# Electrical Engineering Question: MOD 4 Ripple Counter

• ravenprp
In summary: Thanks for the help!In summary, the mod 4 ripple counter counts in the sequence 10-11-12-13-10-11-12-13-etc...

#### ravenprp

Hi, I have to design a MOD 4 ripple UP counter that counts in the sequence 10-11-12-13-10-11-12-13-etc... I believe it is right, although it would be nice if you can check. I won't be able to go to the lab until a few weeks.

You can view the schematic here: http://bingweb.binghamton.edu/~ppandey1/untitled.bmp [Broken]

And also,

I have another question:

The question pretty much says:

You have a 5 bit counter. The frequency at the output terminals is what fraction of the input clock frequency?

a: 2^0 ... my answer is 1/2 the original clock freq
b: 2^1 ... my answer is 1/4 the original clock freq
c: 2^2 ... my answer is 1/8 the original clock freq
d: 2^3 ... my answer is 1/16 the original clock freq
e: 2^4 ... my answer is 1/32 the original clock freq

I'm assuming they are using a JK flip flop, and I'm pretty sure that the frequency (Q) of each flipflop after the first is halved each time and it continues throughout. Although, they don't say it's a JK. But I'm assuming you use a JK.

Thanks.

Last edited by a moderator:
-1- Can't you just use a 2-bit counter counting 0-1-2-3 and use logic to generate the output 0xA-B-C-D? And shouldn't you have a reset line to initialize your counter?

-2- Yes, each output bit in the counter will be a divide-by-2 of its input frequency.

(For Question #1) I see what you're saying. I'm not sure how I would implement a reset to initialize my counter. That's a good point, I didn't see that.

This is my updated counter:

http://img228.imageshack.us/img228/8076/untitledbx9.png [Broken]

I added a manual preset. Look good?

Last edited by a moderator:
Sorry, what exactly is the count sequence supposed to be? Also, you meant to hook up the FF reset for bit 3 to a 1, correct?

berkeman said:
Sorry, what exactly is the count sequence supposed to be?

10, 11, 12, 13... back to 10, 11, 12, 13... etc

Also, you meant to hook up the FF reset for bit 3 to a 1, correct?

Yes, sorry that got cut out of the picture.

Sorry to make extra work for you, but it would be easier for me to check your work if you showed the state transition table. Can you please summarize what all of the inputs and outputs are supposed to do as the counter counts 0xA...0xF,0xA...0xF,... ?

Hey, I figured it out. I verified it with my professor, it's good.

## 1. How does a MOD 4 ripple counter work?

A MOD 4 ripple counter is a type of digital counter that counts in base 4. It consists of four flip-flops, each representing a binary digit (0 or 1), and a series of logic gates that control the counting sequence. The flip-flops toggle between 0 and 1 as the clock signal pulses, creating a binary counting sequence of 0, 1, 2, 3, 0, 1, 2, 3, and so on.

## 2. What is the advantage of using a ripple counter over other types of counters?

One advantage of a ripple counter is its simplicity and low cost compared to other types of counters. It also has a smaller circuit layout, making it more compact and suitable for use in integrated circuits. Additionally, its counting sequence can easily be modified by changing the logic gates, making it versatile for various applications.

## 3. What is the maximum count of a MOD 4 ripple counter?

The maximum count of a MOD 4 ripple counter is 4, as it counts in base 4. This means that the counter will reset back to 0 after reaching a count of 3 (represented as 11 in binary) and continue counting from there in a repeating sequence.

## 4. How does a ripple counter handle asynchronous inputs?

A ripple counter handles asynchronous inputs by using a master-slave flip-flop configuration. This means that one flip-flop acts as the master and the other as the slave. The master flip-flop is triggered by the clock signal, while the slave flip-flop is triggered by the output of the master. This ensures that the flip-flops are only triggered when the clock signal is stable, preventing any false counts due to asynchronous inputs.

## 5. What are some common applications of a MOD 4 ripple counter?

A MOD 4 ripple counter can be used in various applications that require a counting sequence in base 4. Some common examples include frequency dividers, digital clocks, and shift registers. It can also be used in combination with other counters to create larger counting sequences, such as a MOD 10 counter for a decimal counting sequence.

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