Reasearch And Design Of A Function To Extend The Range Of USB

USB is a very popular bus standard today, and more and more USB-supported-peripherals have been developed. In 1998, USB 1.1 protocol specification was released, and it could support a low speed of 1.5Mbps and a full speed of 12Mbps. In 2000, USB2.0 was released, and it could support a more high speed of 480Mbps, which was 20 times faster than USB 1.1. But as a popular bus standard, it only supports a 5-meter-long cable. This is a big barrier. Though we can use 5 in series Hubs to prolong it to 30 meters longer, it can't meet our demand sometimes. So it is a very meaningful work to develop a function to extend the range of USB peripherals.In this thesis, a solution based on USB 1.1 protocol is introduced. A local extend equipment (LEX) is placed at the end of the host, and a remote extend one (REX) at the end of the peripheral, and the two units are interconnected by the category 5 Unshielded Twisted Pair (UTP) cabling. At the same time, we adjusted the USB protocol of LEX and REX, through which the peripheral may work well. Firstly, the architecture of this solution is discussed, then the function and pins design of each block are introduced, and also the entire circuit diagram of the system is shown. Secondly, the implementation of each block is discussed in detail, and the source code in Verilog HDL and the simulation results are also given. Based on USB 1.1, the protocol design for LEX and REX is chiefly discussed, and the source code in Verilog and its simulation results are also given. Finally, advantages and disadvantages of this system are summarized, and possible solutions are put forward.