The Design And Realization Of AOS Synchronous Transmitter Based On USB2.0

This paper particularly describes the design&implementation of AOS Synchronous Transmitter based on the USB2.0 Bus. The background of the subject is that the CCSDS (Consultative Committee for Space Data Systems) has designed AOS (Advanced Orbiting System) for manned space flight. By using AOS, which can transmit data bidirectionally and symmetrily between the space system and the ground system to serve for customers.Nowadays, each spaceflight courtry is gradually adopting the AOS data standard. Therefore, the research of the AOS key equipments-Synchronous Transmitter is very significant.Synchronous Transmitter works on the AOS physics layer, which is taking VCA (Virtual Channel Accessing layer) 's VC-PDU (Virtual Channel-Protocol Data Unit) with the CCSDS provision of 4 bytes synchronous code 1ACFFC1D, and then sends the data out serially(AOS demarcation function).When top layer has no data,Synchronous Transmitter sends empty synchronous data(functiong of filling).This design uses Cypress's EZ-USB FX2 CY7C68013 chip which supports USB2.0 protocol standard to take on the USB interface chip of Synchronous Transmitter. With Keil C51 in uVision2 development environment, this paper accomplish design and program of firmwave which accords with basic requires of Synchronous Transmitter, and concretely adopt some techniques such as bulk transmission mode, endpoint triple buffered, transmission of bit synchronous impulse and bit data with timer ISR(interrupt service routine), software FIFO, LED display with I2C bus, and participate in fulfilling drivers of firmware auto download in the end.Through test, Synchronous Transmitter has achieved principiumly basic principle design and verification which this subject requires.