| 摘要 |
PURPOSE: A watchdog timer of a program controlled by a software is provided to reduce the space of a board and the cost of production by implementing the function of a watchdog timer in an ASIC(Application Specific IC) as a logic and to improve the function of a man-machine interface and the operability of a user by making possible the time setting and control through software control. CONSTITUTION: The watchdog timer(100) comprises a time duration setting register(110), a time duration read logic(120), a counter load/restart logic(130), a counter(140), a flip-flop(150), a control logic(160), and a counter enable logic(170). The time duration setting register sets necessary time duration and outputs the duration time value. The time duration value is read by the time duration logic. With input of a counter enable control signal, the counter enable logic outputs a counter enable signal. The counter load/restart logic outputs a counter load signal. The counter outputs a counting value and counts time depending on reset time duration. The flip-flop reduces the distortion of the counter value. The control logic outputs a watchdog write register control signal, a watchdog read control signal, a counter enable control signal, and a CPU-check-in signal.
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