KU80C51SL-AH View Datasheet(PDF) - Intel
Part Name
Description
Manufacturer
KU80C51SL-AH Datasheet PDF : 23 Pages
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8XC51SL LOW VOLTAGE 8XC51SL
KEYBOARD SCAN
The interface to the keyboard scan logic includes 16
slew-rate-controlled open drain scan out lines
(KSO0 –15) and eight Schmitt trigger sense lines
(KSI0 –7) with internal pullup resistors KSI0 – 7 con-
nect directly to Port 0 of the 51SL CPU The 16 scan
out lines are controlled by the four low order bits of
Port 0 Together KSO0 – 15 and KSI0– 7 form a key-
board matrix
EXTERNAL KEYBOARD AND
MOUSE INTERFACE
Industry standard PC-AT compatible keyboards em-
ploy a two wire bidirectional TTL interface for data
transmission Several sources also supply PS 2
mouse products that employ the same type of inter-
face To facilitate system expansion the 51SL pro-
vides four signal pins that may be used to implement
this interface directly for an external keyboard and
mouse
The 51SL has four high-drive open-drain bidirec-
tional port pins that can be used for external serial
interfaces such as ISA external keyboard and PS 2-
type mouse interfaces They are P30 SIF00 P31
SIF01 P33 SIF10 and P35 SIF11 P33 SIF10 is
connected to the firmware configurable level edge
sensitive INTL interrupt pin of the 51SL CPU P30
SIF00 is connected to the edge sensitive SIF0INTL
interrupt pin of the 51SL CPU Note that on the Low
Voltage 8XC51SL these inputs are protected to 5 5V
in order to provide compatibility with as many exter-
nal keyboard and PS 2 mouse devices as possible
DESIGN CONSIDERATIONS
The low voltage characteristics of the Low Voltage
8XC51SL have indicated that additional care should
be taken in selection of the crystal used in the oscil-
lator circuit In particular series resistance of a crys-
tal seems to have the largest effect on start-up time
and steady state amplitude Consequently the lower
the series resistance the better although medium to
better quality crystals are generally more than ade-
quate
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