AT89LP51RB2 datasheet(37/254 Pages) ATMEL

37 / 254 page

3722A–MICRO–10/11

AT89LP51RB2/RC2/IC2 Preliminary

Table 5-5.

Data Pointer Auto-Update

DPD1

DPD0

Update Operation for MOVX and MOVC (DPU1 = 1 & DPU0 = 1)

DPS = 0

DPS = 1

DPTR

/DPTR

DPTR

/DPTR

DPTR0++

DPTR1++

DPTR0++

DPTR0--

DPTR1++

DPTR0--

DPTR0++

DPTR1--

DPTR0++

DPTR0--

DPTR1--

DPTR0--

Table 5-6.

AUXR1

– Auxiliary Register 1

AUXR1 = A2H

Reset Value = XXX0 00X0B

Not Bit Addressable

–

ENBOOT

XSTK

GF3

–

DPS

Bit

543

Symbol

Function

ENBOOT

Set ENBOOT = 1 to map the Boot ROM in the range F800H–FFFFH. This is required to run the bootloader or access the

Flash API. When ENBOOT = 0 the Boot ROM is not accessible and normal program memory is mapped to this range.

The default value is set by the Bootloader Jump bit. See Section 24.2 on page 188.

XSTK

Extended Stack Enable. When XSTK = 0 the stack resides in IDATA and is limited to 256 bytes. Set XSTK = 1 to place

the stack in EDATA for up to 2K bytes of extended stack space. All PUSH, POP, CALL and RET instructions will incur a

one or two cycle penalty when accessing the extended stack.

GF3

This bit is a general purpose user flag.

DPS

Data Pointer Select. DPS selects the active data pointer for instructions that reference DPTR. When DPS = 0, DPTR will

target DPTR0 and /DPTR will target DPTR1. When DPS = 1, DPTR will target DPTR1 and /DPTR will target DPTR0.

Table 5-7.

DPCF

– Data Pointer Configuration Register

DPCF = A1H

Reset Value = 0000 00X0B

Not Bit Addressable

DPU1

DPU0

DPD1

DPD0

–

Bit

543

Symbol

Function

DPU1

Data Pointer 1 Update. When set, MOVX @DPTR and MOVC @DPTR instructions that use DPTR1 will also update

DPTR1 based on DPD1. If DPD1 = 0 the operation is post-increment and if DPD1 = 1 the operation is post-decrement.

When DPU1 = 0, DPTR1 is not updated.

DPU0

Data Pointer 0 Update. When set, MOVX @DPTR and MOVC @DPTR instructions that use DPTR0 will also update

DPTR0 based on DPD0. If DPD0 = 0 the operation is post-increment and if DPD0 = 1 the operation is post-decrement.

When DPU0 = 0, DPTR0 is not updated.

DPD1

Data Pointer 1 Decrement. When set, INC DPTR instructions targeted to DPTR1 will decrement DPTR1. When cleared,

INC DPTR instructions will increment DPTR1. DPD1 also determines the direction of auto-update for DPTR1 when

DPU1 = 1.

DPD0

Data Pointer 0 Decrement. When set, INC DPTR instructions targeted to DPTR0 will decrement DPTR0. When cleared,

INC DPTR instructions will increment DPTR0. DPD0 also determines the direction of auto-update for DPTR0 when

DPU0 = 1.

AT89LP51RB2 Datasheet(PDF) 37 Page - ATMEL Corporation

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