Design And Implementation Of Interface Module Of Portable Oscilloscope Based On USB3.0

USB bus technology is widely used in the communication between computers and peripheral devices.The oscilloscope based on the USB interface and using a computer as an industrial computer has become one of the development directions of test and measurement instruments.For data transmission between test and measurement instruments and computers,the USB488 protocol is developed on the basis of the USB protocol.Through the USB488 interface,the computer can issue SCPI(Standard Command Set for Programmable Control Instruments)commands through the application software to achieve program control of the instrument.The purpose of this subject is to design a USB-based oscilloscope interface module,through which the instrument can be controlled by the program-controlled instructions issued by the computer.The main work includes the following aspects:First adopt the overall design plan of "FPGA+USB protocol chip".Choose CYUSB3014 as the USB protocol chip of this design.Carry out interface module hardware circuit design and FPGA logic design.Design the circuit schematic diagram of the interface module;design FPGA logic code to realize the read and write timing control of the GPIF II interface in CYUSB3014,and realize the analysis of custom instructions.Followed by the USB protocol chip firmware programming and the realization of the USB488 interface.The GPIF II interface in the USB protocol chip is configured as a slave FIFO interface mode to accept FPGA read and write control,and a manual DMA channel is set in the chip to buffer and process the communication data between the computer and the instrument.According to the USBTMC protocol,the USB488 interface is realized based on the USB protocol chip.Then design the SCPI instruction set and instruction analysis program suitable for this model oscilloscope.In the USB protocol chip,the instruction set is stored hierarchically in a binary linked list.The preorder traversal method is used to match and access the instruction node,and the instruction processing function is called according to the node code value to realize a specific operation.Finally,the PC-side application software is designed.The application software programs the instrument by issuing SCPI commands;receives and processes the sampled data uploaded by the instrument and the instrument status information,and converts the sampled data into a waveform form and displays it on the software interface.The test and verification results show that the interface module of this subject realizes high-speed data transmission between the computer and the instrument;through the USB488 interface,the computer application software can issue SCPI program control instructions to the instrument;the interface module can correctly parse the SCPI instructions and call function execution Operation;the application software can receive and process the data uploaded by the instrument normally.