AVR-Chat

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.
>
>
>
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>
> Yahoo! Groups Links
>
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> 



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