W78E516B-24 Winbond, W78E516B-24 Datasheet - Page 3

• Manufacturer Part Number: W78E516B-24
• Description: 8-BIT MICROCONTROLLER
• Manufacturer: Winbond

PIN DESCRIPTION
* 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:
P0.0 P0.7
P1.0 P1.7
P2.0 P2.7
P3.0 P3.7
P4.0 P4.3
SYMBOL
XTAL1
XTAL2
PSEN
ALE
RST
V
V
EA
DD
SS
P4
MOV
MOV
SETB
CLR
TYPE
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
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.
O H PROGRAM STORE ENABLE: PSEN enables the external ROM data in the
O H ADDRESS LATCH ENABLE: ALE is used to enable the address latch that
I L
O
I
I
I
I
REG
P4, #0AH
A, P4
P4.0
P4.1
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.
Port 0 address/data bus. When internal ROM access is performed, no PSEN
strobe signal outputs originate from this pin.
separates the address from the data on Port 0. ALE runs at 1/6th of the
oscillator frequency.
RESET: A high on this pin for two machine cycles while the oscillator is
running resets the device.
CRYSTAL 1: This is the crystal oscillator input. This pin may be driven by an
external clock.
CRYSTAL 2: This is the crystal oscillator output. It is the inversion of XTAL1.
GROUND: ground potential.
POWER SUPPLY: Supply voltage for operation.
provides the upper address bits for accesses to external memory.
0D8H
; Output data "A" through P4.0 P4.3.
; Read P4 status to Accumulator.
; Set bit P4.0
; Clear bit P4.1
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DESCRIPTIONS
Publication Release Date: February 2000
W78E516B
Revision A3