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Questions tagged [debounce]

When a mechanical switch closes it's contacts typically do not close "cleanly" and tend to bounce or chatter. This rapidly switching signal could be misread in certain situations so it is usual to attempt to reduce this bouncing to ensure a clean switch detection. the danger is that if the switch is not de-bounced you can detect multiple events from one opening or closing. Can be accomplished using analog circuits or digital circuits.

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Question about debouncing - delay of state change

I have a very simple project where I needed to debounce a button (in software). Logically, my thought process is: If the state's been stable for a while, and it changes, then immediately signal an ...
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5answers
5k views

Why can't I see bouncing of a switch on an oscilloscope?

I'm trying to view the bouncing of a simple switch on an oscilloscope. I have prepared a simple breadboard circuit (power → switch → resistor → ground). The problem is, it is displayed as a perfect ...
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3answers
50 views

How to debounce a low pulse switch for automotive lighting

Hoping you guys can give me a hand with some wiring that I can't quite figure out! Background: I'm trying to rewire a set of automotive lights - these are normally controlled by a computer but I'm ...
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1answer
84 views

Debouncer with LED inside

How It's possible to add a LED to a line that it's debounced (switch) with an RC circuit. If I place 2 LED, one on ground and one on VCC to know button position. Will they remove my charge/discharge ...
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0answers
48 views

Driving transistors without using MCUs

I'm trying to drive transistors with just a push of a button without using a MCU. The circuit I drawn drives different transistor on every button push and resets back. First part is a debounce circuit ...
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4answers
93 views

How do you pick component values for a debouncing filter?

I bought an incremental/quadrature rotary encoder for a project I'm working on. The specs: https://www.bourns.com/docs/Product-Datasheets/PEC12R.pdf They provide a diagram of a suggested filter ...
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3answers
53 views

Really occasional malfunction of the Schmitt-trigger input

I'm using some Schmitt-trigger inputs for debouncing the interrupt problems. Referring to above circuit, the circuit has a RC circuit and the output of the RC circuit goes to the Schmitt-trigger IC(...
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2answers
72 views

Non-shorting Rotary Switch “dead” Time

Is there a nominal dead time for rotary switches? Obviously all switches are different, so this value will not be precise. For making a reasonable situation, let us assume that a detent style switch ...
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3answers
96 views

Interrupt debouncer for switch sensor

I want to read the state of a switch sensor (magnetic contact). I'm thinking to connect the switch between an interrupt pin of my micro and ground, listening for CHANGE status. In this way I have ...
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1answer
82 views

De-bounce circuit?

I have a laser sensor that randomly triggers on sunlight. The signal is fed to an opti-coupler to a FTDI chip. I am looking for advice for the easiest solution to take out these false positives ...
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0answers
35 views

Simplest schmitt trigger with fewest part count for microcontroller

I own several AT89C4051 microcontrollers and I'm currently trying to read signature bytes of the micros that I probably broke (by applying 7.2V to the VCC pin before noticing the 5V regulator became a ...
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1answer
65 views

Debouncing IC input resistor?

I've recently been working on a breadboard compatible compact debouncing PCB. I found the MAX6816, a debouncing IC - check the spreadsheet here. I made the below simple circuit as per the "Typical ...
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1answer
95 views

Is there such 555 timer circuit?

I was wondering if there is a simple 555 Timer circuit, or even simple transistors circuit, that has a HIGH output for 1sec, 2sec, or more seconds when I trigger the input switch and will remain HIGH ...
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1answer
33 views

Digital Counter signal oscillation

I've a digital counter (Kubler Codix 908) with integrated 30Hz interference input filter integrated, but sometimes (when the contact that will increment the counter is closed) it counts two pieces... ...
0
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1answer
135 views

8051 program not processing keypad matrix correctly

I made myself a small PCB (measuring about 6cm by 5cm). This is what is supposed to happen: Upon power-up, the LED goes red to indicate that the unit is ready for input. I then press any key down (...
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1answer
156 views

Induced power supply noise on switch contact

I have a circuit that has a 24V section and a 5V section, separated by opto-isolators and an isolated DCDC converter. Both sides of the DC-DC have decoupling caps, and the MCU has one per Vcc pin. ...
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1answer
106 views

Preventing long-press button function on DFPlayer board

I'm using DFPlayer in stand-alone mode (no Arduino) for a music project. The buttons all have short-press and long-press commands. I want to trigger a short-press command by releasing a depressed ...
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1answer
53 views

Do we need to debounce the switch for key release

I understand that key debounce has to be considered either in Hardware (HW) or in software (SW) when we press a switch (to avoid make and breaks). Do we need to take care of key debounce even for key ...
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3answers
264 views

Calculating R and C for schmitt trigger debouncer

I've been looking all over the internet to try to figure out the optimal values for R1, R2, and C but couldn't find info. I'm trying to ideally make a debouncer that will work with any button on the ...
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2answers
1k views

Can multiple Schmitt triggers in series fully debounce a switch?

After dealing with software debouncing for a while, I find it takes a huge toll on the system, so I thought of initially making a hardware debouncer with one Schmitt trigger (74HC14), a capacitor, ...
0
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3answers
186 views

Simplest shift register test circuit - clock

I'm looking for the simplest way to test the operation of a 74HC595 shift register without complex circuitry. Currently (on a breadboard) I have a 47K SIP resistor in a pull-up fashion connected to ...
6
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4answers
2k views

Software Debouncing to detect if switch has been pressed for T seconds

I need to detect if a switch has been pressed for longer than a set time, without using any Timer registers in my embedded code. I am using software debouncing in the following manner to detect a ...
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5answers
2k views

Hardware debouncing of key matrix with minimum passive components

I have recently bought this cheap 4x4 keypad matrix. It only has the push-buttons and nothing else therefore I want to add a proper debouncing to it. The debouncing in software is something I want to ...
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3answers
1k views

Counting number of push button press by external interrupt

It's a requirement that I should count the number of button press by external or any other interrupt. So when I use the external interrupt to increment the counter by 1, it sometimes is crease by 2 ...
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1answer
883 views

debounce filter vs glitch filter [closed]

What is the difference between debounce filter and glitch filter on a mcu? I'm trying to implement a hardware debounce filtering on a ATSAM4S4C (ATMEL SAM CORTEX-M4 - PAGE 575. http://ww1.microchip....
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1answer
80 views

Delay on 12v sort of debouncing circuit?

OK - - i have an opto sensor that runs on 12v (5-30 actually) and that is power by a battery/charge regulator/ 19v power supply and is used for counting how many times somebody goes past it on a site ...
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2answers
256 views

Pull down resistor value in debouncer circuit

I am from computer background and have made debouncer circuit (SR) using NOR gate IC HD74LS02P as a part of digital electronics project. I have used pull down resistor at all inputs of the gates used. ...
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1answer
118 views

Driving a GPIO input with a momentary switch

I'm looking for a momentary switch (like this one) that can be safely driven by the GPIO pins on a Raspberry Pi 1 Model A (hereafter RPi). This model of the RPi can sustain 3.3V and up to 16mA safely ...
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2answers
3k views

Schmitt trigger in button debouncer

While researching how to debounce a switch for digital applications, I often come around this diagram : simulate this circuit – Schematic created using CircuitLab Or other similar diagrams, ...
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1answer
135 views

Switch bounce vs LC Spike Voltage

For my EE lab, our professor wants us to show switch bounce, and then eliminate it using hardware, and software debouncing. However, I seem to be stuck on finding the switch bounce in the first ...
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1answer
139 views

How to calculate the state debounce time for an analog voltage input pin?

An analog voltage input pin (AVP) of an ECU has an input voltage range of 0 to 10V and a Filter Frequency Limit of 330Hz. The input signal voltage (ISV) coming from a sensor to the AVP has a range ...
0
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1answer
326 views

What should be the debounce time for the diagnosis of short circuit to ground?

There is an analog input voltage pin of a microcontroller whose threshold voltage is set 0.2V. If the input voltage at the pin is below 0.2V, then it is recognised as the short circuit to ground(SCG). ...
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2answers
376 views

Debouncing Circuit with Schottky Diode

I found the following circuit interfacing with a GPIO input on an MCU that has an internal pull up resistor. The GPIO is being used to detect the state of the push button. I have two questions ...
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0answers
246 views

Debouncing circuit to count the pulses of a water meter with pulse emitter

I want to design a debouncing circuit to count the pulses of a water meter with pulse emitter (it behaves like a push-button). The microcontroller is the msp430g2553. I want to eliminate the rebounds ...
3
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2answers
84 views

Wires not making proper contact/interfering

I want to register button presses via a Python program I wrote with a Raspberry Pi 3. My buttons are connected both connected to ground and GPIO pins 22 and 27. However, when the buttons are pressed, ...
0
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1answer
683 views

555 Timer in monostable mode with reset on the same momentary button

I've been researching this problem for a few days. I have a 555 timer for controlling a car heated windshield, and I'd like to have a single button controlling it, and use that same button to cancel ...
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1answer
1k views

Encoders debouncing with 7414 at 3.3V

I'm trying to make a small module that has 2 rotary encoders (both have build-in push buttons), hardware debouncing circuit and have to be compatible with both 5.0V and 3.3V microcontroller logic ...
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1answer
841 views

Buttons and encoder debouncing

I'm trying to figure out the way of debouncing encoders and tact buttons with Schmidt triggers, but I'm confused with 2 existing schematics: simulate this circuit – Schematic created using ...
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1answer
872 views

Debouncing of a push button in assembly using Timer1 interrupt - PIC16F628A [closed]

I am new at assembly programming and I need to develop a debouncing code to use on a push button, for that I am required to use timer1 interrupt. The push button will be used to increment a counter ...
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0answers
84 views

Powering off a switching regulator causes MOSFET to briefly blip on. Arduino

I have stumbled upon a weird issue in my circuit below, that only happens when the DPDT slide switch, S1, goes from an upwards position(On) to the downwards ...
0
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1answer
930 views

Manual Demonstration Circuit for 74HC595 Shift Register

I am trying to create a manual demonstration circuit for a 74HC595 shift register. Se my circuit below. The problem I am having is that I am only getting a +0.7V signal to the data, clock, and latch ...
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3answers
803 views

Counter in assembly, using interrupt to prevent multiple counts with single push?

I am completely new to assembly, and I must develop a counter using PIC16F628A, a push button, and a display. Additionally it there will be an external oscillator (555). I made some progress on this, ...
0
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1answer
158 views

Doubt about the real need for R and C on micro-controller inputs [closed]

EDIT: as @Connor Wolf noted these are debouncing capacitors, sorry for the poor language I am not an engineer, I am just an hobbyist who likes to learn and understand the reason of things. I have ...
0
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1answer
125 views

Considerations for debounced power switch with Li-ion battery source

From a battery source, I have connected multiple voltage converters (100V, -1500V etc...). I wish to turn all of this on with a single switch. First of all, will a simple RC filter with large C be ...
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5answers
2k views

Why does the voltage of the photodiode “bounce”?

I have setup a BPW-21 photodiode as shown below: The photo-diode is activated by an oscillating laser beam. I expected to get a clean +5V to 0V transition at point A when the laser beam falls on the ...
2
votes
5answers
310 views

MUX input debouncing?

I am using a CP2103 to interface with a simple 74HC4051 MUX. I want to use 3 of the I/O ports on the CP2103 to control the input pins of the MUX. The 4th I/O port is being used for something else. The ...
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1answer
405 views

RC debouncer circuit does not work

I tried two circuits below, none of them seems to be working (I used 74LS04 and 74LS00), the output doesn't change when I press the switch. I found that the voltage at point "A" doesn't drop below 0....
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4answers
760 views

A question about a debouncing circuit

I was reading a tutorial on debouncing the outputs of a rotary-encoder which are read by a micro-controller. Below is the circuit given: The writer of the tutorial claims the following: "In the ...
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1answer
252 views

What is masking-time and chattering in rotary encoders?

In the datasheet of these encoders there is always a chapter mentioning masking-time and chattering. I couldn't find any tutorial on this. What are these definitions about?
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2answers
225 views

Is debounce necessary when detecting voltage on a relay switched lamp?

I'll be using an Arduino to "read" the parking light wire on a car. I was wondering if debounce is necessary here? I want to think that the factory bulb will act as a debounce to smoothen out the ...