# I am trying to make a Synchronous 4-bit counter using SR Flip-flop

#### RDrei9

Joined Feb 20, 2024
9
Question is:
Create a 4-bit Counter using SR Flip-Flops with the sequence 13-11-3-5-9-1-14-7-2-6 and recycles back

I tried to simulate it using Logisim by following my solution but its not working
My solution so far (not working)

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#### dl324

Joined Mar 30, 2015
16,922
Welcome to AAC!
I tried to simulate it using Logisim by following my solution but its not working
My solution so far (not working)
What isn't working correctly?

Is this schoolwork?

#### dl324

Joined Mar 30, 2015
16,922
13-11-3-5-9-1-14-7-2-6
The first 3 rows in your truth table have errors:

The next state after 0 isn't 11. After 3, it should be 5, not 11. After 2, it should be 6, not 3.

I really hate it when teachers teach you to label the flip flops backwards. A should always be the LSB (2^0).

From TI.

BCD to seven segment decoder:

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#### RDrei9

Joined Feb 20, 2024
9
Welcome to AAC!
What isn't working correctly?

Is this schoolwork?
Yes it is, i think everything is wrong hahaha. I tried to simulate this in logisim and doesnt output these inputs 13-11-3-5-9-1-14-7-2-6

#### RDrei9

Joined Feb 20, 2024
9
The first 3 rows in your truth table have errors:
View attachment 315785
The next state after 0 isn't 11. After 3, it should be 5, not 11. After 2, it should be 6, not 3.

I really hate it when teachers teach you to label the flip flops backwards. A should always be the LSB (2^0).

From TI.
View attachment 315786
BCD to seven segment decoder:
View attachment 315787
They didn't teach us about the LSB, i'll try to work on it based on your given answer. Thank you . If ever i'll ask a question again.

#### dl324

Joined Mar 30, 2015
16,922
Yes it is, i think everything is wrong hahaha. I tried to simulate this in logisim and doesnt output these inputs 13-11-3-5-9-1-14-7-2-6
That's because your truth table has a lot of errors. The counts above 9 haven't even been completed.

Don't they teach you to put your truth table is gray code order? That facilitates transferring data to Kmaps without having to think about it much.

EDIT: I waded through your truth table and you only have 1 entry correct (count of 3).

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