AVR-Chat

Hello 2AVR-Chat members.

I have interrupt based keyboard inquiry. How much time I need wait
after interrupt occurs and keyboard inquiry?
Thanks.

--
 Valerij Avrealij

--- In AVR-Chat@yahoogroups.com, Valerij Avrealij <avrealij@m...> 
wrote:
> Hello 2AVR-Chat members.
> 
> I have interrupt based keyboard inquiry. How much time I need wait
> after interrupt occurs and keyboard inquiry?
> Thanks.
> 
> --
>  Valerij Avrealij

It depends on the bounce time of the switches. Sometimes the 
manufacture datasheet has the specs for the bounce, settling, time. 
Most don't. Probably needless to say, but I'll say it anyway in case 
there is folks that are not awhere of it. From the time that a switch 
makes initial contact and a valid read is made of what switch created 
the closure, the contact needs to settle to a continuous closure.

Anyway, for your case if you feel you are having problems with 
contact bounce or something else and feel a time-delay is need go 
ahead a insert a delay. Start with something big that WILL correct 
the problem, say a 0.001 or may be 0.01 or even 0.1 and see what 
happens. When the problem is corrected say between 0.001 and 0.01, 
split the difference and try 0.05. If that worked split the 
difference again. You will eventually get to a point where one delay 
works and just a bit faster fails. Using the number that works 
increase the delay a little, I usually use 10% slower. This gives you 
a little insurance.

Mike

Çäðàâñòâóéòå, brewski922.

Âû ïèñàëè 20 ôåâðàëÿ 2005 ã., 19:20:56:



> --- In AVR-Chat@yahoogroups.com, Valerij Avrealij <avrealij@m...> 
> wrote:
>> Hello 2AVR-Chat members.
>> 
>> I have interrupt based keyboard inquiry. How much time I need wait
>> after interrupt occurs and keyboard inquiry?
>> Thanks.
>> 
>> --
>>  Valerij Avrealij


> Anyway, for your case if you feel you are having problems with 
> contact bounce or something else and feel a time-delay is need go 
> ahead a insert a delay. Start with something big that WILL correct 
> the problem, say a 0.001 or may be 0.01 or even 0.1 and see what 
> happens. When the problem is corrected say between 0.001 and 0.01, 
> split the difference and try 0.05. If that worked split the 
> difference again. You will eventually get to a point where one delay
> works and just a bit faster fails. Using the number that works 
> increase the delay a little, I usually use 10% slower. This gives you
> a little insurance.

> Mike

You mean 0.01 sec or 0.01 mS or 0.01uS delay?
Thanks

-- 

 Valerij

<http://www.ganssle.com/debouncing.pdf>

ST


>> Anyway, for your case if you feel you are having problems with
>> contact bounce

Valerij Avrealij wrote:

> Çäðàâñòâóéòå, brewski922.
> 
> Âû ïèñàëè 20 ôåâðàëÿ 2005 ã., 19:20:56:
> 
> 
> 
> 
>>--- In AVR-Chat@yahoogroups.com, Valerij Avrealij <avrealij@m...> 
>>wrote:
>>
>>>Hello 2AVR-Chat members.
>>>
>>>I have interrupt based keyboard inquiry. How much time I need wait
>>>after interrupt occurs and keyboard inquiry?
>>>Thanks.
>>>
>>>--
>>> Valerij Avrealij
> 
> 
> 
>>Anyway, for your case if you feel you are having problems with 
>>contact bounce or something else and feel a time-delay is need go 
>>ahead a insert a delay. Start with something big that WILL correct 
>>the problem, say a 0.001 or may be 0.01 or even 0.1 and see what 
>>happens. When the problem is corrected say between 0.001 and 0.01, 
>>split the difference and try 0.05. If that worked split the 
>>difference again. You will eventually get to a point where one delay
>>works and just a bit faster fails. Using the number that works 
>>increase the delay a little, I usually use 10% slower. This gives you
>>a little insurance.
> 
> 
>>Mike
> 
> 
> You mean 0.01 sec or 0.01 mS or 0.01uS delay?
> Thanks
> 
I would say mike is talking about whole seconds, as most bounce is over 
in 100ms or less, depending on the switch (some like power switches can 
be worse than others (like PCB mount reset switchies (the ones on the 
STK500 etc))

Regards,

Kat.

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IM: Yahoo: PinkyDwaggy  MSN: katinka@kaqelectronics.dyndns.org
For Everything Electronics     Phone: 0419 923 731
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--- In AVR-Chat@yahoogroups.com, "brewski922" <brewski@i...> wrote:
> 
> --- In AVR-Chat@yahoogroups.com, Valerij Avrealij <avrealij@m...> 
> wrote:
> > Hello 2AVR-Chat members.
> > 
> > I have interrupt based keyboard inquiry. How much time I need wait
> > after interrupt occurs and keyboard inquiry?
> > Thanks.
> > 
> > --
> >  Valerij Avrealij
> 
> It depends on the bounce time of the switches. Sometimes the 
> manufacture datasheet has the specs for the bounce, settling, time. 
> Most don't. Probably needless to say, but I'll say it anyway in 
case 
> there is folks that are not awhere of it. From the time that a 
switch 
> makes initial contact and a valid read is made of what switch 
created 
> the closure, the contact needs to settle to a continuous closure.
> 
> Anyway, for your case if you feel you are having problems with 
> contact bounce or something else and feel a time-delay is need go 
> ahead a insert a delay. Start with something big that WILL correct 
> the problem, say a 0.001 or may be 0.01 or even 0.1 and see what 
> happens. When the problem is corrected say between 0.001 and 0.01, 
> split the difference and try 0.05. If that worked split the 
> difference again. You will eventually get to a point where one 
delay 
> works and just a bit faster fails. Using the number that works 
> increase the delay a little, I usually use 10% slower. This gives 
you 
> a little insurance.
> 
> Mike

0.001 sec or 1/1000 or One One-Thousands of a second
0.01 sec or 1/100 or One One-Hundreds of a second
0.1 sec or 1/10 or One One-Tenth of a second

The theory is 
"Find a value that does not work."
"Find a value that does work."
Then pick a value 1/2 way between the two. Does it work?
Keep on dividing and testing until you get to a value, say 0.123, 
that works. A value of 0.122 on occasion fails. Add 10% to it.
0.135 sec = 0.123 + 0.012 or 135/1000 or 
delay_ms(135); //This seems to be a huge amount to me!
It is better to be slow and correct than fast and wrong.
Ten per cent is old engineering guess-work.
Mike

Hi!

  I tray to use Tiny12 but I have problem with crystal
oscilator or with ponyprog(2000). I set fuses as 1101
(CKSEL3...0) but tiny still work with internal RC
oscilator. Where may be a problem?

  Thanks for any help! Have a nice day!

                           Grzesiek


		
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Thanks to all for quick help. I'll try find my optimal delay.


> 0.001 sec or 1/1000 or One One-Thousands of a second
> 0.01 sec or 1/100 or One One-Hundreds of a second
> 0.1 sec or 1/10 or One One-Tenth of a second

> The theory is 
> "Find a value that does not work."
> "Find a value that does work."
> Then pick a value 1/2 way between the two. Does it work?
> Keep on dividing and testing until you get to a value, say 0.123, 
> that works. A value of 0.122 on occasion fails. Add 10% to it.
> 0.135 sec = 0.123 + 0.012 or 135/1000 or 
> delay_ms(135); //This seems to be a huge amount to me!
> It is better to be slow and correct than fast and wrong.
> Ten per cent is old engineering guess-work.
> Mike

-- 

 Valerij Avrealij