| 摘要 |
<p>PROBLEM TO BE SOLVED: To allow even a battery-driven CPU to count pulse data from a flow sensor at high speed without monitoring changes in the pulse data in terms of software, thus reducing battery consumption rate. SOLUTION: First pulse outputs derived from the temperature of gas before it is heated by a heater and second pulse outputs derived from the temperature of the gas after it is heated by the heater are input to a monostable multivibrator circuit 30 from a flow sensor 10, and upon detecting completion of the first and second pulse outputs the monostable multivibrator circuit 30 outputs interrupt signals for indicating the completion of the pulse outputs. A counter 25 counts the pulse numbers of the first and second pulse outputs and then outputs first count data about the first pulse outputs and second count data about the second pulse outputs to a memory 27 at the input of the interrupt signals thereto. The first and second count data are reset thereafter and a flow rate calculating part 29 calculates the flow rate of the gas on the basis of the difference between the first and second count data.</p> |
