Rainbow-electronics AT89C51RC Manual de usuario descargar pdf (Pagina 6)

AT89C51RC

Dual Data Pointer Registers: To facilitate accessing both

internal and external data memory, two banks of 16-bit

Data Pointer Registers are provided: DP0 at SFR address

locations 82H-83H and DP1 at 84H-85H. Bit DPS = 0 in

SFR AUXR1 selects DP0 and DPS = 1 selects DP1. The

user should always initialize the DPS bit to the appropriate

value before accessing the respective Data Pointer

Power Off Flag: The Power Off Flag (POF) is located at bit

4 (PCON.4) in the PCON SFR. POF is set to “1” during

power up. It can be set and rest under software control and

is not affected by reset.

Table 3a. AUXR: Auxiliary Register

AUXR Address = 8EH Reset Value = XXX00X00B

Not Bit Addressable

–––WDIDLE DISRTO – EXTRAM DISALE

Bit 7 6 5 4 3 2 1 0

– Reserved for future expansion

DISALE Disable/Enable ALE

DISALE Operating Mode

0 ALE is emitted at a constant rate of 1/6 the oscillator frequency

1 ALE is active only during a MOVX or MOVC instruction

EXTRAM Internal External RAM (00H-FFH) access using MOVX @ Ri/DPTR

EXTRAM Operating Mode

0 Internal ERAM (00H-FFH) access using MOVX @ Ri/DPTR

1 External data memory access

DISTRO Disable/Enable Reset out

DISRTO

0 Reset pin is driven High after WDT times out

1 Reset pin is input only

WDIDLE Disable/Enable WDT in IDLE mode

WDIDLE

0 WDT continues to count in IDLE mode

1 WDT halts counting in IDLE mode

Table 3b. AUXR1: Auxiliary Register 1

AUXR1 Address = A2H Reset Value = XXXXXXX0B

Not Bit Addressable

––– – – – –DPS

Bit 7 6 5 4 3 2 1 0

– Reserved for future expansion

DPS Data Pointer Register Select

DPS

0 Selects DPTR Registers DP0L, DP0H

1 Selects DPTR Registers DP1L, DP1H

1 2 3 4 5 6 7 8 9 10 11 ... 24 25

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Rainbow-electronics AT89C51RC Manual de usuario Pagina 6

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