The Development Of Radar Data Generator Based On FX2 And USB2.0 High Speed Transfer Exploration

USB devices have many advantages, such as portable, easily attached, plug and play, etc. They are so popular with the consumers that USB has grown to the main interface for portable storage devices, multimedia devices, human interface devices and etc. In the radar ground system, there are many testing devices, which also need to be portable, why don't design them USB devices? It is for the high speed, the data rate of most of these devices has to be more than 40MB/s. Theoretically speaking, it is lower than the highest speed of USB2.0, which is 60MB/s. But in the investigation, at present, the actual data rate of the popular USB devices is hardly more than 30MB/s. The purpose of this paper is by testing the actual transfer rate limit of USB2.0, to determine if USB2.0 can be used widely in the radar ground system.In order to find how to improve the actual transfer rate of USB2.0 device, I have to acquaint myself with the design process of USB device. So a data generator based on USB2.0 interface was designed firstly. By introducing the design of the data generator, the paper gives a whole instance of USB device development.Finishing the development of the data generator, I did many experiments to study how to improve the actual data rate of the USB device. In the end, the bottleneck of the USB transfer is discovered: if a single endpoint used in a USB device, the bus idle time between two transfers is too long. Further experiments gives that, if two or more endpoints used, the bus idle time between the two transfers of different endpoints is much shorter. And so the idea of multi-endpoint transfer comes out: by using multi-endpoints in a USB device, try to avoid any two transfers from the same endpoint abut against each other, the transfer rate can be increased markedly. Adopting this idea, the maxim speed in the experiments comes to 49.552MB/S, which is close to the transfer rate limit of the USB2.0 transfer. In the paper, the process of the experiments and the implement means of the multi-endpoint transfer are described in detail.