AT89LP6440 datasheet(11/194 Pages) ATMEL

11 / 194 page

3706A–MICRO–9/09

AT89LP6440 - Preliminary

Figure 3-1.

Program Memory Map

3.2

Internal Data Memory

The AT89LP6440 contains 256 bytes of general SRAM data memory plus 128 bytes of I/O

memory mapped into a single 8-bit address space. Access to the internal data memory does not

require any configuration. The internal data memory has three address spaces: DATA, IDATA

and SFR; as shown in Figure 3-2. Some portions of external data memory are also implemented

internally. See “External Data Memory” below for more information.

Figure 3-2.

Internal Data Memory Map

3.2.1

DATA

The first 128 bytes of RAM are directly addressable by an 8-bit address (00H–7FH) included in

the instruction. The lowest 32 bytes of DATA memory are grouped into 4 banks of 8 registers

each. The RS0 and RS1 bits (PSW.3 and PSW.4) select which register bank is in use. Instruc-

tions using register addressing will only access the currently specified bank. The lower 128 bit

addresses are also mapped into DATA addresses 20H—2FH.

Program Memory

0000

FFFF

0000

007F

User Signature Array

0100

01FF

Atmel Signature Array

SIGEN=0

SIGEN=1

AT89LP6440

FFH

UPPER

128

80H

7FH

LOWER

128

ACCESSIBLE

BY DIRECT

ADDRESSING

FFH

80H

ACCESSIBLE

BY DIRECT

AND INDIRECT

ADDRESSING

SPECIAL

FUNCTION

REGISTERS

PORTS

STATUS AND

CONTROL BITS

REGISTERS

STACK POINTER

ACCUMULATOR

(ETC.)

TIMERS

ACCESSIBLE

BY INDIRECT

ADDRESSING

ONLY

IDATA

SFR

DATA/IDATA

AT89LP6440 Datasheet(PDF) 11 Page - ATMEL Corporation

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