| 摘要 |
PURPOSE:To obtain a synchronizing means which is scarcely influenced by a noise by deviding a frequency of a clock pulse based on a result of a measurement of a power source frequency, and applying a timer interruption to a microcomputer by its frequency-divided pulse. CONSTITUTION:A titled flowmeter is provided with an input counter 10 for counting a pulse Pi from a waveform shaping circuit 9 for picking up a frequency fm of power source 1, a clock counter 11 for counting a clock pulse Pc, and a frequency divider 12 for dividing a frequency of the clock pulse Pc and applying a timer interruption to a microcomputer 5. The power source frequency fm is measured from a count value Ni of the input counter 10, a count value Nc of the clock counter 11, and a period Tc of the clock pulse Pc by the microcomputer 5. In accordance with a result of its measurement, a frequency dividing factor (m) is determined, and set to the frequency divider 12. |
