Research And Development Of High-speed Data Acquisition Card Based On PCI Bus And Dual Port Buffer

Data Acquisition (DAQ) refers to a process of collecting information automatically from detector and other tested units. It is one of the tendencies of current computer application to extend the computer function with the extension slot to constitute data acquisition system. Data acquisition card get sampled data with built-in data sampling circuit, store and process them with the aid of the various resources of the computer, which therefore can greatly simplify the circuit design, and improve the resource utilization ratio. High-speed data acquisition card is required to be able to sample transient signal with high-speed, and then send real time the sampled data to CPU. In order to meet this requirement, relevant measures need to be adopted to ensure real time and effectiveness of the data.The key parts to realize data acquisition with high-speed are as follows: High-speed A/D conversion and real time data transmission. Firstly high-speed A/D chip is taken to ensure the effective sampling of transient signal; and then buffer the sampled data by dual port memory; during the process of acquiring and caching the sequential data, the computer, under the control of device driver and trough the high-speed PCI BUS, uses highly efficient DMA transmitting mode to access the existential data from dual port RAM and put it into the computer memory to ensure permanent storage and/or analysis processing. All the functions mentioned above are achieved under the control and coordination of CPLD and WDM drivers. After adopting these measures, Data Acquisition card can acquire the transient outside signals and transmit them to the computer with fast speed.This Data Acquisition card incorporates organically the several techniques which are the most advanced at present: adopt 2 levels PGA and high-speed A/D conversion chip to acquire the signals; use dual port RAM to buffer the data; make use of CPLD to accomplish the logic and sequence control of Data Acquisition card; by special master PCI bus interface chip bridges local bus and PCI bus; use WDM drivers that supports PNP function to control hardware work of Data Acquisition card by means of combination DMA and interrupt, to provide application with bottom service. All these measures efficiently make sure of the reliable achievement of the real time task.