Questions tagged [latch]
A latch or flip-flop is a circuit that has two stable states and can be used to store state information. However latch is normally used to describe a simple storage device while flip-flop is normally reserved for clocked devices.
404
questions
0
votes
2
answers
564
views
SR latch circuit with ESP8266
I want to keep some state during a deep sleep of an ESP8266. To do this I used the following SR latch circuit:
It works well. The only change I made is that I used 2N2222 transistors.
The only ...
- 12.7k
2
votes
3
answers
215
views
Tie an input of an AND gate to its output
Let's say we have an AND gate and we give 1 as one of its inputs and we tie the other input to the gate's output.
What will happen?
- 12.7k
0
votes
1
answer
32
views
Triggering an SR Latch with multiple reset lines
Ok, so I'm relatively new to electrical engineering having worked on the software side of life in the past. I'm trying to work a simple SR Latch where only one output is enabled at once. To do this, I'...
- 15.7k
2
votes
1
answer
40
views
Latch is stable with competing capacitors?
I inherited the attached design as part of a work project. This is a latch which is meant to hold the high-voltage side of the system in the powered on state when a momentary power button attached to ...
- 2,594
2
votes
1
answer
300
views
CD4043 latch breadboard VS PCB
I am working on a circuit that contains CD4043 R/S latch. The design on the breadboard works and everything is great, as soon as the PCB was manufactured and components were soldered, an issue with ...
CommunityBot
- 1
2
votes
3
answers
319
views
Is the invalid state of an SR latch also undefined?
I understand that if both the Set and Reset inputs of an SR latch are high, the output of both Q and Not-Q is low and this is considered an invalid state.
But in this situation is the output also ...
- 16.4k
0
votes
1
answer
77
views
Is this circuit correct and safe to bypass my latch circuit, turning on the load every time I connect it to 5V?
I have this working on/off latch circuit below that works on a 8.4V battery.
I can charge and bypass the battery when I connect the circuit to a 5V charger, while still providing supply to the load ...
- 2,594
3
votes
2
answers
141
views
First time designing an SR latch; I'm using it to control the enable pin on my eFuse IC. Just want to know if I'm overlooking anything
I just finished designing my rectifier module that has a built-in voltage monitor IC and an eFuse IC.
Its purpose is to convert the 3-phase AC output from my wind turbine and use it to power my USB ...
0
votes
1
answer
49
views
Transistors falsely latch with EMI
I have a very basic NPN - PNP latching circuit:
[Sorry for the upside down image]
The latch initially is off, and when the op_amp_Signal_and_latch turns on, the ...
- 259
0
votes
1
answer
615
views
Building a D flip-flop with two D inputs using 3 S-R latches
"Use three clocked SR latches to build a D flip-flop with two D inputs (D1 and D2 ) and two clock inputs C1 and C2 . Clock C1 takes data D1 and clock C2 takes data D2 ."
Any hints how to start?
CommunityBot
- 1
0
votes
1
answer
303
views
Glitches in clock gating cell
how exactly does glitch happen for rising-edge and falling-edge ICG ?
Why for the top version of rising-edge ICG, there is no X at the MSB of the latch output ?
Note: TE signal is asynchronous to CLK,...
CommunityBot
- 1
0
votes
3
answers
226
views
Difference between latches and flip-flops in datasheet
At university and several online searches (Difference between latch and flip-flop) I have been taught that the difference between a latch and a flip-flop is that the latch is level triggered while the ...
CommunityBot
- 1
0
votes
1
answer
447
views
Latching power circuit with short-to-ground switch
I'm trying to build a circuit around an existing switch that allows another component to override the switch state. (Our component is a computer and the feature we're trying to build is remote-...
CommunityBot
- 1
0
votes
2
answers
1k
views
Soft-latch auto-reset OFF (hold) / ON (press) button, is the schematic correct?
I'm looking to make a soft-latching interface with a single momentary push button.
Required features for my build are (edited, sorry for bad description) :
Circuit should always start in OFF ...
CommunityBot
- 1
2
votes
1
answer
469
views
How to make this T-flip-flop circuit
I am trying to make a T-flip-flop circuit with a relay, which would:
toggle on a button press (12 V) [default state: off]
allow control from an external micro-controller (optocouplers)
allow ...
CommunityBot
- 1
-1
votes
3
answers
891
views
What's the best way to debounce a slider switch?
I'm really struggling with a VHDL implementation of a debouncing circuit for 2-position slider switches.I had initially planned to use an SR latch to do this but couldn't figure out how to make it ...
CommunityBot
- 1
0
votes
2
answers
141
views
ESP32 power latch circuit react on low and high (reed switch)
I am currently building a door sensor with an ESP32 and a reed switch.
My code is working with the deep sleep functionalities of the ESP32. With its help I can detect a falling/rising edge and wake ...
- 8,685
2
votes
3
answers
261
views
Push button latch circuit - switch issue
I have built a single push on/off latching circuit as per the diagram. It runs from 12 V.
It works, but the issues I have is that first, it is already on when I connect power, it should start off, ...
3
votes
0
answers
60
views
D-type LATCH output when minimum clock/enable pulse width is violated and input/output are the same [closed]
Can the output of a D-type latch go metastable when:
There is a minimum CLK/ENable pulse width violation
The input and the output of the latch have the same value?
- 21.7k
1
vote
1
answer
104
views
How to make a D-type latch not start in SET condition by itself?
I have this schematic to digitally start and stop a power supply of a Raspberry Pi, and I want to be assured that the latch doesn't start by itself in the ON state when I apply power.
Of course, if it'...
- 21.7k
1
vote
1
answer
662
views
Hold-on-hold-off soft latch power switch circuit
I'm trying to make a "hold-on-hold-off" type soft latch switch circuit, but I'm having a little trouble. I've found tons of "press-on-hold-off" types, but I haven't been able to ...
CommunityBot
- 1
10
votes
5
answers
52k
views
What is the difference between registers, flip flops and latches?
I want the answer to the very basic level. I know what they mean individually, but what I am looking for is connection between them.
- 20.9k
0
votes
1
answer
84
views
Question about T flip-flop
I am trying to implement a switch that works like the description in the picture. In my research I came across the T flip-flop, however a T flip-flop requires a clock signal. I don't have that.
Is ...
- 12.3k
0
votes
0
answers
63
views
How do I model switches in Matlab/Simulink?
I am trying to model different types of switches in Matlab/Simulink. There is this type of switch that I can't find a name for or design. I am not an expert in digital logic, I only have the basics ...
- 30.6k
-1
votes
2
answers
177
views
Is it possible to combat SR Latch oscillation or there are better alternatives?
I need to store a bit value and then ignore any attempts to store/change it again until it's reset by another signal. So I figured the SR Latch is suited for the task. However in my project there is a ...
- 10.4k
0
votes
1
answer
114
views
Why doesn't t-latch go to infinite state switching?
I've tried to build a T-Latch with NOR and AND gates in an emulator, but it causes an infinite loop.
Initial state, waiting for clock
Simulating clock impulse (the second switch)
After that it goes ...
- 16.4k
1
vote
1
answer
76
views
555 timer diagrams Q/Q bar confusion
I've seen this in several places and am perplexed. First, I thought that the output of an SR latch was Q, and the inverted output, or 'not Q' is shown as either Q with a bar over it or denoted with a ...
- 17k
2
votes
2
answers
2k
views
Earle latch properties
I just read a textbook describing the Earle latch, but no truth table was given for this device. Does anyone know this truth table?
Also, the book states that by varying the complementary clocking ...
- 8,685
0
votes
5
answers
176
views
How does electricity flow in this SR latch from Petzold’s Code?
I am confused as to how this circuit is complete and hence how electricity flows through it.
Petzold explains earlier in the book that the V refers to a battery connected to ground the way in which I ...
- 48.7k
1
vote
1
answer
206
views
How do I detect a button press between MCU loop function calls?
Currently, I have a few buttons connected via an I2C shift register, hooked up to an MCU. Super simple, so not sure if it needs a schematic, but I can share one (and any other details) if needed. I'm ...
- 2,023
1
vote
1
answer
43
views
SR latch effect which only requires one GPIO
I have an STM6821TWY6F watchdog IC for my MCU. When the MCU gracefully goes to sleep it will disable the a watchdog to prevent unwanted wake ups. The watchdog was designed to look for an oscillating ...
- 10.6k
3
votes
2
answers
142
views
How to let microcontroller power itself?
I'm trying to create a circuit where a button press results in a microcontroller booting up and sending a wifi request. I'm relatively new to electronics, so likely have a big knowledge gap.
Similar ...
- 4,621
1
vote
2
answers
452
views
Why isn't my SR latch working?
I built this SR latch out of two NOR gates. However, it doesn't seem to be working for some reason. Why not?
(Created with TinkerCAD)
Here's a circuit diagram (source is 5 V):
0
votes
0
answers
36
views
How does a D-latch work in this condition?
I think that in a D-latch the Q+ (the next state) and Q'+ (the next state and prime) must be different.
But when the {Enable D Q} = {1 0 1}, the result is ...
- 8,685
-2
votes
1
answer
84
views
How do I create a digital timing diagram based on D flip-flop signals?
We are constructing a D flip-flop using 2 latches and a control-signal coming from a clock.
The flip flop looks like this (x1 and x2 are connected to two switches, L1 and L2 are standard latches ...
0
votes
5
answers
10k
views
Comparator latch circuit
I need a VERY simple latching circuit using a comparator that will simply be off until a signal hits it (can be either + or -, I have no preference). The circuit should remain on until I reset it.
- 8,685
1
vote
2
answers
104
views
How to turn ON/OFF NE555 using a pushbutton switch that is already to ground?
I'm building a circuit for my motorcycle to replace a damaged indicator module.
It runs off a NE555 to turn on another NE555 in astable mode to flash the bulbs.
The switches on the bike are push ...
- 14.1k
6
votes
1
answer
5k
views
Resettable mechanical switch?
I'm looking for a mechanical on/off rocker or toggle switch that can be reset to a default state and position upon the removal of power.
The application is in a vehicle where I want the switch to ...
- 1
-1
votes
2
answers
68
views
Bistable memory cell with paired buffers instead of paired inverters
Bistable memory cells with paired inverters are very standard and basic building blocks (was used in Intel 8086 for example. ) But why not use paired buffers instead?
- 31.1k
4
votes
2
answers
373
views
VHDL -- K-map reduced characteristic equation fails
I have this circuit (D-latch):
and I can directly write the logical equation by only watching the gates:
$$
Q = \overline{(\overline{(D \cdot C) + Q}) + (C \cdot \overline{D})}
$$
If I want to ...
- 10.8k
0
votes
0
answers
76
views
How can SR-Latches store data over time?
My understanding is that the storing part of SR-latches boils down to having a wire loop. Ostensibly, the idea is that if there was current in the loop a second ago, there will still be current in the ...
- 4,831
0
votes
1
answer
58
views
WS2813 LED data permanently latching on power-on
I'm running into a problem where WS2813 LEDs 'latch' data permanently on start-up sometimes. The issue is sporadic, and random data is latched (RGB segments are enabled at random brightness levels on ...
- 3,538
1
vote
1
answer
356
views
In SystemVerilog, will assign a variable to itself within an always_comb block generate a latch?
In SystemVerilog, always_comb blocks must always specify the value of all the signals within them for all possible case branches ...
- 10.8k
1
vote
2
answers
115
views
Can I digitally open a circuit?
As a basis for a low power project, I want to render the useless machine not useless
https://www.youtube.com/watch?v=Z86V_ICUCD4
A useless machine is a simple mechanism that powers up when a switch is ...
- 4,978
0
votes
0
answers
40
views
Weird waveform of a digital latch
I am simulating on ADS.
As you can see, the V1 goes high at 9n sec.The clk has first rising edge at 10n sec.
Why does output V2 not go up at the 10n seconds? It goes up at 20n seconds at the second ...
- 66.8k
2
votes
2
answers
235
views
Soft Latch ON-OFF with support of DC High Voltage side, compatibile with Arduino or any Low Voltage MCU (with schematic)
First Schematic
I'm trying to implement this schematic that I found in this interesting article (Soft Latching Power Circuits). This is a circuit can substitute a mechanical on off switch, and use ...
0
votes
0
answers
87
views
24V input shutdown-latch - is it a good idea?
I want to protect my circuit by adding the ability to the MCU, to turn-off the power supply (and by this also turn itself off), in case of certain failure conditions are met. One of it would be ...
- 1,772
0
votes
2
answers
1k
views
Converting latching switch to momentary output
I'm trying to get a latch switch to send a pulse for around 3 seconds or so. The pulse doesn't need to be pretty or precise. The circuit will be used to sound a buzzer when the switch is flipped on. ...
- 1
1
vote
2
answers
93
views
What kind of latch would be best to continuously store and feed in a series of inputs?
So I've got an assignment where I've two buttons and LED screen. One button inputs a '1' and the other a '0', and when four inputs are detected the screen displays the number eg. If I typed 0011 it ...
1
vote
1
answer
176
views
Aircraft Starting Mockup Display With Buzzer Question
I am stuck in the middle of building a circuit for an aircraft starting mockup that will train our students to correctly start the aircraft without accidentally re-engaging the starter and thus ...
CommunityBot
- 1