Based on MCS Control Design and Implementation of Digital Pressure Gauges
Abstract: This paper introduces a precise digital pressure gauge of hardware and software implementations. The method with atmospheric pressure through the pressure sensors, the corresponding analog voltage value, and after V / F transform input to the microcontroller for processing to real-time display the corresponding pressure values. Using the method described in this article digital pressure gauge made and easy to carry, simple operation, high accuracy, full compliance with design requirements.
1. Introduction
Pressure Gauge is the use of pressure-sensitive device under test pressure will be directly transformed into easy detection, transmission of current or voltage signal, and then through the subsequent processing circuitry and real-time display of a device. The core component of which is the air pressure sensor, which monitors the pressure in the size, control pressure changes and physical parameters of the measurements plays an important role. Digital pressure gauge of the pressure sensors used are basically relying on the pressure changes of different heights to get the pressure value.
Meteorology studies have shown that in the vertical direction, atmospheric pressure decreases with height increase. For example, in low-rise, each rising 100m pressure to lower 10hPa; in 5 ~ 6km of high-altitude, height for each additional 100m, pressure will be reduced 7hPa; and when a high degree of further increases, that is 9 ~ 10km altitude, the height of each additional 100m, pressure will be reduced 5hPa; Similarly, if there was a downward air flow, the pressure will increase; if there is an upward air flow, the role of the air column at the bottom of the air pressure is reduced. General to act on the unit area on the weight of the air column is called atmospheric pressure
2. The Structure of Digital Pressure Gauge
One pressure sensor is used to convert the measured pressure voltage signal; with the V / F converter can put pressure sensor output voltage signals into a certain frequency pulse signal; in order to use microcontroller to receive the pulse signal and in accordance with per unit time within the pulse number, voltage and frequency based on a linear relationship to calculate the pressure corresponding to the value, in the end MCU controlled by the LED display.
The digital pressure gauge of pressure sensor can be accurately measured within the linear range of the corresponding pressure values. Be explained is that its measured value is the absolute pressure values. Digital pressure gauge of this study the technical indicators are as follows:
● measuring range: 300hPa ~ 1050hPa;
● Accuracy: 0.1% FS (20 ℃);
● Display accuracy: 0.1%, from four 8-segment LED display of;
● Operating temperature range: 0 ~ 85 ℃;
● Supply voltage: 9V.
3. System Implementation
In the system building process, the need to consider the stability, complexity, cost and ease of debugging and other factors. Modules there is no complex signal transmission, and interference with very little, so overall system more stable.
Pressure Sensors
Digital pressure gauge of pressure sensor in the central position occupied. Designed according to measurement accuracy, measuring range, temperature compensation for measuring absolute pressure values, and several other performance indicators to select the air pressure sensor.
As the digital pressure gauge shows the absolute pressure values, and therefore need to select the value of the pressure measuring absolute pressure sensor. Meanwhile, in order to simplify the circuit, improving stability and anti-jamming capability, requested that the air pressure sensor with temperature compensation should be.
To this end, I use Motorola’s MAX4100A pressure sensor to measure the absolute pressure values. The sensor temperature compensation range of -40 ~ +125 ℃; pressure range of 20kPa ~ 1050kPa; output voltage signal (Vs = 5.0V) range of 0.3 ~ 4.65V; measurement accuracy of 0.1% VFSS, at the same time In the 20kPa ~ 1050kPa good linearity when the specific output relationship is as follows:
Ｖｏｕｔ＝Ｖｓ(０．０１０５９ Ｐ－０．１５２８) Vout = Vs (0.01059 P-0.1528)
Japan launched a long-term stability of the Vaisala excellent Digital Pressure Gauge
Vaisala (Vaisala, Headquarters: Tokyo) launched in April 2008 Digital Pressure Gauges “PTB330″. Determination of the range of 50 ~ 1100hPa, or 500 ~ 1100hPa. High-precision models can ± 0.15hPa accuracy determination. A year’s average error of ± 0.10hPa. Request for determination of accuracy and long-term stability of the industrial and aviation use. Specifically, high-precision measurement can be used to want to pressure of the occasion, such as using laser interferometer for measurement, as well as the engine testing in the exhaust gas analysis.
Products that can be embedded in a ~ 3 silicon capacitive absolute pressure sensor “BAROCAP”. If you use multiple sensors, pressure gauges, the determination of the value of the sensor can be compared with each other to determine whether the differences in the set of its range. In this way, can improve the reliability of measured values to easily grasp the pressure gauge to maintain and re-calibration date.
Measurement data not only to a numerical display, but also in order to observe trends in the charts. Chart in the observation process can be automatically updated. The use of special software, you can achieve data transfer to the PC.
MANUFACTURING STEPS OF THE SECOND GENERATION PROTOTYPE
MANUFACTURING STEPS OF THE SECOND GENERATION PROTOTYPE