TW200834049A - An automatic calibrated measuring method for pressure - Google Patents

Abstract

This invention provides an automatic calibrated method for pressure sensor. It mainly comprises a power supply, a microprocessor unit, an A/D converter (ADC), and an amplifier. The power supply includes a basic voltage supply circuit, and a constant-current source. The micro processor unit (MPU) is a microprocessor. When a control code is recorded into its register through program, the MPU outputs a gain code, and a zero-pressure compensation code., The ADC transforms the analog signal from the sensor into corresponding digital signal By means of the combination of the aforementioned circuits, when it is applied for pressure sensing and during the calibration process, according to the sensitivity of the sensor, the output gain code of the microprocessor automatically sets the amplification ratio of the programmable amplifier, and the offset output voltage at zero pressure. The microprocessor also output a zero-pressure compensation code to the digital-to-analog converter (DAC). It outputs a compensative zero pressure value to the zero-voltage output compensator of the amplifier. Therefore, the value inputted to the ADC is at the maximum reading on the scale when the pressure is maximum value Further, the input value inputted to the ADC is the minimum value that is close to zero. By means of this way, the ratio of signal to quantization error is maximum value. Therefore, it improves the precision of the pressure measurement. At the same time, when the device is turned ON, the zero-offset is compensated at the time. It avoids the drift about zero due to the variation of temperature. Eventually, it is exempted from affecting the accuracy of measurement.