W78E58B Winbond, W78E58B Datasheet - Page 3

• Manufacturer Part Number: W78E58B
• Description: 8 BIT MICROCONTROLLER
• Manufacturer: Winbond

4. PIN DESCRIPTION
* Note: TYPE I: input, O: output, I/O: bi-directional, H: pull-high, L: pull-low, D: open drain
P0.0
P1.0
P2.0
P3.0
P4.0
SYMBOL
XTAL1
XTAL2
PSEN
RST
ALE
V
V
EA
DD
SS
P0.7
P1.7
P2.7
P3.7
P4.3
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
O H
I L
O
I
I
I
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.
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.
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.
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.
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DESCRIPTIONS
Publication Release Date: March 18, 2002
W78E58B
Revision A3