Abstract: An electronic flow meter includes a magnetic sensor, phase-A and phase-B drivers, a phase-A comparator, a phase-B comparator, a two-phase encoder, and a rotational speed timer. The two-phase encoder determines a normal/reverse direction where the impeller is rotated based on event signals sampled by the phase-A and the phase-B comparators, respectively, causing a counter to count up or to count down according to the normal/reverse direction as determined, thereby outputting an event count signal. The rotational speed timer calculates a rotational frequency of the impeller from the event count signal outputted by the two-phase encoder and sets frequencies of respective sampling signals of the phase-A and the phase-B comparators at a time when the rotational frequency of the impeller is measured next, and respective drive periods of the phase-A and the phase-B drivers in accordance with the rotational frequency of the impeller as calculated.

Abstract: An electronic flow meter includes a magnetic sensor, phase-A and phase-B drivers, a phase-A comparator, a phase-B comparator, a two-phase encoder, and a rotational speed timer. The two-phase encoder determines a normal/reverse direction where the impeller is rotated based on event signals sampled by the phase-A and the phase-B comparators, respectively, causing a counter to count up or to count down according to the normal/reverse direction as determined, thereby outputting an event count signal. The rotational speed timer calculates a rotational frequency of the impeller from the event count signal outputted by the two-phase encoder and sets frequencies of respective sampling signals of the phase-A and the phase-B comparators at a time when the rotational frequency of the impeller is measured next, and respective drive periods of the phase-A and the phase-B drivers in accordance with the rotational frequency of the impeller as calculated.

Abstract: A microcomputer is realized having a built-in SIO which is able to correspond to a LAN which requires strict timing control and also correspond to a high speed serial communication. A counter supplies.a clock signal for data shift to an SIO register which performs serial-parallel conversion and vice versa. Two D flip-flop circuits detect the rise of an SRDY signal, an input signal expressing the start of transmission, and give the counter a reset signal.

Abstract: An analog/digital conversion circuit capable of digital conversion of an analog voltage higher than a reference voltage, by converting an excess of the analog voltage over the reference voltage in result of a comparison with a comparison voltage derived by dividing tile reference voltage, and by setting a digital value of one place up the highest digit place of the digital values obtained as a result of the comparison with the comparison voltage to be 1 (one).