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Synchronous Serial Port of LPC213x - is it useful for PS/2 keyboard/mouse interface

Synchronous Serial Port of LPC213x - is it useful for PS/2 keyboard/mouse interface

2005-12-20 by Yuri Ostry

Hello,

Just a stupid question from someone who still not digged up through
all those huge pile of datasheets and other documentation... 8-)

Is it possible to use SSP peripherial of LPC213x for PS/2
keyboard/mouse interface? I now trying to figure this out, reading LPC
user manual and all information that I found about PS/2 protocol, but
maybe someone already figured out that something make them completely
incompatible?

-- 
Sincerely,
 Yuri                          mailto:yuri@...

Re: [lpc2000] Synchronous Serial Port of LPC213x - is it useful for PS/2 keyboard/mouse interface

2005-12-20 by Tom Walsh

Yuri Ostry wrote:

>Hello,
>
>Just a stupid question from someone who still not digged up through
>all those huge pile of datasheets and other documentation... 8-)
>
>Is it possible to use SSP peripherial of LPC213x for PS/2
>keyboard/mouse interface? I now trying to figure this out, reading LPC
>user manual and all information that I found about PS/2 protocol, but
>maybe someone already figured out that something make them completely
>incompatible?
>
>  
>
Keep digging into the data on the keyboard protocol.  You'll find that 
it is a synchronis protocol where the keyboard is the clock generator.  
The clock line is also used as a CTS line.  IIRC, it is an 11bit 
transfer.  It's been many years since I did anything with the keyboard, 
the signals for PS/2 keyboards are identical with AT Keyboards.  XT 
keyboards were something entirely different, they were simple uarts.  
The later keybaords are intelligent and have a handshake protocol.

There is always bit-banging of the LPC port pins...  That was the 
solution I used on the 8042 controller.


TomW


-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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