| 摘要 |
PURPOSE:To send a correct count quickly even when no leading of a timing signal is detected by presetting the 1st initial value at the leading of the timing signal inputted externally and presetting the 2nd initial value at the trailing. CONSTITUTION:With a timing signal A inputted through a switch 3, since a detection output from a leading detection section 2 is fed to a counter 1 via a NOR circuit 5, the 1st initial value selected by a selector 6 is preset to the counter 1 and the count is started by using a clock(1). After a time elapses, suppose that an asynchronizing timing signal B is inputted with the switch 3 changed over, the trailing of the signal B is detected by a trailing detection section 4 and the detected output is fed to the counter 1 via the NOR circuit and the 2nd initial value (c) is preset to the counter 1 via the selector 6 driven by the said output and the countr starts counting from the said value. Thus, a correct output is sent from the counter without awaiting the leading of the next timing signal.
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