W78LE516 Datasheet, PDF (3/31 Pages) Winbond – 8-BIT MICROCONTROLLER

Preliminary W78LE516
PIN DESCRIPTION
SYMBOL
EA
PSEN
ALE
RST
XTAL1
XTAL2
VSS
VDD
P0.0−P0.7
P1.0−P1.7
P2.0−P2.7
P3.0−P3.7
P4.0−P4.3
TYPE
DESCRIPTIONS
I EXTERNAL ACCESS ENABLE: This pin forces the processor to execute the
external ROM. The ROM address and data will not be presented on the bus if
the EA pin is high.
O H _{PROGRAM STORE ENABLE: PSEN enables the external ROM data in the}
Port 0 address/data bus. When internal ROM access is performed, no PSEN
strobe signal outputs originate from this pin.
O H ADDRESS LATCH ENABLE: ALE is used to enable the address latch that
separates the address from the data on Port 0. ALE runs at 1/6th of the
oscillator frequency.
I L RESET: A high on this pin for two machine cycles while the oscillator is
running resets the device.
I CRYSTAL 1: This is the crystal oscillator input. This pin may be driven by an
external clock.
O CRYSTAL 2: This is the crystal oscillator output. It is the inversion of XTAL1.
I GROUND: ground potential.
I POWER SUPPLY: Supply voltage for operation.
I/O D PORT 0: Function is the same as that of standard 8052.
I/O H PORT 1: Function is the same as that of standard 8052.
I/O H PORT 2: Port 2 is a bi-directional I/O port with internal pull-ups. This port also
provides the upper address bits for accesses to external memory.
I/O H PORT 3: Function is the same as that of the standard 8052.
I/O H PORT 4: A bi-directional I/O. See details below.
* Note: TYPE I: input, O: output, I/O: bi-directional, H: pull-high, L: pull-low, D: open drain
PORT4
Another bit-addressable port P4 is also available and only 4 bits (P4<3:0>) can be used. This port
address is located at 0D8H with the same function as that of port P1,
Example:
P4
REG 0D8H
MOV P4, #0AH ; Output data "A" through P4.0−P4.3.
MOV A, P4
; Read P4 status to Accumulator.
SETB P4.0
; Set bit P4.0
CLR P4.1
; Clear bit P4.1
Publication Release Date: June 2000
-3-
Revision A1