| 摘要 |
<p>PURPOSE:To detect a runaway of a microcomputer and to reset automatically the microcomputer by forming a resetting circuit by an oscillation circuit and a frequency dividing circuit. CONSTITUTION:When a microcomputer CPU 1 has run away, an output of an oscillation circuit 8 is divided by a frequency dividing circuit 7 and a signal Qn-2 is outputted. This signal is applied to an interruption input INT of the CPU 1, but since the CPU 1 has run away, a prescribed interruption processing by the CPU 1 is not executed. Accordingly, a reset signal of the frequency dividing circuit 7 is not outputted from an input/output port 3, the frequency dividing circuit 7 is brought to count-up, and from the frequency dividing circuit 7, a signal Qn-1 is outputted. This signal is applied to a reset terminal of the CPU 1 through an inverter 5 and a NAND gate 4, and the CPU 1 is reset. In this way, the microcomputer can be reset automatically.</p> |
