Messages in this thread | | | Date | Mon, 28 Jul 2003 17:43:51 +0200 (MET DST) | From | "Maciej W. Rozycki" <> | Subject | Re: i8042 problem |
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On Mon, 28 Jul 2003, Andries Brouwer wrote:
> > Well, are timeouts needed at all? > > Yes. We send a command to the keyboard. It may react, or it may not.
But we need not wait for that actively. If we are unsure about a result of a command, then we may send a command in question followed with an echo request. This assures an IRQ will finally arrive and if no command response arrives before an echo response, then the keyboard ignored the command. I used this approach many years ago to differ between PS/2 keyboards (which respond with 0xfa,0xab,0x83 to a request for ID) and genuine PC/AT ones (which respond with lone 0xfa). It worked.
-- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available +
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