參數(shù)資料
型號: PIC16F84
廠商: Microchip Technology Inc.
英文描述: 18-pin Flash/EEPROM 8-Bit Microcontrollers
中文描述: 18引腳閃存/ EEPROM的8位微控制器
文件頁數(shù): 51/124頁
文件大?。?/td> 1060K
代理商: PIC16F84
PIC16F8X
1998 Microchip Technology Inc.
DS30430C-page 51
8.11
Watchdog Timer (WDT)
The Watchdog Timer is a free running on-chip RC
oscillator which does not require any external
components. This RC oscillator is separate from the
RC oscillator of the OSC1/CLKIN pin. That means that
the WDT will run even if the clock on the OSC1/CLKIN
and OSC2/CLKOUT pins of the device 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 Wake-up causes the device to wake-up
and continue with normal operation. The WDT can be
permanently disabled by programming configuration bit
WDTE as a ’0’ (Section 8.1).
8.11.1
WDT PERIOD
The WDT has a nominal time-out period of 18 ms, (with
no prescaler). The time-out periods vary with
temperature, V
DD
and process variations from part to
part (see DC specs). If longer time-out periods 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_REG register. Thus, time-out
periods 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 pre-
vent it from timing out and generating a device
RESET condition.
The TO bit in the STATUS register will be cleared upon
a WDT time-out.
8.11.2
WDT PROGRAMMING CONSIDERATIONS
It should also be taken into 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.
FIGURE 8-18: WATCHDOG TIMER BLOCK DIAGRAM
TABLE 8-7
SUMMARY OF REGISTERS ASSOCIATED WITH THE WATCHDOG TIMER
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
Power-on
Reset
Value on all
other resets
2007h
Config. bits
(2)
(2)
(2)
(2)
PWRTE
(1)
WDTE
FOSC1
FOSC0
(2)
81h
OPTION_
REG
x
= unknown. Shaded cells are not used by the WDT.
See Figure 8-1 and Figure 8-2 for operation of the PWRTE bit.
See Figure 8-1, Figure 8-2 and Section 8.13 for operation of the Code and Data protection bits.
RBPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
1111 1111
1111 1111
Legend:
Note 1:
2:
From TMR0 Clock Source
(Figure 6-6)
To TMR0 (Figure 6-6)
Postscaler
WDT Timer
M
U
X
PSA
8 - to -1 MUX
PSA
WDT
Time-out
1
0
0
1
WDT
Enable Bit
PS2:PS0
8
MUX
Note: PSA and PS2:PS0 are bits in the OPTION_REG register.
相關(guān)PDF資料
PDF描述
PIC16F85 18/20 Pin, 8-Bit CMOS FLASH Microcontroller with Comparators and A/D Product Brief
PIC16F86 18/20 Pin, 8-Bit CMOS FLASH Microcontroller with Comparators and A/D Product Brief
PIC16F873A 28/40-pin Enhanced FLASH Microcontrollers
PIC16F874A 28/40-pin Enhanced FLASH Microcontrollers
PIC16F876A 28/40-pin Enhanced FLASH Microcontrollers
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC16F84-04/P 功能描述:8位微控制器 -MCU 1.75KB 68 RAM 13 I/O 4MHz PDIP18 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
PIC16F84-04/P 制造商:Microchip Technology Inc 功能描述:IC 8-BIT FLASH MCU
PIC16F84-04/SO 功能描述:8位微控制器 -MCU 1.75KB 68 RAM 13 I/O 4MHz SOIC18 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
PIC16F84-04/SO 制造商:Microchip Technology Inc 功能描述:IC SM 8-BIT FLASH MCU
PIC16F84-04I/P 功能描述:8位微控制器 -MCU 1.75KB 68 RAM 13 I/O 4MHz Ind Temp PDIP18 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