| 摘要 |
PURPOSE:To provide a software runaway preventive device capable of simplifying its constitution, lowering a cost and preventing a software switch from being inactive due to runaway of a software or the like in an equipment for controlling plural programs by one CPU. CONSTITUTION:For first and second watchdog timers 13 and 14, when the program is normally operated, a counter is cleared by the interruption routine of key scanning and the interruption routine of mechanical control. Contrarily, when the software runs away, the counter overflows without being cleared, carry signals CRY1 and CRY2 are outputted and thus, unconditional forced interruption signals NMI/are outputted from a NOR circuit 15 to the CPU 1 and the CPU 1 is reset. |
