P80C51HFH(1997) Просмотр технического описания (PDF) - Philips Electronics

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производитель

P80C51HFH
(Rev.:1997)

Low voltage 8-bit microcontrollers with UART

Philips Electronics 

Philips Semiconductors

Low voltage 8-bit microcontrollers with

UART

Product specification

P80CL31; P80CL51

SYMBOL

ALE

EA

P0.7 to P0.0

AD7 to AD0

VDD

n.c.

PIN

DIP40

VSO40

QFP44

DESCRIPTION

30

27 Address Latch Enable. Output pulse for latching the low byte of the

address during access to external memory. ALE is emitted at a constant

rate of 1⁄6 × fosc, and may be used for external timing or clocking purposes

(assuming MOVX instructions are not used).

31

32 to 39

29

30 to 37

External Access. When EA is held HIGH the CPU executes out of internal

program memory (unless the program counter exceeds 0FFFH). Holding

EA LOW forces the CPU to execute out of external memory regardless of

the value of the program counter.

• Port 0: 8-bit open-drain bidirectional I/O port. As an open-drain output

port it can sink 8 LS TTL loads. Port 0 pins that have logic 1s written to

them float, and in that state will function as high impedance inputs.

• Low-order addressing: Port 0 is also the multiplexed low-order address

and data bus during access to external memory. The strong internal

pull-ups are used while emitting logic 1s within the low order address.

40

38 Power supply.

−

6, 17, 28, Not connected.

39

1997 Apr 15

10

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