W78L812A24DL(2006) Просмотр технического описания (PDF) - Winbond

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W78L812A24DL
(Rev.:2006)

8-BIT MICROCONTROLLER

Winbond 

W78LE812/W78L812A

4. PIN DESCRIPTION

SYMBOL

DESCRIPTIONS

EXTERNAL ACCESS ENABLE: This pin forces the processor to execute out of external

ROM. It should be kept high to access internal ROM. The ROM address and data will not be

EA

present on the bus if EA pin is high and the program counter is within on-chip ROM area.

Otherwise they will be present on the bus.

PSEN

PROGRAM STORE ENABLE: PSEN enables the external ROM data onto the Port 0

address/data bus during fetch and MOVC operations. When internal ROM access is

performed, no PSEN strobe signal outputs from this pin. This pin also serves the alternative

function P4.6.

ALE

ADDRESS LATCH ENABLE: ALE is used to enable the address latch that separates the

address from the data on Port 0.

RST

RESET: A high on this pin for two machine cycles while the oscillator is running resets the

device.

XTAL1 CRYSTAL1: This is the crystal oscillator input. This pin may be driven by an external clock.

XTAL2 CRYSTAL2: This is the crystal oscillator output. It is the inversion of XTAL1.

VSS GROUND: Ground potential

VDD POWER SUPPLY: Supply voltage for operation.

PORT 0: Port 0 is a bi-directional I/O port which also provides a multiplexed low order

P0.0 − P0.7 address/data bus during accesses to external memory. The pins of Port 0 can be individually

configured to open-drain or standard port with internal pull-ups.

PORT 1: Port 1 is a bi-directional I/O port with internal pull-ups. The bits have alternate

functions which are described below:

P1.0 − P1.7 T2(P1.0): Timer/Counter 2 external count input

T2EX(P1.1): Timer/Counter 2 Reload/Capture control

INT2 − INT9 (P1.0 − P1.7): External interrupt 2 to 9

P2.0 − P2.7

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.

PORT 3: Port 3 is a bi-directional I/O port with internal pull-ups. The pins P3.4 to P3.7 can

be configured with high sink current which can drive LED displays directly. All bits have

alternate functions, which are described below:

RXD(P3.0): Serial Port receiver input

TXD(P3.1): Serial Port transmitter output

P3.0 − P3.7 INT0 (P3.2): External Interrupt 0

INT1(P3.3): External Interrupt 1

T0(P3.4): Timer 0 External Input

T1(P3.5): Timer 1 External Input

WR (P3.6): External Data Memory Write Strobe

RD (P3.7): External Data Memory Read Strobe

PORT 4: A 5-bit bi-directional I/O port which is bit-addressable. Pins P4.0 to P4.3 are

P4.0 − P4.6 available on 44-pin PLCC/QFP package. P4.6 is the alternative function corresponding to

PSEN .

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