Philips Semiconductors

Product specification

80C52/80C54/80C58

CMOS single-chip 8-bit microcontrollers

1996 Aug 16

18

Reduced EMI Mode

The AO bit (AUXR.0) in the AUXR register when set disables the

ALE output.

80C52/80C54/80C58 Reduced EMI Mode

AUXR (8EH)

76

54

32

10

–

–

–

–

–

–

–

AO

AO:

Turns off ALE output.

Dual Data Pointer Register (DPTR)

The dual DPTR structure (see Figure 12) is a way by which the

80C52/54/58 will specify the address of an external data memory

location. There are two 16-bit DPTR registers that address the

external memory, and a single bit called DPS = AUXR1/bit0 that

allows the program code to switch between them.

76

54

32

10

–

–

–

–

–

–

–

DPS

Where:

DPS = AUXR1/bit0 = Switches between DPTR0 and DPTR1.

Select Reg

DPS

DPTR0

0

DPTR1

1

The DPS bit status whould be saved by software when switching

between DPTR0 and DPTR1.

DPS

DPTR1

DPTR0

DPH

(83H)

DPL

(82H)

EXTERNAL

DATA

MEMORY

SU00745A

BIT0

AUXR1

Figure 12. DPTR Structure

DPTR Instructions

The instructions that refer to DPTR refer to the data pointer that is

currently selected using the AUXR1/bit 0 register. The six

instructions that use the DPTR are as follows:

INC DPTR

Increments the data pointer by 1

MOV DPTR, #data16

Loads the DPTR with a 16-bit constant

MOV A, @ A+DPTR

Move code byte relative to DPTR to

ACC

MOVX A, @ DPTR

Move external RAM (16-bit address) to

ACC

MOVX @ DPTR , A

Move ACC to external RAM (16-bit

address)

JMP @ A + DPTR

Jump indirect relative to DPTR

The data pointer can be accessed on a byte-by-byte basis by

specifying the Low or High byte in an instruction which accesses the

SFRs. See application note AN458 for detailed operation

PARAMETER

RATING

UNIT

Operating temperature under bias

0 to +70 or –40 to +85

°C

Storage temperature range

–65 to +150

°C

0 to +13.0

V

–0.5 to +6.5

V

15

mA

Power dissipation (based on package heat transfer limitations, not device power consumption)

1.5

W

NOTES:

1. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and

functional operation of the device at these or any conditions other than those described in the AC and DC Electrical Characteristics section

of this specification is not implied.

2. This product includes circuitry specifically designed for the protection of its internal devices from the damaging effects of excessive static

charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying greater than the rated maxima.

noted.