| 摘要 |
PURPOSE:To obtain accurate time for a long period by calculating an error in time and its error rate with a correction signal and correcting the program for the frequency division number of a crystal oscillation frequency based on them. CONSTITUTION:A time difference calculating part 4 is provided to calculate the difference between time stored in a time storage device 2 and the current time clocked by a timer device. An error calculating part 5 is provided and inputs an externally inputted correction signal at time when an optional correction is to be made after the time setting to calculate the error between the current time of the timer device and the input time of the correction signal. Then, an error rate calculating part 6 calculates the error rate from the outputs of the time difference calculating part 4 and the error calculating part 5. Then, a frequency division number setting part 7 corrects the frequency division number of a programmable frequency dividing circuit 3 with said error rate and sets it again to hold the correct frequency division number in the timer device, thereby performing correct clocking operation. |
