| 摘要 |
PURPOSE: A software resetting method is provided to reset a SOHO(Small Office Home Office) router system by using a software watchdog, not a special external logic so that it can reduce a cost for constructing a system, and increase a space in a PCB(Printed Circuit Board). CONSTITUTION: The method comprises steps of enabling a clock input into a software watchdog timer by setting 1 at an SWE field in a SYPCR(System Protection Control Register) of a CPU if a general system clock is input into the CPU, making the enabled system clock drive a decrementer, making the decrementer count downward from the maximum value stored in an SWTC field of the SYPCR, stopping the software watchdog if the value stored in the SWTC reaches zero, and then resetting the system by using an NMA(Non Maskable Interrupt) or an Internal Hard Reset. In driving the decrementer, there are two methods. One is that the decrementer is driven under the general system clock, and the other is that the decrementer is driven under the clock into which the general system clock is divided by 2048. One method for driving the decrementer is selected by setting the SWP field. And a value set in an SWRI field of the SYPCR determines the system resetting method between the NMA and the internal Hard Reset.
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