Switch debouncer

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Anonymous
Not applicable

 I need a switch debouncer circuit built out of only PSoC ocmponents.... no firmware 

   

Can you help me

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10 Replies
Anonymous
Not applicable

 Akash,

   

You always have the option of using logic gates (Eg: a pair of nand gates) and flip-flops to create a switch-debounce circuit.

   

Regards,

   

srim

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Anonymous
Not applicable

   

There is a "Glitch filtering' component in the library.

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Anonymous
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Use an SR latch that resets itself after running an 8 bit one shot down counter clocked at say 2.5 kHz, with it reseetting itself on TC. That gives you 100 ms of delay between allowed swtich firings. An SR latch is just two NANDs or NORs with cross feedback.

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Bob_Marlowe
Level 10
Level 10
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Have a look into the datasheet of the "glitchfilter"-component and see how it works. It's using some resources, so its principle of operation can be adapted to your needs:

   

You need a clock to timeout your stages.

   

When a keypress is a logical 1 (High) you may use 2 - 3 DFFs chained together and async reset by the negated switch input. Thus the output of the last FF is normally 0 and switches to 1 after n clock cycles (where n is the number of FFs) the switch is held High.

   

 

   

Happy bouncing
Bob

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ETRO_SSN583
Level 9
Level 9
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How many switch inputs are you trying to debounce ?

   

 

   

The SR approach requires either a supporting timer or schmidt (with R-C network to

   

work properly). The glitch filter uses LUT + 3 D's. Resources required per pin.

   

 

   

One of the principal advantages of a SW solution is ease of handling many pins with

   

one main piece of HW, a timer, and some code space.

   

 

   

Regards, Dana.

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ETRO_SSN583
Level 9
Level 9
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If if absolutely has to be HW only, here is an approach -

   

 

   

http://www.eetimes.com/discussion/break-points/4024956/Solving-Switch-Bounce-Problems

   

 

   

Keep in mind a schmidt can be a comparator with hysterisis. Also possible a NI buffer with

   

fdbk R's around it, but you have to be careful about building an oscillator due to stray C.

   

 

   

Regards, Dana.

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Anonymous
Not applicable

Here is a more detail version

   

http://www.ganssle.com/debouncing.htm

   

http://www.ganssle.com/debouncing-pt2.htm

   

Enjoy 🙂

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HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

There is also a separate switch debouncer component: http://www.cypress.com/?rID=40974

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Hey, do you have a new link? That link leads to a 404 page, and I can't find that component to download

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