W78C54 데이터 시트보기 (PDF) - Winbond

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W78C54

8-BIT MICROCONTROLLER

Winbond 

W78C54

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 16 KB area.

Otherwise they will be present on the bus.

PSEN

OH

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 A2

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