PS2 ports use synchronous serial signals to communicate between the
keyboard or mouse to the computer. The signals are all TTL logic level
voltages
(0 volts for logical 0 and +5 volts for logical 1).
Data transmission from the mouse to the computer is
done
as in figure 1, each clock period is usually between 70 to 150 microseconds
(10 to 25 microseconds for transitions and 30 to 50 microseconds for high
or
low state), some may feel that these are large margins both this works good
since this is a synchronous port (this also helps cut on the cost of high
precision clocks). The data line transition is made on the falling edge of
the
clock signal and is usually sampled when the clock is low. Each data packet
is
composed of 11 bits, 1 start bit (which is low), 8 data bits, 1 odd parity
bit
and 1 stop bit (high).
Dunno if thats any use ;)
DesG
Once I have the datapath up and working I could look at the
Keyboard/PS2 Mouse protocol to see if I can program a PIC to do that task.
It would depent largely on the highest data rate that I could
achieve.
For
more information: http://www.automatedhome.co.uk
Post message: ukha_d@xxxxxxx
Subscribe:
ukha_d-subscribe@xxxxxxx
Unsubscribe:
ukha_d-unsubscribe@xxxxxxx
List owner:
ukha_d-owner@xxxxxxx
Your use of Yahoo! Groups is
subject to the Yahoo! Terms of
Service.