參數(shù)資料
型號(hào)： SST89V516RD-33-I-PIE
元件分類： 微控制器/微處理器
英文描述： 8-BIT, FLASH, 33 MHz, MICROCONTROLLER, PDIP40
封裝： LEAD FREE, PLASTIC, MS-011AC, DIP-40
文件頁(yè)數(shù)： 40/80頁(yè)
文件大小： 934K
代理商： SST89V516RD-33-I-PIE
Data Sheet
FlashFlex51 MCU
SST89E516RD2 / SST89E516RD
SST89V516RD2 / SST89V516RD
45
2005 Silicon Storage Technology, Inc.
S71273-01-000
3/05
7.0 WATCHDOG TIMER
The device offers a programmable Watchdog Timer (WDT)
for fail safe protection against software deadlock and auto-
matic recovery.
To protect the system against software deadlock, the user
software must refresh the WDT within a user-defined time
period. If the software fails to do this periodical refresh, an
internal hardware reset will be initiated if enabled (WDRE=
1). The software can be designed such that the WDT times
out if the program does not work properly.
The WDT in the device uses the system clock (XTAL1) as
its time base. So strictly speaking, it is a watchdog counter
rather than a watchdog timer. The WDT register will incre-
ment every 344,064 crystal clocks. The upper 8-bits of the
time base register (WDTD) are used as the reload register
of the WDT.
The WDTS flag bit is set by WDT overflow and is not
changed by WDT reset. User software can clear WDTS by
writing “1” to it.
Figure 7-1 provides a block diagram of the WDT. Two SFRs
(WDTC and WDTD) control watchdog timer operation.
During idle mode, WDT operation is temporarily sus-
pended, and resumes upon an interrupt exit from idle.
The time-out period of the WDT is calculated as follows:
Period = (255 - WDTD) * 344064 * 1/fCLK (XTAL1)
where WDTD is the value loaded into the WDTD register
and fOSC is the oscillator frequency.
FIGURE
7-1: BLOCK DIAGRAM OF PROGRAMMABLE WATCHDOG TIMER
1273 F19.0
WDT Upper Byte
WDT Reset
Internal Reset
344064
clks
Counter
CLK (XTAL1)
Ext. RST
WDTC
WDTD
相關(guān)PDF資料
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
SST89V516RD-33-I-QIF 制造商:SST 制造商全稱:Silicon Storage Technology, Inc 功能描述:FlashFlex MCU
SST89V52RD2 制造商:SST 制造商全稱:Silicon Storage Technology, Inc 功能描述:FlashFlex51 MCU
SST89V52RD2/RD 制造商:SST 制造商全稱:Silicon Storage Technology, Inc 功能描述:FlashFlex51 MCU
SST89V52RD2-33-C-NI 制造商:SST 制造商全稱:Silicon Storage Technology, Inc 功能描述:FlashFlex51 MCU
SST89V52RD2-33-C-NIE1 制造商:SST 制造商全稱:Silicon Storage Technology, Inc 功能描述:FlashFlex51 MCU
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