Manual counting with D flip flops

Earl Vickery

Joined Sep 1, 2019
10
I am trying to make a decimal counter using LEDs that can either go up and down. Currently i am playing around with a simple up counter and another counter that can go left/right. I want to have two buttons one for increase and decrease but i'm not sure how to do this while keeping the previous LEDs on and without resetting them if no data is being sent through due to the clock pulse. I'd appreciate a point in the right direction because i have been at this for the past few days trying to learn the logic behind it but i need help.

ericgibbs

Joined Jan 29, 2010
10,467
hi Earl,
Welcome to AAC.
What you are trying to build ie: a decimal Up/Down counter is quite complex.
Look at this data sheet for the LS193 Up/Down decimal counter. Page #4,,, [ ignore the parallel load inputs, Data Input A,B,C and D]
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Earl Vickery

Joined Sep 1, 2019
10
That is a lot more complicated than i thought it would be. Im just trying to simulate something like a volume control that goes up and down. Would a shift register be easier instead? that way one LED is on and that will indicate the volume level. Im only 4 weeks into learning so im not that great at understanding circuits.

I will simulate the circuit to see how it works and give it a try. Thanks for the quick reply

ericgibbs

Joined Jan 29, 2010
10,467
hi,
A shift Register would be easier, a 74LS194 is one example.
Usually the LM3915 is Log volume level indicator, which drives LED's
How are you simulating the circuit.?
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Earl Vickery

Joined Sep 1, 2019
10
I am using logism to re create it. I've given it a go but i dont think i will spend much time trying to understand it. In terms of components ive learnt about its just basic counter and registers so far.

I will look at the LM3916 pdf. Thanks again

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Earl Vickery

Joined Sep 1, 2019
10
Ok. i have played around with shift registers more. I think im close to what i want. I've removed the clock as i dont think its necessary for what i want to achieve. My question is can you simulate the L' R input and the data input as the same thing while still retaining the left/ right switch but with only two inputs? Say a decrease button and increase button that depending on which one is clicked will change the direction while also inputting the data

Thanks for the help ericgibbs you got me thinking on the right path
and those websites about debouncing looks like something i will be learning about shortly in my course

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MrChips

Joined Oct 2, 2009
21,649
It depends on whether you want to build an UP/DOWN counter or you want to learn how to design an UP/DOWN counter because the approach you take is different.

If you want to build an UP/DOWN counter, then look at a 74LS193 or 74HC193 counter chip.

If you want to design an UP/DOWN counter I believe you are not quite ready for that at your level in your digital logic course. Begin with using a series of D-type flip-flops to create an asynchronous UP counting binary counter.

Going to an UP/DOWN counter is much more complex.