参数资料
型号: P89LPC934FDH
厂商: NXP Semiconductors N.V.
元件分类: 8位微控制器
英文描述: 8-bit microcontroller with accelerated two-clock 80C51 core 4 kB-8 kB-16 kB 3 V byte-erasable flash with 8-bit ADCs
封装: P89LPC933FDH<SOT361-1 (TSSOP28)|<<http://www.nxp.com/packages/SOT361-1.html<1<week 47, 2004,;P89LPC933HDH<SOT361-1 (TSSOP28)|<<http://www.nxp.com/packages/SOT361-1.html&l
文件页数: 43/77页
文件大小: 537K
代理商: P89LPC934FDH
P89LPC933_934_935_936
All information provided in this document is subject to legal disclaimers.
NXP B.V. 2011. All rights reserved.
Product data sheet
Rev. 8 — 12 January 2011
48 of 77
NXP Semiconductors
P89LPC933/934/935/936
8-bit microcontroller with accelerated two-clock 80C51 core
8.25 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 22 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
μs to a few seconds. Please refer to the
P89LPC933/934/935/936 User manual for more details.
8.26 Additional features
8.26.1 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.
8.26.2 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 22. 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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P89LPC934FDH-S 功能描述:8位微控制器 -MCU 80C51 8K FL 256B RAM RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
P89LPC935 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:8-bit microcontroller with accelerated two-clock 80C51 core 4 kB/8 kB 3 V byte-erasable Flash with 8-bit A/D converters
P89LPC9351 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:8-bit microcontroller with accelerated two-clock 80C51 core 8 kB 3 V byte-erasable flash with 8-bit ADC
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