| 摘要 |
PURPOSE:To minimize the possibility of a watchdog timer is started during a runaway of a program, by writing data from a processor in the watchdog timer only when a selection signal for selecting the watchdog timer is received. CONSTITUTION:A timer controller 2, when receiving watchdog timer selection data, compares it with set data preset in a comparator 3 and when their coincidence is obtained, a selection signal 8 for selecting a watchdog timer 4 is sent to the timer 4. A processor 1 specifies an address of the timer 4 after that to write data, thereby restarting the timer. In this case, the timer inhibits write data from the processor 1 from being inputted to a counter 6 by the condition of an AND circuit 5 unless the selection signal is supplied from the controller 2, so the timer 4 is never started. |
