| 摘要 |
PURPOSE:To realize an automatic get-out from a runaway state for a microcomputer, by inserting a part which applies restarting to a circuit into a part of a process routine of a program and then restarting from an interruption routine in case it is impossible to start the circuit due to runaway of the microcomputer. CONSTITUTION:A runaway preventing circuit of a microcomputer is provided with a pulse generating circuit 1, monostable multivibrator 2, differentiating circuit 3 and monostable multivibrator 4. When a program 10 is started, a runaway detecting program 2 detects the runaway at every fixed time. Then the program 10 is executed in the normal mode. In this case, a periodic pulse F1 is generated from the vibrator 2. The pulse F1 is set at a low level when a certain period elapses to give no change to a circuit. When the program has a runaway, the execution is discontinued for a program 12 to produce no pulse F1. Then the output of the vibrator 2 is set at a low level, and the negative pulse is produced from the circuit 3. The vibrator 4 is reset with a pulse F2. Thus the microcomputer gets out automatically from its runaway state. |
