| 摘要 |
<p>PURPOSE:To increase the lifetime of a battery without deteriorating the processing ability of a CPU by actuating the CPU with a basic clock of a low frequency when a load factor is small. CONSTITUTION:A CPU 1 performs an idle process and outputs the idle pulses from an I/O port 3 via a bus line 5. A CPU load detecting part 4 counts these idle pulses and compares the count value with the 1st and 2nd comparison values when a clear/latch signal is inputted from the CPU 1. Then a selection signal is outputted to a clock switch 2 for selection of a basic clock CLK1 of a comparatively low frequency when the count value is larger than the 1st comparison value. Meanwhile a selection signal is outputted to the switch 2 for selection of a basic clock CLK2 of a comparatively high frequency when the count value is smaller than the 2nd comparison value which is smaller than the 1st comparison value. Thus it is possible to control each part and to increase the battery lifetime without deteriorating the processing ability of the CPU 1.</p> |
