AT80C32X2 Просмотр технического описания (PDF) - Atmel Corporation

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AT80C32X2

8-bit Microcontroller 8 Kbytes ROM/OTP, ROMless

Atmel Corporation 

Dual Data Pointer

Register (Ddptr)

Figure 3. Use of Dual Pointer

The additional data pointer can be used to speed up code execution and reduce code

size in a number of ways.

The dual DPTR structure is a way by which the chip will specify the address of an exter-

nal data memory location. There are two 16-bit DPTR registers that address the external

memory, and a single bit called

DPS = AUXR1/bit0 (See Table 5.) that allows the program code to switch between them

(Refer to Figure 3).

External Data Memory

7

0

DPS

AUXR1(A2H)

DPTR1

DPTR0

DPH(83H) DPL(82H)

Table 4. AUXR1: Auxiliary Register 1

7

6

5

4

3

2

1

-

-

-

-

GF3

0

-

Bit

Number

Bit

Mnemonic Description

7

-

Reserved

The value read from this bit is indeterminate. Do not set this bit.

6

-

Reserved

The value read from this bit is indeterminate. Do not set this bit.

5

-

Reserved

The value read from this bit is indeterminate. Do not set this bit.

4

-

Reserved

The value read from this bit is indeterminate. Do not set this bit.

3

GF3 This bit is a general purpose user flag

2

0

Reserved

Always stuck at 0

1

-

Reserved

The value read from this bit is indeterminate. Do not set this bit.

Data Pointer Selection

0

DPS Clear to select DPTR0.

Set to select DPTR1.

Reset Value = XXXX XXX0

Not bit addressable

0

DPS

10 TS8xCx2X2

4184I–8051–02/08

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