83C51KB Datasheet, PDF (8/19 Pages) Intel Corporation – HIGH PERFORMANCE KEYBOARD MICROCONTROLLER

83C51KB HIGH PERFORMANCE KEYBOARD MICROCONTROLLER
Table 6. 83C51KB Signal Description
Signal
Name
A15:8^†
AD7:0^†
ALE^†
Type
O
I/O
O
Description
Address Signals . Upper address lines for the external bus. These
signals are normally used for the KSO15:8 scan function and are not
available for external memory access in a keyboard application. (See
KSO signals).
Address/Data Signals. Multiplexed lower address and data signals
for external memory. These signals are normally used for the KSO7:0
scan function and are not available for external memory access in a
keyboard application. (See KSO)
Address Latch Enable. ALE signals the start of an external bus cycle
and indicates that valid address information is available on lines A15:8
and AD7:0. Since these external address signals are normally used for
the KSO scan function, the ALE should not be used for external mem-
ory access in a keyboard application. ALE can be disabled when not
used for external memory access by setting bit 0 of SFR AUXR at
address 8EH.
Alternate
Function
KSO.15:8
P2.15:8
KSO.7:0
P0.7:0
CLK1:0
P3.3:2
I/O Clock signal. Either P3.2 or P3.3 is configurable with a 1.8KΩ pullup
INT1:0#
and with external interrupt INT0# or INT1# and used as keyboard CLK
signal.
DATA
P3.0
I/O DATA signal. P3.0 is configurable with a 1.8KΩ pullup and used as key-
board Data signal..
EA#
INT1:0#^†
I External Access. Directs program memory accesses to on-chip or off-
chip code memory. For EA# = 0, all program memory accesses are off-
chip. EA# should always be strapped to V_CC for keyboard applications
using the 83C51KB.
I External Interrupts 0 and 1. These inputs set bits IE1:0 in the TCON CLK1:0
register. If bits IT1:0 in the TCON register are set, bits IE1:0 are set by P3.3:2
a falling edge on INT1#/INT0#. If bits INT1:0 are clear, bits IE1:0 are
set by a low level on INT1:0#. For keyboard applicaitons, these signals
are normally used for the CLK signals. (See KSIINT and CDPU bits in
the PCON register)
KSI7:0
P1.7:0
I/O Keyboard Scan Inputs. Application specific keyboard signals.
KSO15:0
P2.15:8
P0.7:0
I/O Keyboard Scan Outputs. The KSO signals are application specific to
keyboard scan functions.
LED3:0
P3.7:4
I/O Light Emitting Diode Drivers. The LED signals are specifically designed to RD#, WR#,
drive LEDs connected to Vcc directly (see D.C. Characteristics). The T0
alternate functions are not available for keyboard applications.
N/C
P0.7:0^†
— No Connection Signal. This signal is to be unconnected.
I/O Port 0. This is an 8-bit quasi-bidirectional I/O port (see KSO signals,
see also AD7:0).
AD7:0
P1.7:0
I/O Port 1. This is an 8-bit quasi-bidirectional I/O port (see KSI signals).
P2.7:0
I/O Port 2. This is an 8-bit quasi-bidirectional I/O port (see also A15:8). A15:8
† _{The descriptions of RD#, WR#, ALE, P’SEN#, A15:8/P2.7:0 and AD7:0/P0.7:0 are documented for the}
standard MCS 51 microcontrollers. They are not used for these functions in keyboard applications.
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