| 摘要 |
<p>PURPOSE:To prevent the occurrence of an error in time by correcting counting time of a calender IC based on the counting time of the output clock of a CPU crystal oscillator. CONSTITUTION:A CPU 1 is set so as to read out time from a calender IC 2, store it in a memory 6 and issue an interrupt signal iNT to the counter IC 2 one minute after the read-out. At the same time, the CPU 1 reads a free counter value 5a at that time out of a free counter 5, stores it in the memory 6 and waits for the interrupt from the calender IC 2. After the generation of the interrupt, the free counter value is read out of the free counter 5, and the time corresponding to one minute of the calender IC 2 can be obtained with a value based on a CPU clock. When the error is detected accordingly, the accumulated value of the error is stored in the memory 6. When it reaches the minimum unit of the time error which permits time change, the time is changed as soon as the accumulated value reaches a second when the time change of the used calender IC 2 is available in seconds, for instance.</p> |
