AVR-Chat

hello..any one can help me please..

i have a matrix kaeyboard with 12 outs..
and the keyboard its 4*4 ,,,how to connect to a avr..

and some code..please..

thank you..

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At 05:31 PM 12/16/2004, vifra gomez wrote:


>hello..any one can help me please..
>
>i have a matrix kaeyboard with 12 outs..
>and the keyboard its 4*4 ,,,how to connect to a avr..
>
>and some code..please..

I can't really figure what you mean here..
Normally you'll have some number of rows, and a number of columns.
Rows and columns are interchangeable at design time.

On the AVR, it's easiest to set up the inputs with pullups on, and output 
lows to the keyboard. (all outputs high when idle) So, you could do it as 
four rows on four output pins, and four inputs on four column pins.  Now 
you scan a low across each output, and look for lows on the inputs.

If you see all columns high, then no keys are pressed.
If you put a low on row 1 and you get a low on column 3 then you know that 
switch is closed.

How fast you scan is up to you, as well as how you debounce the switches.
If you scan slowly, you may not even need debouncing.

You may not need the pullups. According to ace Atmel FAE if you configure as 
inputs, the internal pullup resistors "may be sufficient."
D

----- Original Message ----- 
From: "Dave VanHorn" <dvanhorn@dvanhorn.org>
To: <AVR-Chat@yahoogroups.com>; <AVR-Chat@yahoogroups.com>
Sent: Thursday, December 16, 2004 4:42 PM
Subject: Re: [AVR-Chat] matrix keyboard


>
> At 05:31 PM 12/16/2004, vifra gomez wrote:
>
>
>>hello..any one can help me please..
>>
>>i have a matrix kaeyboard with 12 outs..
>>and the keyboard its 4*4 ,,,how to connect to a avr..
>>
>>and some code..please..
>
> I can't really figure what you mean here..
> Normally you'll have some number of rows, and a number of columns.
> Rows and columns are interchangeable at design time.
>
> On the AVR, it's easiest to set up the inputs with pullups on, and output
> lows to the keyboard. (all outputs high when idle) So, you could do it as
> four rows on four output pins, and four inputs on four column pins.  Now
> you scan a low across each output, and look for lows on the inputs.
>
> If you see all columns high, then no keys are pressed.
> If you put a low on row 1 and you get a low on column 3 then you know that
> switch is closed.
>
> How fast you scan is up to you, as well as how you debounce the switches.
> If you scan slowly, you may not even need debouncing.
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
> 



-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
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Se app.note AVR243, on www.atmel.com
http://www.atmel.com/dyn/products/app_notes.asp?family_id=607

Svenn :-)

>
> hello..any one can help me please..
>
> i have a matrix kaeyboard with 12 outs..
> and the keyboard its 4*4 ,,,how to connect to a avr..
>
> and some code..please..
>
> thank you..
>
> _________________________________________________________
> Do You Yahoo!?
> La mejor conexión a internet y 25MB extra a tu correo por $100 al mes. 
> http://net.yahoo.com.mx
>
>
>
>
> Yahoo! Groups Links
>
>
>
>

-----Mensagem original-----
De: vifra gomez [mailto:fravifra@yahoo.com.mx]
Enviada em: quinta-feira, 16 de dezembro de 2004 20:32
Para: AVR-Chat@yahoogroups.com
Assunto: [AVR-Chat] matrix keyboard

hello..any one can help me please..

i have a matrix kaeyboard with 12 outs..
and the keyboard its 4*4 ,,,how to connect to a avr..

and some code..please..

thank you..

_________________________________________________________
Do You Yahoo!?
La mejor conexión a internet y 25MB extra a tu correo por $100 al mes. http://net.yahoo.com.mx

--
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.296 / Virus Database: 265.5.4 - Release Date: 15/12/2004

--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.296 / Virus Database: 265.5.4 - Release Date: 15/12/2004