| 摘要 |
PURPOSE:To determine quickly the reciprocal value of the period of an input signal with simple constitution without division by counting the output of a frequency dividing circuit in which a frequency dividing value is set according to the period of the input signal. CONSTITUTION:An input signal A triggers a monostable multivibrator 3 with a waveform shaping circuit 2, and a counter 6 counts the clock pulses CP1 from a generation circuit 1 for clock pulses after the counter is set by an output signal E. A programmable frequency dividing circuit 5 divides clock pulses CP2 with the count value (n) of the counter 4 as a frequency dividing value, and inputs the same to a counter 8. On the other hand, monostable multis 6, 7 are triggered by the leading edge of the pulse CP1 at every generation of said pulse and the count value N of the counter 8 is latched in a latch circuit 9; at the same time, the counter 8 is reset. When an output signal C is generated again, the counter 4 is reset, and a latch circuit 10 latches the output of the circuit 9, from which the value proportional to the reciprocal of the period is outputted. |
