SST89V516RD2-33-C-PJE View Datasheet(PDF) - Silicon Storage Technology

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Description

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SST89V516RD2-33-C-PJE

FlashFlex MCU

Silicon Storage Technology 

Data Sheet

Expanded RAM Access (Indirect Addressing only):

MOVX @DPTR, A

; DPTR contains 0A0H

DPTR points to 0A0H and data in “A” is written to address

0A0H of the expanded RAM rather than external memory.

Access to external memory higher than 2FFH using the

MOVX instruction will access external memory (0300H to

FFFFH) and will perform in the same way as the standard

8051, with P0 and P2 as data/address bus, and P3.6 and

P3.7 as write and read timing signals.

When EXTRAM = 1, MOVX @Ri and MOVX @DPTR will

be similar to the standard 8051. Using MOVX @Ri pro-

vides an 8-bit address with multiplexed data on Port 0.

Other output port pins can be used to output higher order

FlashFlex MCU

SST89E516RD2 / SST89E516RD

SST89V516RD2 / SST89V516RD

address bits. This provides external paging capabilities.

Using MOVX @DPTR generates a 16-bit address. This

allows external addressing up the 64K. Port 2 provides the

high-order eight address bits (DPH), and Port 0 multiplexes

the low order eight address bits (DPL) with data. Both

MOVX @Ri and MOVX @DPTR generates the necessary

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

external memory use. Table 3-3 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 3-3: External Data Memory RD#, WR# with EXTRAM bit

MOVX @DPTR, A or MOVX A, @DPTR

AUXR

ADDR < 0300H

ADDR >= 0300H

EXTRAM = 0

EXTRAM = 1

RD# / WR# not asserted

RD# / WR# asserted

RD# / WR# asserted

RD# / WR# asserted

1. Access limited to ERAM address within 0 to 0FFH; cannot access 100H to 02FFH.

MOVX @Ri, A or MOVX A, @Ri

ADDR = Any

RD# / WR# not asserted1

RD# / WR# asserted

T3-3.0 1273

©2007 Silicon Storage Technology, Inc.

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S71273-03-000

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