watchdog timer is hitwd. To hold the watchdog timer at bay, make a c" />
參數(shù)資料
型號： 101-0303
廠商： Rabbit Semiconductor
文件頁數(shù)： 48/126頁
文件大?。?/td> 0K
描述： SMARTSCREEN OP7100 DISPLAY
標準包裝： 1
系列： SBC
模塊/板類型： 單板計算機模塊，帶顯示器
適用于相關(guān)產(chǎn)品： 單板計算機
OP7100
28
Hardware
watchdog timer is hitwd. To hold the watchdog timer at bay, make a call to
hitwd
in a routine that runs periodically at the lowest software priority level.
A program can read the state of the WDO line with a call to wderror. This
makes it possible to determine whether a watchdog timeout occurred. The
following sample program shows how to do this when a program starts or
restarts.
main(){
if( wderror() ) wd_cleanup();
hitwd();
...
}
Power Shutdown and Reset
When VCC (+5 V) drops below V
MIN (between 4.5 V and 4.75 V), the
ADM691 supervisor asserts /RESET and holds it until VCC goes above
V
MIN and stays that way for at least 50 ms. This delay allows the system’s
devices to power up and stabilize before the CPU starts.
PFI “Early Warning”
When PFI drops below 1.3 V ± 0.05 V (i.e., DCIN drops below ~10 V),
the supervisor asserts /NMI (nonmaskable interrupt), and allows the
program to clean up and get ready for shutdown. The underlying assump-
tion here is that PFI will cause the interrupt during a power failure before
the ADM691 asserts /RESET.
In order to improve the performance of the power-failure interrupt circuit,
we have added some hysteresis to the power-failure comparator by adding
a resistor, R34, between the comparator input and output pins. R34 can be
found on the 175-0196 and the 175-0211 versions of the OP7100. The
hysteresis prevents the comparator from switching rapidly—and therefore
generating multiple interrupts—when the input voltage is falling slowly.
Once the comparator switches (DC IN falls to approximately 8.5 V), this
feedback holds the input (PFI) low and prevents further interrupts from
being generated. At this point, the 5 V regulator still has sufficient voltage to
keep the processor operating, so that an interrupt service routine can
perform shutdown tasks and “tidying up” before the Vcc line fails. The
comparator will not turn the output (PFO) high until DC IN has risen to
about 9.2 V. The hysteresis will also help prevent any system oscillation in
adverse power supply/loading situations.
The voltage at which the power-failure interrupt occurs may be changed by
adjusting the values of R29 and R30, which are shown in Figure 3-3. To
calculate the values of these components, let V
L be the voltage at which
PFO turns off as DC IN falls, and let V
H be the voltage at which PFO turns
on as DC IN rises.
相關(guān)PDF資料
PDF描述
101-0383 MODULE RABBITCORE RCM2020
101-0435 MODULE RABBITCORE RCM2110
101-0453 MODULE RABBITCORE RCM2300
101-0494 MODULE RABBITCORE RCM2250
101-0518 MODULE RABBITCORE RCM3110
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
10103042SP 制造商:Pentair Technical Products / Hoffman 功能描述:HTR COMP 240V 25W W ADH TIES
1010-3-05-00-00-00-01-0 功能描述:電路板硬件 - PCB PRESS FIT WRAPOST RECPT 3 WRAPS RoHS:否 制造商:Harwin 類型:Shield Clip 長度:9.4 mm 螺紋大小: 外徑: 材料:Beryllium Copper 電鍍:Tin
1010-3-05-01-00-00-01-0 功能描述:電路板硬件 - PCB 200u SN/PB OVER NI 3 WRAPS RoHS:否 制造商:Harwin 類型:Shield Clip 長度:9.4 mm 螺紋大小: 外徑: 材料:Beryllium Copper 電鍍:Tin
1010-3-05-15-00-00-01-0 功能描述:電路板硬件 - PCB 10u AU OVER NI 3 WRAPS RoHS:否 制造商:Harwin 類型:Shield Clip 長度:9.4 mm 螺紋大小: 外徑: 材料:Beryllium Copper 電鍍:Tin
1010-3-05-21-00-00-01-0 功能描述:電路板硬件 - PCB 20u AU OVER NI 3 WRAPS RoHS:否 制造商:Harwin 類型:Shield Clip 長度:9.4 mm 螺紋大小: 外徑: 材料:Beryllium Copper 電鍍:Tin
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