W78C58 Datasheet, PDF (3/22 Pages) Winbond – 8-BIT MICROCONTROLLER

W78C58
PIN DESCRIPTION
SYMBOL TYPE
DESCRIPTIONS
EA
I EXTERNAL ACCESS ENABLE: This pin forces the processor to execute out
of external ROM. The ROM address and data will not be present on the bus if
the EA pin is high and the program counter is within the 32 KB area.
Otherwise they will be present on the bus.
PSEN
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.
ALE
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. An ALE pulse is omitted during external data memory
accesses.
RST
I L RESET: A high on this pin for two machine cycles while the oscillator is
running resets the device.
XTAL1
I CRYSTAL 1: This is the crystal oscillator input. This pin may be driven by an
external clock.
XTAL2
O CRYSTAL 2: This is the crystal oscillator output. It is the inversion of XTAL1.
VSS
VDD
P0.0−P0.7
P1.0−P1.7
P2.0−P2.7
P3.0−P3.7
P4.0−P4.3
I GROUND: Ground potential.
I POWER SUPPLY: Supply voltage for operation.
I/O D PORT 0: Function is the same as that of the standard 8052.
I/O H PORT 1: Function is the same as that of the standard 8052.
I/O H PORT 2: Function is the same as that of the standard 8052.
I/O H PORT 3: Function is the same as that of the standard 8052.
I/O H PORT 4: A 4-bit bi-directional parallel port and bit-addressable with internal
pull-ups. Pin P4.3 and P4.2 have alternative function as external interrupt
(INT2/INT3) source input.
INT2 (P4.3) I H External interrupt 2: An extra interrupt input source. It cascades to pin P4.3
internally.
INT3 (P4.2) I H External interrupt 3: An extra interrupt input source. It cascades to pin P4.2
internally.
* Note : TYPE I: input, O: output, I/O: bi-directional, H: pull-high, L: pull-low, D: open drain
Publication Release Date: December 1997
-3-
Revision A5