>-----Original Message-----
>From: Michael Rigby-Jones [mailto:Michael.Rigby-Jones@BOOKHAM.COM]
>Sent: 24 February 2004 10:01
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [PIC:] Switch debouncing
>
>
>>-----Original Message-----
>>From: llile@SALTONUSA.COM [mailto:llile@SALTONUSA.COM]
>>
>>I am a big fan of the two button up-down "slew" control for a lot of
>>interfaces:  People understand it well, it is simple to use
>and simple
>>to implement
>>
>>I have done the parabolic control two different ways. Both are pretty
>>ugly, IMHO.  One is wtoo complex, the other has a long busy
>state where
>>the processor is tied up.
>>
>>1st way was to have a periodic interrupt that polls the
>switches.  Some
>>
>>Another time I did this without interrupts by reducing the amount of
>>time I ignored a button press, no interrupts:
>
>How about something like:
>
>
>void Interrupt(void)
>{
>        if(button == PRESSED)
>                {
>                if(button_time < MAX_BUTTON_TIME)
>                        button_time++;
>                }
>        else
>                {
>                button_time = 0;
>                }
>
>        if(button_time < DEBOUNCE_TIME)
>                inc_value = 0;
>        else if(button_time < SLOW_INC_TIME)
>                inc_value = SLOW_INC_VALUE;
>        else
>                inc_value = FAST_INC_VALUE;
>
>}
>
>You then have an automagicaly increasing value in inc_value to
>be used where ever it is required in your main loop.  The
>number of increments is easily increased, and you have
>debouncing built in.

Forgot to mention the above could either be fired in a regular timer
interrupt, or possibly run from the main loop, depending on response times
etc.

Regards

Mike




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