p89lpc9171fdh NXP Semiconductors, p89lpc9171fdh Datasheet - Page 58

• Manufacturer Part Number: p89lpc9171fdh
• Description: 8-bit Microcontroller With Accelerated Two-clock 80c51 Core, 2 Kb 3 V Byte-erasable Flash With 8-bit Adc
• Manufacturer: NXP Semiconductors

NXP Semiconductors
P89LPC9151_61_71_2
Product data sheet
Fig 20. Watchdog timer in Watchdog mode (WDTE = 1)
(1) Watchdog reset can also be caused by an invalid feed sequence, or by writing to WDCON not immediately followed by a feed
Watchdog
oscillator
MOV WFEED1, #0A5H
MOV WFEED2, #05AH
sequence.
PCLK
7.27.1 Software reset
7.27.2 Dual data pointers
7.28.1 General description
7.27 Additional features
7.28 Flash program memory
WDCON (A7H)
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.
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.
The P89LPC9151/9161/9171 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 (256 bytes) or page (16 bytes). The Chip
Erase operation will erase the entire program memory. ICP using standard commercial
programmers is available. In addition, IAP (IAP-Lite) 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 P89LPC9151/9161/9171 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
÷32
PRE2
PRESCALER
PRE1
Rev. 02 — 9 February 2010
CONTROL REGISTER
PRE0
–
P89LPC9151/9161/9171
–
8-BIT DOWN
WDL (C1H)
COUNTER
WDRUN
8-bit microcontroller with 8-bit ADC
WDTOF
WDCLK
002aae577
© NXP B.V. 2010. All rights reserved.
reset
SHADOW
REGISTER
FOR WDCON
(1)
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