Application of FPGA in Intelligent Pressure Sensor Systems 2

Select components based on the system's accuracy requirements

The FPGA chip selected is Altera's Cyclone II EP2C5, featuring 4,608 logic elements (LEs), 26 M4K RAM blocks, and 142 user I/O pins. diode

Pressure sensor adopts PDCR130W, with a pressure range of 0～7 MPa, operating voltage of DC 10～30 V, output of 0～10 V, accuracy of ±0.05% FS, operating temperature range of -40～+125℃, and temperature influence of ±0.015% FS/℃.

The temperature sensor employs a high-precision integrated LM335, with a sensitivity of 10 mV/K, an accuracy of 1°C, and a temperature range of -40 to +100°C.  diode

The A/D converter selected is the 12-bit AD1 with an internal sample-and-hold circuit. It features a conversion time of 10 μs, unipolar input ranging from 0 to 10 V or bipolar input of ±5 V, and can output 12 bits in parallel.

The multiplexer uses the AD7502 four-channel analog switch, with the EN pin configured as the enable signal and the A1A0 pins serving as the channel selection signals.  diode

The output level conversion interface uses the MAX232 chip to achieve the conversion between TTL and RS 232C levels.

2. Methods for Systematic Error Correction

2.1 Correction Methods for Zero Drift and Gain Error

In intelligent instruments, the error correction formula for the error model is:  diode