P89LPC952FBD datasheet(41/66 Pages) PHILIPS

41 / 66 page

9397 750 14716

Preliminary data sheet

Rev. 01— 16 September 2005

41 of 66

Philips Semiconductors

P89LPC952

8-bit microcontroller with 10-bit ADC

7.25 Additional features

7.25.1 Software reset

The SRST bit in AUXR1 gives software the opportunity to reset the processor completely,

as if an external reset or watchdog reset had occurred. Care should be taken when writing

to AUXR1 to avoid accidental software resets.

7.25.2 Dual data pointers

The dual Data Pointers (DPTR) provides two different Data Pointers to specify the address

used with certain instructions. The DPS bit in the AUXR1 register selects one of the two

Data Pointers. Bit 2 of AUXR1 is permanently wired as a logic 0 so that the DPS bit may

be toggled (thereby switching Data Pointers) simply by incrementing the AUXR1 register,

without the possibility of inadvertently altering other bits in the register.

7.26 Flash program memory

7.26.1 General description

The P89LPC952 ﬂash memory provides in-circuit electrical erasure and programming.

The ﬂash can be erased, read, and written as bytes. The Sector and Page Erase functions

can erase any ﬂash sector (1 kB) or page (64 bytes). The Chip Erase operation will erase

the entire program memory. ICP using standard commercial programmers is available. In

addition, IAP and byte-erase allows code memory to be used for non-volatile data storage.

On-chip erase and write timing generation contribute to a user-friendly programming

interface. The P89LPC952 ﬂash reliably stores memory contents even after

100,000 erase and program cycles. The cell is designed to optimize the erase and

programming mechanisms. The P89LPC952 uses VDD as the supply voltage to perform

the Program/Erase algorithms.

(1) Watchdog reset can also be caused by an invalid feed sequence, or by writing to WDCON not immediately followed by a

feed sequence.

Fig 15. Watchdog timer in Watchdog mode (WDTE = 1)

PRE2

PRE1

PRE0

WDRUN

WDTOF

WDCLK

WDCON (A7H)

SHADOW REGISTER

PRESCALER

002aaa905

8-BIT DOWN

COUNTER

WDL (C1H)

watchdog

oscillator

PCLK

÷32

MOV WFEED1, #0A5H

MOV WFEED2, #05AH

reset(1)

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