| 摘要 |
<p>PURPOSE:To provide a runaway detector which detects runaway only by a CPU without using a reset IC and informs the occurrence of the runaway to the outside. CONSTITUTION:The CPU 1 is an ordinary central processing unit which incorporates a ROM or RAM 2, etc., in addition to a clock mechanism to clock a time. A LED 5 is connected to the CPU 1 via a resistor 4 between an output port 3 and a power source. The CPU 1 clears the clock interruptive timer of the clock mechanism at a fixed period earlier than timer time set on the timer. When the runaway of the CPU occurs, the clock interruptive timer is completed. An instruction to write a constant on the RAM 2 is prepared in a vector interruption destination by such time completion, and it is set so as to be reset after the instruction is executed. The CPU 1 refers to the RAM 2 at the beginning stage of processing after the application of the power source or reset, and makes the LED 5 put on continuously when no constant is stored, and makes it flicker when the constant is stored.</p> |
