12 digital clock using logisim

Thread Starter

nnpv

Joined Sep 15, 2020
4
I need to implement the hours display 12h formats and an AM/PM LED that toggles between “off” and “on” (off for AM, on for PM) when the hour reaches 12. So far i have built a clock that can go up to 0 to 19, can you help me adjust it?
step 3.JPGa.JPG
 

dl324

Joined Mar 30, 2015
11,530
I need to implement the hours display 12h formats and an AM/PM LED that toggles between “off” and “on” (off for AM, on for PM) when the hour reaches 12.
Why are you using so many flip flops?

Have you learned how to design counters without using the set or reset inputs?

1600209014104.png
What is "Stage 1"?
 

Thread Starter

nnpv

Joined Sep 15, 2020
4
Why are you using so many flip flops?
Because this require one counter for "unit" column that is display from 0 to 9 and one counter for "tens" column that is display from 0 to 1.
Have you learned how to design counters without using the set or reset inputs?
No, I have not

View attachment 217342
What is "Stage 1"?
Stage 1 is the minutes counter counts from 0 to 59. I attached below
stage 1.JPG
 

dl324

Joined Mar 30, 2015
11,530
Because this require one counter for "unit" column that is display from 0 to 9 and one counter for "tens" column that is display from 0 to 1.
If you design a counter for each digit, you don't need 4 flip flops for the hours counter.
No, I have not
So you're just slinging gates. When is this problem due? Can you post your simulation file? You'll probably need to change the extension to something supported; like .txt.
Stage 1 is the minutes counter counts from 0 to 59. I attached below
You didn't need 15 flip flops for a mod 60 counter.

EDIT: clarify that 4 in first paragraph meant flip flops.

Here's a synchronous mod 12 (01-12) counter:
1600318274619.png
You'll learn about the disadvantages of asynchronous counters and how to actually design a counter later. The binary to BCD converter I used to display the counter output is often a homework problem.
 
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Thread Starter

nnpv

Joined Sep 15, 2020
4
If you design a counter for each digit, you don't need 4 flip flops for the hours counter.
So you're just slinging gates. When is this problem due? Can you post your simulation file? You'll probably need to change the extension to something supported; like .txt.
You didn't need 15 flip flops for a mod 60 counter.

EDIT: clarify that 4 in first paragraph meant flip flops.

Here's a synchronous mod 12 (01-12) counter:
View attachment 217415
You'll learn about the disadvantages of asynchronous counters and how to actually design a counter later. The binary to BCD converter I used to display the counter output is often a homework problem.
Yeah, but I don't know why my teacher said I have to 2 different counters instead of only one mod 12 counter for that
 

dl324

Joined Mar 30, 2015
11,530
Yeah, but I don't know why my teacher said I have to 2 different counters instead of only one mod 12 counter for that
Likely because you haven't gotten far enough along yet. They start out with teaching asynchronous counters and use a more brute force design approach.

If you were designing odd sequence counters like one that counts this sequence (0,1,2,3,4,5,6,7,11,12,13,15,16,19,22,23,24,26,27,31,0,...), doing it with an asynchronous counter would be difficult because of glitches on the outputs.

If you haven't covered design with truth tables and Karnaugh maps, you couldn't design a binary to BCD converter. You can learn more about it in the datasheet attachment. The manufacturers used a ROM lookup table instead of using logic gates.
 

Attachments

dl324

Joined Mar 30, 2015
11,530
Since you're reluctant to post your .circ file, I traced your logic. Why are you using the D flip flops to store the state of the JK flip flops after they've settled? Is this something that your teacher is teaching you to do for a reason?
clipimage.jpg
Do you understand why the circuit is counting to 19 instead of 12? What are your ideas for getting the counter to count from 1-12 instead of 0-19?

Why are you decoding 10 to clear the units counter, but latching 9 to use as a clock for the tens counter? Why don't you just use the clear signal to clock the 10's counter?

When is this problem due?

If you print your circuit to a PDF file, you can post snapshots in black and white without the distracting grid:
clipimage.jpg
 
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