P80C557E4 查看數據表（PDF） - Philips Electronics

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P80C557E4

Single-chip 8-bit microcontroller

Philips Electronics 

Philips Semiconductors

Single-chip 8-bit microcontroller

Product specification

P83C557E4/P80C557E4/P89C557E4

6.2.1 Program Memory

The program memory of the P8xC557E4 consists of 32 Kbytes

ROM respectively FEEPROM (”Flash Memory”) on-chip, externally

expandable up to 64 Kbytes. If, during RESET, the EA pin was held

HIGH, the P8xC557E4 executes out of the internal program memory

unless the address exceeds 7FFFH. Locations 8000H through

0FFFFH are then fetched from the external program memory. If the

EA pin was held LOW during RESET the P8xC557E4 fetches all

instructions from the external program memory. The EA input is

latched during RESET and is don’t care after RESET.

The internal program memory content is protected, by setting a

mask programmable security bit (ROM) or by the software

programmable security byte (FEEPROM) respectively, i.e. it cannot

be read out at any time by any test mode or by any instruction in the

external program memory space. The MOVC instructions are the

only ones which have access to program code in the internal or

external program memory. The EA input is latched during RESET

and is ’don’t care’ after RESET. This implementation prevents from

reading internal program code by switching from external program

memory to internal program memory during MOVC instruction or an

instruction that handles immediate data. Table 1 lists the access to

the internal and external program memory with MOVC instructions

when the security feature has been activated.

6.2.2 Internal Data Memory

The internal data memory is divided into three physically separated

parts:

256 bytes of RAM, 768 bytes of AUX-RAM, and a 128 bytes special

function area. These can be addressed each in a different way (see

also Table 2).

– RAM 0 to 127 can be addressed directly and indirectly as in the

80C51. Address pointers are R0 and R1 of the selected

registerbank.

– RAM 128 to 255 can only be addressed indirectly.

Address pointers are R0 and R1 of the selected registerbank.

– AUX-RAM 0 to 767 is also indirectly addressable as external

DATA MEMORY locations 0 to 767 via MOVX-Datapointer

instruction, unless it is disabled by setting ARD = 1.

AUX-RAM 0 to 767 is indirectly addressable via pageregister

(XRAMP) and MOVX-Ri instructions, unless it is disabled by

setting ARD = 1 (see Figure 5).

When executing from internal program memory, an access to

AUX-RAM 0 to 767 will not affect the ports P0, P2, P3.6 and P3.7.

An access to external DATA MEMORY locations higher than 767

will be performed with the MOVX @ DPTR instructions in the

same way as in the 80C51 structure, so with P0 and P2 as

data/address bus and P3.6 and P3.7 as write and read timing

signals. Note that the external DATA MEMORY cannot be

accessed with R0 and R1 as address pointer if the AUX-RAM is

enabled (ARD = 0, default).

– The Special Function Registers (SFR) can only be addressed

directly in the address range from 128 to 255 (see Table 5).

– Four register banks, each 8 registers wide, occupy locations 0

through 31 in the lower RAM area. Only one of these banks may

be enabled at a time. The next 16 bytes, locations 32 through 47,

contain 128 directly addressable bit locations.The stack can be

located anywhere in the internal 256 bytes RAM.The stack depth

is only limited by the available internal RAM space of 256 bytes

(see Figure 7).

All registers except the program counter and the four register

banks reside in the Special Function Register address space.

Table 1. Memory Access by the MOVC Instruction for Protected ROMs

MOVC LOCATION

ACCESS TO INTERNAL

PROGRAM MEMORY

ACCESS TO EXTERNAL

PROGRAM MEMORY

MOVC in internal program memory

YES

YES

MOVC in external program memory

NO

YES

NOTE:

1. If the security feature has not been activated, there are no restrictions for MOVC instructions.

Table 2. Internal Data Memory Map

LOCATION

RAM

0 to 127

AUX-RAM

0 to 767

RAM

128 to 255

SFR

128 to 255

ADDRESSED

Direct and indirect

Indirect only with MOVX

Indirect only

Direct only

1999 Mar 02

9

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