| 摘要 |
PURPOSE:To automatically calibrate time by allowing the time of a clock circuit to coincide with the time based on a sine wave signal of predetermined frequency when the difference between the time based on the sine wave signal of predetermined frequency and the time of the clock circuit is the same two or more times at every unit time. CONSTITUTION:A microcomputer (MC)1 receives the clock generated from a quartz vibrator 5 to display the calculated time on a display part 2. When a timer is set, a desired time is inputted to the MC 1 by a switch 4. When a desired time reaches in such a case that the timer is set, the timer is operated to send data, for example, to the microcomputer (MC) 9 of an audio apparatus or to operate a transistor 6 to control a relay 7 to issue a time signal. The MC 1 resets a max. value detection flag and an internal hard counter and extracts a sine wave signal of predetermined frequency at every time detected by a tuner 11 from an A/D input terminal three times at every predetermined sampling time and, when the same error is continuously detected three times, the present time of the block circuit is corrected in synchronism with the sine wave sent out of a broadcasting station. |
