SST89E52RC データシートの表示（PDF） - Silicon Storage Technology

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SST89E52RC

FlashFlex MCU

Silicon Storage Technology 

FlashFlex MCU

SST89E52RC / SST89E54RC

Data Sheet

read and write signals (P3.6 - WR# and P3.7 - RD#) for

external memory use. Table 3-1 shows external data mem-

ory RD#, WR# operation with EXTRAM bit.

The stack pointer (SP) can be located anywhere within the

256 bytes of internal RAM (lower 128 bytes and upper 128

bytes). The stack pointer may not be located in any part of

the expanded RAM.

TABLE 3-1: External Data Memory RD#, WR# with EXTRAM bit

MOVX @DPTR, A or MOVX A, @DPTR

AUXR

EXTRAM = 0

EXTRAM = 1

ADDR < 0100H

RD# / WR# not asserted

RD# / WR# asserted

ADDR >= 0100H

RD# / WR# asserted

RD# / WR# asserted

1. Access limited to ERAM address within 0 to 0FFH.

MOVX @Ri, A or MOVX A, @Ri

ADDR = Any

RD# / WR# not asserted1

RD# / WR# asserted

T3-1.0 1259

FFH

Expanded

RAM

256 Bytes

FFH

(Indirect Addressing)

FFH

Upper 128 Bytes

80H

Internal RAM

80H

7FH

Lower 128 Bytes

Internal RAM

(Direct Addressing)

Special

Function

Registers

(SFRs)

(Indirect Addressing)

000H

(Indirect & Direct

00H

Addressing)

FFFFH

(Indirect Addressing) FFFFH

(Indirect Addressing)

External

Data

Memory

External

Data

Memory

FFH

000H

Expanded RAM

0100H

EXTRAM = 0

FIGURE 3-1: Internal and External Data Memory Structure

0000H

©2007 Silicon Storage Technology, Inc.

10

EXTRAM = 1

S71259-04-000

1/07

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