| 摘要 |
<p>PURPOSE:The keep the normal working of a CPU even with the unstable power supply voltage by connecting a voltage detector to an analog port of the CPU for addition of a reading process of the analog port. CONSTITUTION:When the power supply voltage VCC drops and crosses the service interruption detecting voltage V1 of a voltage detector, the output voltage 21a is inverted to 'H' from 'L' and an interruption signal iNT is applied to a CPU 1. The CPU 1 carries out an interruption processing operation and reads the level of the voltage 21a through the initial process of a main routine. In case the voltage 21a is set at 'H', an LED is turned on to show the abnormality of the voltage VCC. While the main body part of the main routine is processed when the voltage 21a is changed to L. Thus the CPU 1 can keep its normal working even though the voltage VCC drops and the service interruption is recovered with no output of a reset signal 5a.</p> |
