參數資料
型號： PIC16C642
廠商： Microchip Technology Inc.
英文描述： 8-Bit EPROM Microcontrollers with Analog Comparators(每個I/O口有25mA驅動/吸收電流，可編程Vref，微控制器)
中文描述： 8位EPROM微控制器與模擬比較器（每個的I / O口有25毫安驅動/吸收電流，可編程Vref的，微控制器）
文件頁數： 69/136頁
文件大小： 837K
代理商： PIC16C642
1996 Microchip Technology Inc.
Preliminary
DS30559A-page 69
PIC16C64X & PIC16C66X
9.7
Watchdog Timer (WDT)
The Watchdog Timer (WDT) is a free running on-chip
RC oscillator which does not require any external com-
ponents. The block diagram is shown in Figure 9-17.
This RC oscillator is separate from the RC oscillator of
the OSC1/CLKIN pin. This means that the WDT will
run, even if the clock on the OSC1 and OSC2 pins has
been stopped, for example, by execution of a
SLEEP
instruction. During normal operation, a WDT time-out
generates a device RESET. If the device is in SLEEP
mode, a WDT time-out causes the device to wake-up
and continue with normal operation, this is known as a
WDT wake-up. The WDT can be permanently disabled
by clearing configuration bit WDTE (Section 9.1).
9.7.1
WDT PERIOD
The WDT has a nominal time-out period of 18 ms, (with
no prescaler). The time-out period varies with temper-
ature, V
DD
and process variations from part to part (see
DC specs). If longer time-outs are desired, a prescaler
with a division ratio of up to 1:128 can be assigned to
the WDT, under software control, by writing to the
OPTION register. Thus, time-out periods of up to 2.3
seconds can be realized.
The
CLRWDT
and
SLEEP
instructions clear the WDT and
the postscaler (if assigned to the WDT) and prevent it
from timing out and generating a device RESET.
The TO bit in the STATUS register will be cleared upon
a Watchdog Timer time-out (WDT Reset and WDT
wake-up).
9.7.2
WDT PROGRAMMING CONSIDERATIONS
It should also be taken in account that under worst case
conditions (V
DD
= Min., Temperature = Max., max.
WDT prescaler) it may take several seconds before a
WDT time-out occurs.
Note:
When the prescaler is assigned to the
WDT, always execute a
CLRWDT
instruction
before changing the prescale value, other-
wise a WDT reset may occur.
FIGURE 9-17: WATCHDOG TIMER BLOCK DIAGRAM
FIGURE 9-18: SUMMARY OF WATCHDOG TIMER REGISTERS
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
2007h
81h
Legend: Shaded cells are not used by the Watchdog Timer.
Note 1: See Figure 9-1 for details of the operation of these bits.
Config. bits
OPTION
MPEEN
RBPU
BODEN
(1)
INTEDG
CP1
T0CS
CP0
T0SE
PWRTE
(1)
PSA
WDTE
PS2
FOSC1
PS1
FOSC0
PS0
From TMR0 Clock Source
(Figure 7-6)
To TMR0 (Figure 7-6)
Postscaler
WDT Timer
WDT
Enable Bit
0
1
M
U
X
PSA
8 - to - 1 MUX
PS2:PS0
0
1
MUX
PSA
WDT
Time-out
Note: PSA and PS2:PS0 are bits in the OPTION register.
8
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相關代理商/技術參數
參數描述
PIC16C642/JW 功能描述:8位微控制器 -MCU 7KB 176 RAM 22 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 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 安裝風格:SMD/SMT
PIC16C642-04/SO 功能描述:8位微控制器 -MCU 7KB 176 RAM 22 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 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 安裝風格:SMD/SMT
PIC16C642-04/SP 功能描述:8位微控制器 -MCU 7KB 176 RAM 22 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 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 安裝風格:SMD/SMT
PIC16C642-04E/SO 功能描述:8位微控制器 -MCU 7KB 176 RAM 22 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 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 安裝風格:SMD/SMT
PIC16C642-04E/SP 功能描述:8位微控制器 -MCU 7KB 176 RAM 22 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數據總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數據 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 安裝風格:SMD/SMT
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