参数资料
| 型号： | PIC16F54-I/SS |
| 厂商： | Microchip Technology |
| 文件页数： | 35/88页 |
| 文件大小： | 0K |
| 描述： | IC MCU FLASH 512X12 20SSOP |
| 产品培训模块： | Asynchronous Stimulus 8-bit PIC® Microcontroller Portfolio |
| 标准包装： | 67 |
| 系列： | PIC® 16F |
| 核心处理器： | PIC |
| 芯体尺寸： | 8-位 |
| 速度： | 20MHz |
| 外围设备： | POR，WDT |
| 输入/输出数： | 12 |
| 程序存储器容量： | 768B（512 x 12） |
| 程序存储器类型： | 闪存 |
| RAM 容量： | 25 x 8 |
| 电压 - 电源 (Vcc/Vdd)： | 2 V ~ 5.5 V |
| 振荡器型： | 外部 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 20-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 638 (CN2011-ZH PDF) |
| 配用： | AC164307-ND - MODULE SKT FOR PM3 28SSOP AC164014-ND - MODULE SKT PROMATEII 44PQFP |
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PIC16F5X
DS41213D-page 38
2007 Microchip Technology Inc.
8.2
Watchdog Timer (WDT)
The Watchdog Timer (WDT) 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 have been stopped, for
example, by execution of a SLEEP instruction. During
normal operation or Sleep, a WDT Reset or Wake-up
Reset generates a device Reset.
The TO bit (STATUS<4>) will be cleared upon a
Watchdog
Timer
Reset
The WDT can be permanently disabled by program-
ming the Configuration bit WDTE as a ‘0’ (Section 8.1
“Configuration Bits”). Refer to the PIC16F54 and
PIC16F57 Programming Specifications to determine
how to access the Configuration Word. These
documents can be found on the Microchip web site at
www.microchip.com.
8.2.1
WDT PERIOD
An 8-bit counter is available as a prescaler for the
Timer0 module (Section 7.2 “Prescaler”), or as a
postscaler for the Watchdog Timer (WDT), respec-
tively. For simplicity, this counter is being referred to as
“prescaler” throughout this data sheet.
The PSA and PS<2:0> bits (OPTION<3:0>) determine
prescaler assignment and prescale ratio (Section 3.4
The WDT has a nominal time-out period of 18 ms (with
no prescaler). If a longer time-out period is desired, a
prescaler with a division ratio of up to 1:128 can be
assigned to the WDT (under software control) by writ-
ing to the Option register. Thus time-out, a period of a
nominal 2.3 seconds, can be realized. These periods
vary with temperature, VDD and part-to-part process
variations (see Device Characterization).
Under worst case conditions (VDD = Min., Temperature
= Max., WDT prescaler = 1:128), it may take several
seconds before a WDT time-out occurs.
8.2.2
WDT PROGRAMMING
CONSIDERATIONS
The CLRWDT instruction clears the WDT and the
prescaler, if assigned to the WDT, and prevents it from
timing out and generating a device Reset.
The SLEEP instruction resets the WDT and the
prescaler, if assigned to the WDT. This gives the
maximum Sleep time before a WDT Wake-up Reset.
FIGURE 8-1:
WATCHDOG TIMER
BLOCK DIAGRAM
TABLE 8-1:
SUMMARY OF REGISTERS ASSOCIATED WITH THE WATCHDOG TIMER
Note:
The prescaler may be used by either the
Timer0 module or the WDT, but not both.
Thus, a prescaler assignment for the
Timer0 module means that there is no
prescaler for the WDT, and vice-versa.
M
U
X
Note
1:
T0CS, T0SE, PSA, PS<2:0> are bits in the
Option register.
Prescaler
Watchdog
Timer
WDTE
PSA(1)
1
0
8-to-1
MUX
To TMR0
MUX
PSA(1)
WDT Time-out
01
From TMR0 Clock Source
PS<2:0>(1)
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
MCLR and
WDT Reset
N/A
OPTION
—
T0CS
T0SE
PSA
PS2
PS1
PS0
--11 1111 --11 1111
Legend: Shaded cells not used by Watchdog Timer, - = unimplemented, read as ‘0’, u = unchanged
相关PDF资料 |
PDF描述 |
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相关代理商/技术参数 |
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| PIC16F54T-E/SO | 功能描述:8位微控制器 -MCU .77KB 25 RAM 12 I/O Ext Temp SOIC18 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 |
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| PIC16F54T-I/SO | 功能描述:8位微控制器 -MCU .77KB 25 RAM 12 I/O Ind Temp SOIC18 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 |
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