在可靠性要求较髙的嵌入式系统中，经常加入看门狗（Watchdog）电路。以下关于看门狗技术的叙述中，正确的是（）。
- A.看门狗技术由硬件独立实现，无需软件干预
- B.只要程序正常运行，看门狗就不会引起系统复位
- C.看门狗的定时周期一般应小于软件运行周期
- D.应用程序异常会使得看门狗超时，导致系统复位
正确答案及解析
正确答案
解析
看门狗电路是一个独立的定时器，有一定时器控制寄存器，可以设定时间。当系统工作正常时，应用程序在到达时间之前要置位（喂狗），表明程序正常运行，如果没有置的话，就认为是程序跑飞，看门狗电路发出RESET指令，迫使系统自动复位而重新运行程序。看门狗的主要作用是防止程序跑飞或死锁。看门狗的定时周期一般应大于软件运行周期。在软件程序运行过程中需要定时修改定时器的计数值（俗称“喂狗”），只要程序正常运行，定时器就不会溢出。若由于软件异常等原因使软件程序不能在看门狗定时周期内修改定时器的计数值，定时器将会产生溢出（或超时），引发系统复位中断，使系统得以重新运行。
包含此试题的试卷
你可能感兴趣的试题
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答5处
-
- A.sensor
- B.searching
- C.service
- D.source
- 查看答案
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答4处
-
- A.low-level
- B.low-cost
- C.high-cost
- D.high-performance
- 查看答案
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答3处
-
- A.19th
- B.20th
- C.21th
- D.22th
- 查看答案
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答2处
-
- A.path
- B.Internet
- C.route
- D.switch
- 查看答案
The Internet of（ 1）（IoT） describes physical objects that are embedded with Sensor，processing abilities，softwares，and other technologies that connect with other devices and systems over the （ 2） or other communication and exchange data networks .Over the past few years, IoT has become one of the most important technologies of the （ 3 ） centuryWe can connect objects to the Internet via embedded devices. By means of（ 4） computing, the cloud, big data, and mobile technologies, physical things can share and collect data with minimal human intervention. Traditional fields of embedded systems，wireless （ 5） networks （WSNs），control systems，automation, independently and collectively enable IoT.回答1处
-
- A.this
- B.thing
- C.think
- D.things
- 查看答案