Design Of PCIE Data Acquisition System Based On FPGA

The foundation of testing technology is formed with data acquisition and processing technology, sensor technology, signal processing technology, and PC technology. As the premise of automated detection, The data acquisition and processing technology in the entire digital system are in a particularly important position. For the complex nuclear magnetic resonance (NMR) system equipment, the automatic test is especially necessary. Because of the particularity of the NMR imaging system, and the special requirements of collecting data, it is needed to set sampling points and interval according to different requirements of various pulse sequence. It is also needed to set different sampling rate according to signal bandwidth. Then the system collect the imaging data for processing, and finally reconstructe the image and show. Therefore this paper discusses the data acquisition system with specific applicated in NMR imaging based on the existing sampling technology.The PCIE data acquisition card based on FPGA is disigned from two aspects of hardware and software, and the project design is finished. The software design is based on the control core. It includes FPGA interface control and digital signal processing design. The FPGA capture the data through the Altera GXB IP core, and the communication protocol is made according to actual. The digital signal processing module will filter data through the CIC filter. The data is stored the DDR2 SDRAM. The transport interface is designed with PCIE standard. The logic control interface is completed with FPGA IP resources.The hardware is devided into FPGA peripheral configuration circuit, DDR2 interface circuit, PCIE interface circuit module. It is configured by Flash. The layout depend on the PCIE pin requirements.In the DDR2 interface circuit module the communication between the DDR2 chip and the FPGA on board is determined by the driver, the receiving voltage standard end of the DDR2 chip, and port types. The eye test is carried out for the characteristics of each module interface circuit. The communication quality of the card is analyzed, and the schemetic is optimized.In the test, the FPGA loadeding with the flash, the extraction filtering to high speed digital signal, caching data through DDR2 SDRAM, all kinds of interface and control logic work well. System test results show that the data acquisition system can reconstruct image accuratlly. The design has laid a good foundation of imaging for engineering realization of NMR imaging system.