1. overview
3D-MEMS silicon capacitive pressure sensor is famous for its high precision, small size and ultra low power consumption. The power consumption of this kind of sensor is very low, which makes it have incomparable advantages in the battery powered equipment.
The 3D-MEMS silicon capacitive pressure sensor, through the differential operation and nonlinear correction and temperature compensation of the microprocessor, eliminates the effect of changes in atmospheric pressure, water pressure in order to achieve high precision measurement, temperature measurement and storage.
All stainless steel integral structure design, waterproof design 100% of the long-term use of water, water pressure sensor, pressure sensor, battery and circuit are sealed in a stainless steel casing. 22mm is the international standard size, can be installed in deep application and other application field, groundwater, rivers, lakes, reservoirs and other long-term monitoring and forecasting of geological disaster comprehensive utilization.

2. characteristics
A. silicon capacitive absolute pressure sensor based on 3D-MEMS technology, long-term use without zero drift;
B. sensor has very low power consumption and consumes 25uA of total current at normal operation;
C. integrates water level and temperature measurement into one, which is suitable for water level monitoring and comprehensive utilization of geological disasters;
Intelligent switching of D. internal and external power supply;
C. uses 16 bit mixed signal microprocessor technology to complete the digital linearity and temperature error compensation of water level sensor, with high precision and high resolution;
D.64Mbi large capacity flash storage, automatic recording data for a long time;
E. water level range: 10 meters, 20 meters, 40 meters, 70 meters, 100 meters;
F. overload capacity: greater than 10 times full scale;
The working temperature range of G. is -40~125 centigrade, resolution is 0.01, and the precision is 0.2.

3. working principle and process
Using a new type of silicon capacitive absolute pressure sensor to measure the depth of water, pressure sensor and atmospheric pressure sensor pressure signal has a high accuracy and resolution. Two pressure sensors and linear temperature error of digital compensation, compensation parameters stored in the nonvolatile memory, to ensure the safety of data.
According to the user set the acquisition cycle, activation system from sleep mode, MCU began to work, the temperature and pressure signal through the signal conditioning part was sent to MCU for processing, and then stored in the prescribed format to Flash. You can read the download to use these data reading device through the RS485 interface, the data include: hydrostatic pressure, hydrostatic pressure value, value, temperature, battery voltage, current time, historical data etc..
When the end of the water level, temperature data acquisition and recording system, once again into the sleep mode, MCU and peripheral module to stop working, only the clock module, battery power supply to maintain the accuracy of the clock module, clock. The clock module is responsible for activating the system and continuing to collect and record when the set sampling interval arrives. Each time the reader reads the data from the interface, the system clock is corrected once, to ensure the accuracy of time.
Part of the power management of power management, in order to prolong the battery life, and in the use of the reading device, is responsible for the external power switch in, disconnect the battery and then cut back. The protection circuit is responsible for providing overvoltage protection to the whole system.