| In the instrument test system,multi-function I/O modules have multiple functions such as analog I/O,digital I/O,programmable I/O,and are widely used in portable test equipment and automatic test systems in industrial testing and other fields with the advantages of small size and flexible configuration.Thesis relies on the hardware platform of multi-function I/O module developed by the national production of devices,which is a mixed-signal test module.PXIe(PCI extensions for Instrumentation Express)bus is used for software and hardware communication,which has the characteristics of high transmission rate and good electrical performance.The thesis analyzes and combines the functional requirements of hardware,proposes the overall software scheme,designs and implements the PXIe communication-based kernel driver based on the domestic Kirin Linux operating system platform,designs partial the virtual instrument software architecture(VISA)library based on the domestic operating system,standardizes the multi-functional I/O driver interface,and completes the upper computer software design with high accuracy and simple style,Finally,a stable and reliable calibration scheme is realized according to the requirements of measurement accuracy error.The software design of the thesis adopts the layered design idea.From the bottom driver to the upper application software,the thesis mainly completes the following research1.The kernel layer driver design and implementation.In order to meet the requirements of hardware transmission,the kernel layer driver implements XDMA driver that conforms to the PXIe protocol standard,and can perform interrupt processing,register reading and writing,DMA data transmission,etc.The driver reading and writing,transmission rate,reliability,etc.It is verified by designing a test program,and finally the conclusion that the driver meets the design requirements is reached.2.The design and implementation of application layer driver.The driver design of the thesis considers multi-platform compatibility,and develops partial VISA library under Linux system to provide the underlying I/O interface.When the application software platform changes,the system code can be transplanted to the new platform without making too many changes to the instrument driver.The multifunctional I/O programming interface standard is designed and standardized to make the application program completely independent of hardware.3.The design and implementation of multi-function I/O host computer based on Qt.According to the different functions of multi-function I/O module,it is divided into several functional modules,namely analog I/O module,digital I/O module,programmable I/O module,etc.In addition,in order to facilitate the use of functional modules,auxiliary modules are designed.For example,a module designed for historical data caching.4.Design and implementation of calibration module.For the analog I/O function,the causes of DC voltage measurement error in the hardware design are analyzed,and the measurement error calibration and temperature compensation calibration algorithms are designed to improve the DC voltage measurement accuracy.Through the design and implementation of the above contents,the thesis finally completed the software design of multi-function I/O module based on PXIe of Linux.After the function test and reliability test,it is concluded that the multi-functional I/O software designed in this project meets the design requirements. |
