Research Of Linear CCD Transient Spectrum Data Acquisition System Based On FPGA

Light is an electromagnetic wave of the human eyes can see, also known as thevisible spectrum, and research on spectrum has a history of more than one hundredyears. Being able to detect all spectral lines within the scope of certain wavelength in asingle exposure, the Charge-Coupled Device has been widely used in modern spectralacquisition system due to small size, high sensitivity and flexibility.The linear CCD transient spectral acquisition system with FPGA as the controlcore is proposed in this dissertation to overcome the defect of traditional spectralacquisition system in collecting transient spectrum signal. After a brief introductionabout photoelectric conversion principle of CCD device, linear TCD1304DG imagesensor with electronic shutter function is chosen to be detector according to thecharacteristics of collection objects, then its structure, function and CCD outputcharacteristics are elaborated. On this basis, aiming at CCD output characteristics,AD80066signal processor with correlated double sampling technique is adopted torealize analog front-end processing of output signal and A/D high precision conversion,then send digital data to internal FIFO storage of FPGA for cache and clock domainmatching. With action of readout clock, the processed cache data is transmitted throughUSB2.0interface chip, and then complete the system hardware design. In the systemsoftware design, the timing-driven and control procedures based on FPGA are realizedand fully optimized by hybrid programming of Verilog HDL and schematic. Theremainly includes timing-driven of linear CCD, register configuration and samplinginterface control of AD80066, buffer configuration of FIFO and asynchronous SlaveFIFO write control program of USB in the design. The firmware framework providedby Cypress is employed for USB firmware program, modifying initialization andcustom functions to meet the design requirements. The programs are verified bysimulation in integrated development environment and the waveforms have goodcoherence to actual measurements in circuit board.Finally, the circuit design of the whole system is completted, modular debugging iscarried out for each part in acquisition system, and then actual measurements of the keycomponents are showed and analyzed in the last of the paper. Board-level debuggingresults show that the minimum integration time can reach10μs, and this system hashigher portability and stronger controllability comparing to ordinary linear CCD spectral acquisition system, which will lay foundation for developing acquisition systemwith shorter integration time, higher precision and transmission rate.