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Questions tagged [flipflop]

a flip-flop or latch is a circuit that has two stable states and can be used to store state information.

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How propagation delay affect the operation of parallel adders, jk and t flip flop

My question is about the affect of propagation delay on parallel adders,jk and t flip flop.
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23 views

Creating coder of MFM linear code (Miller) using logic gates

I have a problem with the implementation of my MFM encoder using logic gates (in the CEDAR program). It's not working correctly, and I don't know if this is software problem, or if I'm doing something ...
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46 views

Master-Slave D flip fop

The master slave D flip-flop, is it used to prevent glitches in the data signal? Say, when there is a transition between LOW -> HIGH or HIGH -> LOW in the data signal when clock signal is at level ?
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JK flip flop integrated circuit (7473) toggle malfunction

I built a state machine using JK flip flops, I tested it but I kept getting seemingly random results. I decided to test each jk flip flop individually. Here is the schematic for my testing: simulate ...
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27 views

Analysis of Sequential Circuits - Derive the state Equations from the Diagram

How can I derive boolean expression for this diagram? This is my answer: D0 = Cnt ⊕ Z D1 = ZCnt' + ZQ'Cnt + ZCntQ' For D1, I don't know what will be the expression if the input came from ...
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3answers
68 views

Deciding which assembly is more common positive edge detector

I know of two circuits which can act as edge detector: A clock connected as a voltage source across a RC component where resistance is composed of a diode and a resistor and this in series with ...
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44 views

Master-slave circuit with enable defect

I have this task to identify a defect with this circuit, though I cannot see it. I have a feeling it has something to do with the enable input as all the master-slave circuits I come across only ...
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64 views

Sawtooth oscillations in bidirectional bus splitter [duplicate]

I am trying to listen in on a SPI-like protocol which is transferred on one busline in both directions (no slave-select). To discriminate which data is sent by which side, I need a bus splitter that ...
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1answer
46 views

De Morgan's Theorem applied on the SR Flip Flop characteristic equation

How the second equation is resulting by applying only De Morgan's theorem on the first one? How does the second one helps you build the SR flip-flop with only NAND gates?
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1answer
20 views

How to convert asynchronous set FlipFlop Hard macro into asynchronous reset FlipFlop?

My query is, if there is a asynchronous set flop in a library but the implementation or RTL required a asynchronous reset flop, how to achieve this?
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2answers
151 views

How to reverse direction of stepper motor with flip-flop

I am trying to reverse the direction of a stepper motor. The stepper motor drives a scanner head and when it gets to the end, I want it to reverse direction. I have some photo interrupters that ...
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1answer
37 views

IC 555 as monostable multivibrator

How is the output of a monostable multivibrator affected if the trigger pin is kept at a negative voltage (0V)? The upper voltage reference comparator will change its output to logic 1, while the ...
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53 views

What's the difference between a hardware register and a shift register?

There are two different wikipedia articles but they don't articulate the difference very clearly. Is the main difference that the shift registry uses a clock?
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26 views

Output Register and pipeline implementation

In his book "Finite State Machines in Hardware: Theory and Design (with VHDL and SystemVerilog)" the author said : 'The optional output register can be used to obtain a fully pipelined implementation ...
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2answers
45 views

Howto debug ngspice error PPerror: syntax error during transient analysis

In an effort to better understand software and how my computer actually works I have been experimenting with simple electronic circuits. I am working up to having three two bit registers (A, B, C) ...
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1answer
78 views

Why are latches level triggered and flip flops edge triggered?

I know what it means to be edge or level triggered but considering the block diagram or logic diagram of inside of latches and flip flops I cannot see what inside them specifies this property of each, ...
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1answer
31 views

Altera FlipFlop stuck at GND

I'm trying to make a counter that counts: 0,1,2,3,4,5 I need this for a frequency divider of 6 So I made this table: From this I get: J0= 1 K0= 1 J1 = NOT Q0 AND Q1 K1 = Q1 J2 = Q1 AND Q2 K2 =...
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42 views

flip flops RS(with NOR gates or NAND gates)

Being a total newbie, I have been reading about logic gates. I got some doubts about flip flops RS(with NOR gates or NAND gates). The flip flops are said to keep a previous state so: Why an AND gate ...
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2answers
94 views

How would I finish out this mini project (emitting 1 whenever 101 is read)?

Design a Moore finite state machine that detects 1 0 1 in consecutive digits in the input stream of 0's and 1's received every clock cycle. The circuit should output a 1 when it detects 1 0 1 ...
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1answer
78 views

Shift register using dff verilog

I want to create a shift register using d-flip-flop as basic structural element, code: dff: ...
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1answer
43 views

What happen to a dff(flip flop) without input?

I have this question but I don't know what happen to a dff without an input is it always 0 ?? like this picture below the 2nd dff hasn't any d ??? Also, if someone can draw the answer of the question ?...
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1answer
88 views

D Flip Flop Toggle — Q into Hex Inverter into D, Unstable Output, Help

simulate this circuit – Schematic created using CircuitLab I created the above circuit. There is essentially a switch that is normally high. I press a button. Using a NTE4049T hex inverter, ...
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1answer
48 views

monostable Eccles - Jordan multivibrator, theory

I’ve a few problems and questions to the principle of monostable multivibrator’s work. Basic schematic is as below: What is the reason for D1, C1, R3 elements at input? Why I can’t just tie a ...
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1answer
120 views

How to create a state transition table for a Mealy machine

I'm trying to design the counter shown in the diagram below with the counting sequence 123456 (i.e X1=1, X2=2, ...) as a Mealy machine. However, I'm having trouble figuring out how to create the ...
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1answer
59 views

How is asynchronous reset physically implemented in a flip-flop?

In Cliff Cumming's excellent paper on asynchronous vs synchronous resets, the following paragraph about the risk of metastability appears on page 19: Attention must be paid to the release of the ...
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1answer
456 views

Why ripple counter increments on each 8th pulse

I have connected the ripple counter CD4020 to an Atmega328, which sends a 50ms (low logic level) pulse to the CD4020's input each second and monitors all of its 12 outputs. However instead of ...
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2answers
1k views

No Q bar on flip-flop

I'm currently using Quartus and I'm trying to make a 4 bit counter. I noticed that when I imported the built-in flip-flop that there is no Q bar output. It's the same issue with the JK flip-flop as ...
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1answer
50 views

Design a T flip flop and draw the asynchronous state diagram

I am supposed to design a T flip flop using logic gates (asynchronous sequential circuit) and also draw the state diagram. I don't really understand why the output doesn't change from 0 to 1 when ...
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2answers
48 views

What would an acceptable replacement be for a discontinued Motorola HCT174A?

I am trying to replace a Hex D Flip-Flop on an Amiga A4000 motherboard. The original chip has the label HCT174A XAA346 I believe the datasheet describing this ...
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3answers
1k views

I know what a Reset signal is, but a Set/Reset signal? Isn't that impossible?

A schematic by Lattice Semiconductor includes the diagrammed D flip-flop. This D flip/flop accepts, among others, a Set/Reset signal. I would have understood a Set signal. I would have understood a ...
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1answer
56 views

Question about SR latch timing

I have a question about how SR latches work: To my understanding the real-world implication is that one of the two gates will receive power first and produce an output signal, and they aren't going ...
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2answers
42 views

Difference between low signal and no signal for a SR latch?

I am struggling to understand how the SR latch works. When an input has designation 0, this means "low signal" correct? Is this completely different than "no signal"? Doesn't a logic gate need some ...
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1answer
123 views

JK Flip Flop Not Toggling in Logic.ly

This may be simply a logic.ly issue. I'm trying to simulate a JK flip-flop in logic.ly/demo using two AND gates and 2 NOR gates, but the simulation does not work when both inputs are high and the ...
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1answer
161 views

Implementing circuit with d-flipflop in verilog

I'm fairly new to Verilog and I'm currently trying to do a structural implementation of a circuit that consists of an d flipflop, it has inputs x and y, x and y are exclusive or'd and that result is ...
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1answer
48 views

Using 2 Data Flip Flops to create an up counter from 0 to 3 and repeats

I've done most of the legwork. I've got this design working using 2 set reset(SR) flip flops, but I need to make it using 2 data flips, a.k.a D flip flops. What I did: Note the numbers not in ...
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1answer
222 views

8-bit synchronous up/down counter [Logisim]

I am trying to create an 8-bit programmable up/down counter using D Flip flops. So far, this is what I have: The first 3 flip flops function correctly for both up and down, but the 4th doesn't. I ...
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1answer
70 views

Setup and Hold Time: A general method to find whether a block satisfies the constraints

How to determine whether setup and hold time constrains are satisfied in a digital block? I encountered a question on the same, and it would be really helpful to know a general way to determine the ...
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1answer
145 views

J K Flip Flop and Boolean Algebra

Y=K'J'Q+K'J+KJQ' The output Y should be that of a JK flip-flop. That is: Y=JQ'+K'Q I tried to solve the following way: 1. Y=K'J'Q+K'J+KJQ' 2. =K'(J'Q+J)+KJQ' 3. =JK'+K'Q+JKQ' 4. =J(K'+KQ')+...
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2answers
135 views

(Reasonably) accurate 1Hz clock generator

I would like your advice on components before I purchase anything. I am going to make a digital 24hr clock using probably JK flip flops/multiplexors with 7 segment displays. But it must be battery-...
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2answers
65 views

Weird circuit behavior at breadboard

I have no picture to show what my circuit is like, but I'll try to draw it and explain here as best as possible. The circuit contains a NE555 timer, working in the astable mode with a frequency of ...
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1answer
80 views

Digital Logic: What are “hamming code” and “Binary code” state machines?

I'm asked to draw the circuit for a state machine in one hot, hamming code and binary code models. I know what is one hot state machine, but i'm not sure what are the other 2. Google also didn't help. ...
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1answer
2k views

CMOS implementation of D flip-flop

I am trying to implement edge triggered flip-flop using CMOS logic. Google search provides following diagram on wikipedia: Upon simulating this using tanner, I find out that output resembles positive ...
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0answers
69 views

Make a double-tapping button (ideally without ICs or keeping ICs to a minimum) for a small “tiny cell” powered device

Conditions: small device, extremely space constrained (large caps are a no-go) Powered by a small battery (something like under 120 mah) Thus, adding a few more ICs like the 555 or "TimeBlox ...
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1answer
279 views

Identifying a component with only a partial part number

I have taken apart some circuitry that no longer works and I accidentally went a bit too far with the dremel. This means I've partially obscured the serial number of a component i'm wishing to ...
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1answer
72 views

Altera Cyclone IV clock-to-output delay

Trying to find what is the clock-to-output delay for registers inside EP4CE6E22C6. Have looked through the 3 Cyclone IV handbooks searching by delay but have not found any values specified. All the ...
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1answer
33 views

Why does the condition -(t_setup)<t_hold has to stand

I was given this inequality in logical circuits class and I can't figure out the reason behind it, and how can t_hold be negative. Is the condition relevant when t_hold is positive?
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1answer
261 views

How to make shift register logisim

How would i make a 4 bit shift register with d flip flops so that only 1 led is active at once. So for example if a button was pushed the first led would light up and the other 3 would be off. If the ...
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2answers
276 views

Asynchronous Active High SET & RESET D-FlipFlop

I have two pieces of modules as below, may I ask which one is the right verilog to represent an Asynchronous active high set/reset D-flip flop (Rising clock edge)? Are both of them logically ...
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1answer
79 views

voltage output and flip flop output

Shown below is the circuit I would like to implement. (the circuit is from this paper). Basically, it's a circuit designed to cut off voltage when electrochemical etching is done. The sudden drop in ...
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1answer
101 views

How many flip flops are required to build a digital circuit?

Here is an example: The periode of the this circuit is 9, and i want to build a digital circuit with only J-K flip flops. Here is my argument, I can tell there is nine different states that leads ...