- #1
Furion
- 3
- 0
Ive been working on a new project for my studies but can't seem to get any info on 'switch bounce'
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Discussion Overview
The discussion revolves around the concept of "switch bounce," particularly in the context of electronics and project work. Participants explore the nature of switch bounce, its implications for circuit design, and methods for mitigating its effects, including switch debouncing techniques.
Discussion Character
- Technical explanation
- Conceptual clarification
- Debate/contested
- Experimental/applied
Main Points Raised
- One participant seeks information on switch bounce for a project.
- Another participant describes switch bounce as electrical noise caused by metal contacts in a switch, lasting approximately 40ms.
- A suggestion is made to use NAND gates for cleaning up switch bounce, with a reference to a resource on the topic.
- A question is raised about the relationship between switch bouncing and switch debouncing.
- It is clarified that switch bounce occurs when a mechanical switch is closed, leading to multiple rapid transitions in the circuit until it stabilizes.
- Switch debounce is defined as the process of eliminating the effects of switch bounce, with a reference to a previous suggestion for a solution.
- A participant mentions a common practice in microprocessor work to pause for a period after receiving an input to debounce a switch, sharing a personal anecdote about a related issue.
- One participant expresses understanding of the topic after the discussion.
Areas of Agreement / Disagreement
Participants generally agree on the definitions and implications of switch bounce and switch debounce, but there is some uncertainty regarding the terminology and the best methods for addressing the issue.
Contextual Notes
Some participants provide varying levels of detail about the timing and mechanisms of switch bounce and debounce, indicating a potential dependence on specific switch types and circuit designs.
Who May Find This Useful
This discussion may be useful for electronics students, hobbyists working on projects involving switches, and individuals interested in circuit design and troubleshooting related to mechanical switches.
- #2
Antiphon
- 1,685
- 4
It's the electrical noise made by metal coming together to form a circuit. It lasts maybe 40ms depending on the switch.
Google "switch debouncing circuit" and you'll get lots of examples.
Google "switch debouncing circuit" and you'll get lots of examples.
- #3
dlgoff
Science Advisor
Gold Member
- 4,441
- 3,265
If you are interested in cleaning up switch bounce (switch debounce), you can do it with a couple of nand gates.
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/setreset.html"
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/setreset.html"
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- #4
Furion
- 3
- 0
Is switch bouncing and de bouncing the same?because I am not sure
- #5
Feldoh
- 1,336
- 3
Switch debounce and switch bounce are two different things.
Switch Bounce happens when you close a mechanical switch. When you close a switch it tends to literally bounce upon the metal contact which connects the circuit.
It's almost like dropping a basketball. The basketball will hit then ground (analogous to a closed switch) then bounce back up (analogous to a open switch) then bounce back down, then up, then down, etc... until it permanently stays on the ground (permanently closed).
Usually switches take a few microseconds to a few milliseconds to completely close. What this means in terms of digital logic is that as the switch physically bounces your logic can switch back and forth low-to-high-to-low-etc... until your switch settles down.
Switch Debounce is the process of getting rid of switch bounce. One solution to get rid of switch bounce is given above by dlgoff
Switch Bounce happens when you close a mechanical switch. When you close a switch it tends to literally bounce upon the metal contact which connects the circuit.
It's almost like dropping a basketball. The basketball will hit then ground (analogous to a closed switch) then bounce back up (analogous to a open switch) then bounce back down, then up, then down, etc... until it permanently stays on the ground (permanently closed).
Usually switches take a few microseconds to a few milliseconds to completely close. What this means in terms of digital logic is that as the switch physically bounces your logic can switch back and forth low-to-high-to-low-etc... until your switch settles down.
Switch Debounce is the process of getting rid of switch bounce. One solution to get rid of switch bounce is given above by dlgoff
- #6
MATLABdude
Science Advisor
- 1,663
- 6
If you are doing microprocessor/controller work (e.g. with an externally-triggered interrupt), it's quite common practice to pause for a period of time (~20 ms or so) upon receiving an input in order to debounce a button / switch / relay.
A friend of mine nearly tore his hair out trying to fix an interrupt service routine where he'd forgotten to do this.
A friend of mine nearly tore his hair out trying to fix an interrupt service routine where he'd forgotten to do this.
- #7
Furion
- 3
- 0
ohh I get it now make a lot sense now thanks guys