Rresearch Of USB-based Virtual Oscillograph

With the development of times, The measuring instrument is being developed in the direction of the virtual instrument(VI), the virtual oscillograph has wide use especially, it can not noly realize the function of the traditional oscillograph , but also store , reproduce , analyse , deal with the wave form etc.This thesis has designed the circuit of virtual oscillograph acquisition and USB communication with such chips as AT89C52 , EPM7128S , TLC5510 and PDIUSBD12 etc,and programmed the software of host with VC ++. The thesis has introduced Specification Revision 1.1 of USB at first, including electric and Mechanical of characteristic ,data packet Formats , data flow model , device Characterizations. Then, according to the architecture of USB1.1 and characteristics of PDIUSBD12 , has programmed the firmware of USB with C51, have explained the workflow of each endpoint of PDIUSBD12 especially.The design of the hardware circuit of virtual oscillograph is a focal point of the thesis, has introduced the relevant principles and characteristics of PDIUSBD12 , TLC5510 , EPM7128S in detail , have designed the hardware circuit. According to the programme amplification principle, utilize CD4051 and LF356 to design the programme-controlled amplifier , has realized 7 are gained grade; According to function and principle of TLC5510 sample circuit , has realized at most sampling speeding up to 20MS/s; According to the principle of USB, has designed the interface circuit of USB, through the firmware programme, has realized normal USB communication; According to demand of signal acquisition and data transmition,has combined EPM7128S with VHDL language to design quasi-dma auxiliary control system, has accelerated the transmission speed greatly. Finally, has provided the method of emulation and debugging of the circuit. Combine with hardware circuit, the realization of oscillograph interface on PC is equally the main research work of the thesis. So, in chapter five of this thesis , has introduced low-layer USB interface programme of host and the design of operating platform respectively. According to WINDOWS API mechanism, interface programme proceed from GUID in the driver, explain how to obtain USB device and how to deal with writing and reading operation of device step by step. Design of operating platform , utilize characteristic of formview in VC ++, acquisition datum are stored and processed, carry on overall arrangement to oscillograph interface , has realized...