Software design of the intelligent quartz oscillator vacuum gauge

Many software designs used in the quartz oscillator vacuum gauge, including data sampling, nonlinear curve fitting of air pressure and frequency, temperature compensation in low air pressure introduced are introduced. V/F transition signal fp sampled by singlechip and syntonic frequency fc of the quartz oscillator were obtained and filtered by software. The method of combining time interruption with count interruption of interior pulse was adapted to improve the accuracy. The curve of Pi vs fp obtained by a lot of experiments was divided into four segments for nonlinear curve fitting. When the vacuum value was smaller than 10 Pa, the software would do the temperature-compensating according to the form saved in the microprocessor to widen the lower measurable limit. The experimental results showed that the vacuum gauge had 10%-15% measurement error in the 10-5-10-1 Pa range.