[maemo-developers] Problem with three keys pressed

[From: klaus.k.pedersen at nokia.com]

On  Saturday, May 05, 2012, Paolo wrote:

> I thought it might be an hardware issue...

That is a phenomon called ghost-key. This is something inherent in matrix-keyboards.

http://www.dribin.org/dave/keyboard/one_html/

> Too bad, I'll try to find a workaround.

The only workaround is to suppress the 3'rd key (which will appear as two new keys) if the pressed keys form a rectangle in the keyboard matrix.
________________________________________
From: maemo-developers-bounces at maemo.org [maemo-developers-bounces at maemo.org] on behalf of ext Paolo Iommarini [sakya_tg at yahoo.it]
Sent: Saturday, May 05, 2012 9:08 PM
To: maemo-developers
Subject: Re: Problem with three keys pressed

I thought it might be an hardware issue...
Too bad, I'll try to find a workaround.

Many thanks

> On Sat, 5 May 2012, Paolo Iommarini wrote:
>
>> I have a problem when three keys are pressed (I have the english
>> keyboard).
>> There are some keys combination that generates an additional key press.
>> This seems a system bug.
>>
>> It can be reproduced in any textbox (like the contact search).
>> If you press a+x+up arrow you'll see a "p".
>>
>> I noticed it while using the Game Gripper with the psx emulator:
>> pressing down+left+circle will end in a down+left+triangle+circle
>> combination.
>> I debugged the key-press-event and it is really getting a press event
>> for the key "p" (code 33).
>>
>> There are also other strange keys combination like
>> a+x+return = ","
>> a+x+. = "o."
>>
>> Can someone please test it and say if it's really a system bug?
>
> This is a hardware issue. And there are more combinations revealing this
> issue. See for example here:
>
> http://talk.maemo.org/archive/index.php/t-40806.html
>
> I believe it is possible to recognize the fake key press/release events
> by analyzing the timing of those events, thus discarding these events
> and working around the hardware problem. But to my knowledge, noone has
> done it yet, and I do not expect anyone to actually do it.
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