Usb Download Interface Based On The Boundary-scan Test Circuit Design And Realization

With rapid developments of system on chip (SOC), programmable logic devices (PLD), including complex programmable logic device (CPLD) and field programmable gate array (FPGA), can support in-system programmability (ISP) and become more popular in the world. This requires better download cables than before, which are used to program PLDs.This dissertation researches how to design and accomplish universal serial bus (USB) download interface circuit based on IEEE std.1149.1 specification. The logic design of interface circuit is realized in Verilog hardware description language (HDL). Function simulation is finished by ModelSim software. After the synthesis, placing, routing and obtaining delay information by develop tool Quartus II4.0, timing simulation is accomplished by ModelSim software. Schematic and PCB designs of the interface circuit are implemented by protel 99 software.In the logic design, the fundamentals and characteristics of IEEE std.1149.1 specification and USB protocol are introduced first of all. According to Altera's FPGA Cyclone, it analyzes the architecture and JTAG instructions of boundary scan test (BST). Then the dissertation analyzes how to program Cyclone device and offer the scheme of the design which is realized in Verilog HDL by ModelSim and Quartus II software. Finally function and timing simulation are accomplished.In the hardware design, FTDI's FT245BM device is selected to accomplish USB interface. Altera's EPM7064 device is selected to accomplish JTAG interface logic design. At last logic design codes are downloaded into EPM7064 device to test and verify the destign.The test and verification results show that USB download interface circuit based on std.1149.1 specification which is designed can correctly program Altera'PLDs. In addition, the USB download interface circuit has good compatibility and stability.Compared with traditional download cable based on PC' parallel port, the download circuit based PC's USB port has many advantages, such as hot-plugging, compact, rapid, convenient in installing. The products which are like our USB download circuit have been developed overseas, but the price is very high. According to the price, the USB download interface circuit has good ability of competition.