The Design Of PXI Digital I/O Module

Along with the development of Electronic Science and technology,the test requirements of radar and telecommunication equipments are increasing.Normally,signal can be divided into analog signal and digital signal.Taking on an irreplaceable role in a testing system,digital I/O module is used as the communication module of digital signal generation and acquisition.Now,the third generation of ATS based on PXI modules dominates the ATS field.And therefore,according to the actual testing needs in fields of radar and telecommunication,this subject designs a PXI digital I/O module,which has isolation performance,coupled with high speed and deep storage characteristics.This paper analyzes the research status and application scenarios of PXI digital I/O module in the first place.According to the design requirements of this subject,this paper presents a complete hardware design scheme through the feasibility analysis of building the hardware platform of PXI digital I/O module.Coupled with 32 isolated input channels and 32 isolated output channels,this digital I/O module is qualified in the signal acquisition function with a maximum data transfer rate of 50 Msps and the graphic data output function with data transfer rate up to 50 Mbps.To meet the testing requirements in aerospace and industrial fields,this module can also equip each of the 32 isolated output channels with a 30 V high voltage output.In the first place,this paper analyzes the power waste of the circuit to make sure the system can work normally.This design chooses TLP 2367,the latest high-speed photocoupler of Toshiba,to realize the isolation of 64 I/O channels and uses a 2 Gb DDR2 SDRAM to meet the demand of storage depth.The PXI interface is realized by FPGA combined with PCI 9054.This module is basing on six-layer PCB stackups,with single end impedance set up as 50 ohms.The design of the DDR2 SDRAM refers to the given requirements of Micron and also meets the design specification of high speed digital circuit.The logic design in FPGA is consisted of PXI interface,DDR2 controller based on IP core,FIFO and I/O controller.This paper gives a complete design method of FPGA functional logic.User can couple the interface of each module to meet the needs in different testing environment.Through the debugging,this PXI digital I/O module meets all the expected I/O features.