System Design, Based On The Conditions Of Dsp + Fpga For Digital Tv Receiver

This paper presents the design of Digital TV Conditional Access System (CAS). On the basis of DSP+FPGA hardware platform, the design of CAS is implemented. DSP is used for the encryption, while FPGA is used for its peripheral circuit.First of all, according to the principle of Digital TV Conditional Access System and the development trends based on the separation of software from hardware, it adopt the framework of DSP+FPGA, ECC and AES algorithm has been applied to the encryption of SK and CW; Based on the study of above, this thesis gives the overall design of CAS, the principle drawing of every module and the PCB design.Secondly, the function of CAS is parted into various modules with the Top-Down designing method, on this basis detailed design of each functional module is finished, and the function simulation of every module is successfully fulfilled with Quartusâ…¡7.2 software. The simulation results show the scrambler module meets the TS scrambling, and the maximum clock frequency of the block cipher and the stream cipher is 229.89MHz and 331.27MHz respectively, the design has large time sequence abundance in the practical transport stream; DSP interface module can satisfy the read/write time sequence of ADSP BF-535; the data processing module can pack the enciphered data.Finally, the program of the encryption algorithms is developed under the principle of structure and modularization. The ECC software adopts the C language and assembly language, so the code of program is simple and the processing time is short. The program of the encryption algorithms is debuged, emulated the program in one ADSP BF-535 EZ-KIT Lite and simulated the multiprocessor program in VisualDSP++3.0. The results indicated that the program of assembly language runs faster than the program of C language, this optimisation makes it run up to 380 clock period faster for 192 bit addition, and 92 clock period faster for 32 bit accumulator; the ECC and AES program meets the design requirements. These above jobs have certain value to the work of the CAS design.