An Eight-channel Data Acquisition Module Base On VME Bus

The purpose of the High Energy Physics experiment is to measure the energy momentum,the position and so on of particles .Takes of the Data Acquisition System is to process and analyze the signal which come from the detector. The Data Acquisition is a pivotal part of digitization of nuclear instruments and an absolutely necessary component of Digital Signal Processing. The signal's pulse height is in scale of the particle energy; therefore measuring the signal pulse height can tell us the energy.This paper discusses an Eight-channel Data Acquisition module based on VMEbus. The module amplifies and filters the signal which come from the detector, and using ADC to sample it to get digital signal, and then send the digital data to FPGA. Emphasizing particularly on describing the principle of how to decade serial data to parallel data implemented by FPGA, including peak finding, pipeline data buffer implementation. At last FPGA sends data to the computer via VMEbus.The overall scheme of the VMEbus Data Acquisition System is given in the paper. System's hardware program has been designed; include analog circuit part, digital circuit part and other hardware circuit interface. Hardware logic of FPGA in system has been designed with Verilog language, and each module also is described in detail; include Verilog language input, logic simulation, design compiler and so on. The data transmission logic design of the VMEbus is accomplished, and A24/D16VMEbus data transfer function is realized using state machine.The test results show that the Data Acquisition system has achieved good performance expected. And its logic functions are full programmable. The conclusion is that it is possible to digitize analog signals with no extra dead time.