Re: A86: keyboard input problem/question [reposted]
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Re: A86: keyboard input problem/question [reposted]
ok, um... when you press a key, the switch doesn't turn straight on,
like
_______/^^^^^^^^^ (imagine an electrical signal, low to high)
it does this:
______/^^\__/^\___/^^^^^^
because of lots of things that i don't entirely understand :)
this is called "bouncing"
i'm really not sure, the ti's curcuitry might automatically handle this
and you're getting something else, but i wouldn't think so
so, to debounce, you wait for it to stabalize into one state or the other
for sufficiently long before you report it. set up a loop and count
down, checking the state, if it changes before the countdown is done,
reset and ignore it. if it stays the same all that time, report the
change in key state.
i hope you will be less confused by this explanation than i am :)
-josh
On Wed, 6 Jan 1999 12:40:45 -0500 "Stephen Horne" <SHorne@Erols.com>
writes:
>
>Thanks, that's a good idea.. but what's debouncing? :-) I guess I
>could just
>check for those keys seperately too.
>
>
>
>>
>>that sounds like you need to debounce it. i'm not exactly sure how
>to
>>fix this, but try putting in a small delay after you check the key.
>i
>>think what you want is to wait for the key to be down for a certain
>>amount of time before it counts as being down and the same for when
>it's
>>released. that way, if it's down for less than that, ignore it.
>>
>>-josh
>>
>>On Tue, 5 Jan 1999 13:15:15 -0500 "Stephen Horne" <SHorne@Erols.com>
>>writes:
>>>
>>>
>>>I am trying to make an input routine which can determine the
>current
>>>status
>>>of the keyboard without pausing the keyboard. This is necessary in
>>>the
>>>program I am making -- I want there to be a blinking cursor (not
>the
>>>default
>>>system one.)
>>>
>>>The algorithm I made so far works pretty well (except for the
>>>repetition of
>>>characters -- I think I can fix that pretty easily, though,)
>however,
>>>when
>>>you press Y it will show "YZYZYZYZYYZZYZ" etc and if you press Z,
>it
>>>shows
>>>"Z Z ZZZ Z Z Z" etc. Does anyone know how to fix this?
>>>
>
>
>
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