 2015
16,897
From your other thread, this is your "schematic":
Epic Bruticus conv 1.jpg
That light green has terrible contrast with a white background...

This is how I'd draw it:
1701834304412.png
I substituted CMOS because I don't like the huge gates my editor uses for TTL and I haven't been inclined to make them smaller. They're not going to be able to sink much current without affecting logic levels. The intent is to be able to understand what the circuit is supposed to do.

I thought that you had inputs unconnected when switches were opened. That was only because of your you had the pull up resistors about as far away from the inputs as possible.
 
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dl324

Joined Mar 30, 2015
16,897
My ideas are involve using an EEPROM that stores the letter patterns, but I'm sure there's some other way to use the counter to display a few preset characters.
Using memory devices is the easiest way. It has been done this way for over 50 years. Even when computers were displaying characters on terminals, they offloaded the decoding work to dedicated chips.

Here's a video of a simulation using ROM's in the DigitalWorks logic simulator.
 
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