| 摘要 |
PURPOSE:To prevent malfunction due to a noise from occurring by generating a protective signal from a point in time right before a noise generation period until its end and then by temporarily interrupting the arithmetic prosessing of a micro- computer by this signal. CONSTITUTION:When reference position pulse B of rotational position detection circuit 1 rises up to a high level as the rotation of an internal combustion engine advances, channel C1 of programmable timer 3 starts counting clock pulses from micro-computer 1. Once this count value reaches time data for ignition time control, an ingition command pulse is generated and this pulse is applied to monostable circuit 4, which generates a time limit pulse. In concurrence with the ignition operation of ignition control circuit 5 at the rise of this pulse, the time limit pulse is inverted by inverter 9 to hold terminal SS of computer 2 at a low level, and consequently computer 2 stops operating temporarily. Although a strong noise is generated from an ignition system during the above-mentioned period, computer 2 still stops operating, so that malfunction due to this noise can be prevented. |
