Re: Emulating a PC keyboard
- From: Rich Grise <richgrise@xxxxxxxxxxx>
- Date: Fri, 27 May 2005 20:08:25 GMT
On Fri, 27 May 2005 15:44:04 +0000, Iain Wilkie wrote:
> I have a micro that is emulating an AT keyboard by sending scan codes and
> simply plugs onto the keyboard port of a PC. This works fine, but if I plug
> it
> into a laptop PS2 port it does not work UNLESS I put an AT keyboard in
> parallel
> with the data and clock lines. I have scoped the lines and all looks ok and
> after investigation
> it would appear that when there is no key activity, there is activity on the
> clock and data line every
> second or so which I can only imagine is the laptop asking something from
> the keyboard and if
> it doesn't get a reply then it shuts down.
>
> Anyone any idea what this message may be.
I'd try to get a snapshot of the message with and without and AT
keycoard plugged in. When they're plugged in, you can't tell which
way the data is going, because it's just open-collector. Maybe
just use a couple of pullup resistors, with no keyboard, and see
what the laptop sending, then when you plug in the keyboard, see
if it's a sort of query/ack - you can spot this if the message is
longer than without the keyboard - and if so, then in your device,
just respond to the query with the same singal as the ack that you
saw.
Hope This Helps!
Rich
.
- References:
- Emulating a PC keyboard
- From: Iain Wilkie
- Emulating a PC keyboard
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