What's CNI?  I'm guessing something 24F specific?

This is how I debounce on 16F and 18F... periodic interrupt reads =20
switch state and shifts into a register.  Each time a new value is =20
shifted in, I look for patterns -- for an active-low switch, 11111110 =20
means the switch was just pressed (before any bouncing occurred).  =20
00000001 means it was just released (well after all bouncing stops).

FWIW, rather than act on a switch press, I start a timer.  If the =20
switch is released before a specific time, I perform a "click" action. =20
  If the timer reaches a specific value before the switch is released, =20
then I perform a "long-click" action.  In a different app, when the =20
switch is released I start a timer and if pressed again within a =20
certain time, it's a double-click.

Cheers,
-Neil.



Quoting Andre Abelian <abelian.andre@yahoo.com>:

> Thanks Bob,
>
> things becoming complicated. it sounds like doable but also becomes =20
> complicated too.
> use CNI interrupt as a state machine then change the state as soon =20
> as hit any key=A0
> after let's say 100 scan disable timer base routine. what if while =20
> disabling they press
> another key you are going to have missing number. I do not know I =20
> have to think
> but it's a good idea
>
> thanks
>
>
> AA=A0
>
>
> ________________________________
> From: Bob Blick <bobblick@ftml.net>
> To: Microcontroller discussion list - Public. <piclist@mit.edu>
> Sent: Thursday, October 6, 2011 1:24 PM
> Subject: Re: [PIC]: keypad debounce issue
>
> On Thursday, October 06, 2011 10:57 AM, "Andre Abelian"=A0 wrote:
>
>> I am reading a keypad that is connected to other board. I am using
>> PIC24FJ256GB110
>> with CCS PICC compiler. I am using CNI interrupt "port on change" and
>> connetced to all 4 rows.
>> any time any row goes low it create interrupt but also when it goes high
>> creates interrupt too.
>> the problem I am having is that I am getting duplicated key "debounce
>> issue". Normally=A0
>
> Hi Andre,
>
> Normally I just scan the keyboard every 20 to 50 milliseconds.
>
> Two reasons why I would use interrupt-on-change:
>
> 1) I'm saving power in sleep mode and use it to wake up.
> 2) I want immediate response to a keypress (fire a weapon?)
>
> But I would only use the interrupt to trigger a recurring scan. I would
> have a recurring timer that would do the actual scans. Only one would be
> enabled at a time. After a number of scans with no keypress, I would
> enable the interrupt-on-change and disable the timer-based scanning.
>
> Cheerful regards,
>
> Bob
>
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