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I''m a newbie Help me PLEASE - number of pins ? — Parallax Forums

I''m a newbie Help me PLEASE - number of pins ?

ArchiverArchiver Posts: 46,084
edited 2004-04-17 05:48 in General Discussion
> 1) 3 buttons - would require 3 inputs
> 2) 2 LEDs - would require 2 outputs ... a clever scheme might
use 1 output
> 3) LCD screen - depends on type could be as little as 3 outputs
could be
> several more
> 4) serial port - unidirectional communication would require 1 input
or 1 output
> - bi-directional full duplex communication would
require 1
> input and 1 output
> - bi-directional half duplex communication would
require 1
> pin used as an input or output
>
>
> So... your requirements would need to be a processor capable of
supporting
> at least 4 I/O's. While the BS1 has 8 I/O's the BS2 has 16 I/O's.
Keep
> in mind that there are several relatively easy methods for
expanding the
> number of I/O's a processor has to offer. Other things to consider
in a
> processor are speed and ease of programmability.
>
>

4 pins ?

I get 1 pin for the buttons,
1 pin for the LED's
3 pins for the LCD if it uses a serial bus
and possibly another set of pins for another serial connection.

If the LCD AND serial can be 2 wire, I can see the 4 pins easily.

but, I get 5, maybe 6 if the LCD can share the serial and each device
uses 1 pin for selection, maybe 8 if there are two seperate 3 wire
serial busses.

what am I missing ?

Dave
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