1, the characteristics of the USB bus (1)data transmission (2) data transfer rate data transmission (3) articulated a number of USB devices (4) USB interface for the device power supply (5) hot-swappable USB also has some new features such as: real-time communication between the real-time (can be achieved and a device), dynamic (dynamic switching between interfaces), joint (different interfaces can have similar characteristics together) pluripotency (different interfaces can use different modes of supply).
 

2, the structure of the USB interface and a typical application the USB interface pin definitions. USB interface data transmission distance is not greater than 5 meters. USB bus data transfer control of transmission, synchronous transfer, interrupt transfer, and block data transfer. USB HO the ST according to take an external USB device speed and the use of the characteristics of different data transmission characteristics such as control transfer to change the keyboard, mouse properties, interrupt transmission requirements of the keyboard, mouse input data; to change the Display Properties control transfer block data transfer will want to display the data to send to the monitor.
 

3, the device selection: USB 2.0 devices: FX2 series of Cypress's; High Speed ??ADC: TI, LT, AD 'high-speed (of 40MSPS ~ 80MSPS) 8-bit ADC series; high precision the ADC: TI, the LT, the AD company's high-speed ( 2MSPS ~ 40MSPS) 12/14-bit ADC series; high-speed DAC: AD, LT company's high-speed (of 40MSPS ~ 80MSPS) 8-bit DAC series; high-speed high-precision DAC: AD, LT (20MSPS to 80MSPS) 12/14 DAC family.
 

4, the main features of the EX-USB FX2 EZ-USB FX2 chip includes an 8051 processor, a serial interface engine (SIE), a USB transceiver, 8.5KB chip on the RA M, 4KB FIFO memory as well as a general-purpose Programmable Interface (GPIF) and FX2 is a fully integrated solution, it takes up less board space and reduce development time. EZ-USB FX2 has a unique architecture, including an Intelligent Serial Interface Engine (SIE), it performs all basic USB functions, freeing the embedded MCU to be used to implement specific functions, and to ensure its continued high performance transmission rate. FX2 also includes two general-purpose programmable interface (GPIF), allow it to "glue then you can connect with any ASIC or DSP, and it supports all common bus standards, including ATA, UTOPIA, EPP, and PCMCIA.EZ-USB FX2 is fully applicable in the USB 2.0, and compatible with USB1.1. the FX2 There are three kinds of packages: SOPP of 56 feet, 100 feet TQFF (thin quad flat pack), 128-pin TQFP pin number difference is that the input and output pin number different to requirements for different applications.