參數(shù)資料
型號(hào)： P89LPC924
廠商： NXP Semiconductors N.V.
英文描述： 8-bit microcontrollers with accelerated two-clock 80C51 core 4 kB/8 kB 3 V low-power Flash with 8-bit A/D converter
中文描述： 8 -加速雙位單片機(jī)80C51的時(shí)鐘4 KB的核心/ 8 KB的3伏的低功耗Flash 8位A / D轉(zhuǎn)換器
文件頁(yè)數(shù)： 35/49頁(yè)
文件大小： 233K
代理商： P89LPC924
Philips Semiconductors
P89LPC924/925
8-bit microcontrollers with accelerated two-clock 80C51 core
Product data
Rev. 03 — 15 December 2004
35 of 49
9397 750 14471
Koninklijke Philips Electronics N.V. 2004. All rights reserved.
8.23 Watchdog timer
The watchdog timer causes a system reset when it underflows as a result of a failure
to feed the timer prior to the timer reaching its terminal count. It consists of a
programmable 12-bit prescaler, and an 8-bit down counter. The down counter is
decremented by a tap taken from the prescaler. The clock source for the prescaler is
either the PCLK or the nominal 400 kHz Watchdog oscillator. The watchdog timer can
only be reset by a power-on reset. When the watchdog feature is disabled, it can be
used as an interval timer and may generate an interrupt.
Figure 11
shows the
watchdog timer in Watchdog mode. Feeding the watchdog requires a two-byte
sequence. If PCLK is selected as the watchdog clock and the CPU is powered-down,
the watchdog is disabled. The watchdog timer has a time-out period that ranges from
a few
μ
s to a few seconds. Please refer to the P89LPC924/925User’s Manual for
more details.
8.24 Additional features
8.24.1
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.
8.24.2
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.
(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 11. Watchdog timer in Watchdog mode (WDTE = ‘1’).
PRE2
PRE1
PRE0
–
–
WDRUN
WDTOF
WDCLK
WDCON (A7H)
CONTROL REGISTER
PRESCALER
002aaa423
SHADOW
REGISTER
FOR WDCON
8-BIT DOWN
COUNTER
WDL (C1H)
Watchdog
oscillator
PCLK
÷
32
MOV WFEED1, #0A5H
MOV WFEED2, #05AH
RESET
see note (1)
相關(guān)PDF資料
PDF描述
P89LPC925 8-bit microcontrollers with accelerated two-clock 80C51 core 4 kB/8 kB 3 V low-power Flash with 8-bit A/D converter
P89LPC930 8-bit microcontrollers with two-clock 80C51 core 4 kB/8 kB 3 V Flash with 256-byte data RAM
P89LPC933 8-bit microcontroller with accelerated two-clock 80C51 core 4 kB/8 kB 3 V byte-erasable Flash with 8-bit A/D converters
P89LPC934 8-bit microcontroller with accelerated two-clock 80C51 core 4 kB/8 kB 3 V byte-erasable Flash with 8-bit A/D converters
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
P89LPC9241 制造商:PHILIPS 制造商全稱(chēng):NXP Semiconductors 功能描述:8-bit microcontroller with accelerated two-clock 80C51 core 2 kB/4 kB/8 kB 3 V byte-erasable flash with 8-bit ADC
P89LPC9241FDH 制造商:PHILIPS 制造商全稱(chēng):NXP Semiconductors 功能描述:8-bit microcontroller with accelerated two-clock 80C51 core 2 kB/4 kB/8 kB 3 V byte-erasable flash with 8-bit ADC
P89LPC9241FDH,112 功能描述:8位微控制器 -MCU MCU 8-Bit CISC 4KB Flash2.5V/3.3V 20Pin RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
P89LPC924FDH 制造商:NXP Semiconductors 功能描述:MCU 8BIT 80C51 4K FLASH TSSOP20
P89LPC924FDH,518 功能描述:8位微控制器 -MCU 4K FL/256B RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
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