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USB2.0 Development circuit

Published on Aug 10 2010 // USB based circuits

USB2.0 Development circuit

USB2.0 Development circuit1

USB, stands for Universal Serial Bus ( Universal Serial Bus) , which is the end of 1994 by Compaq , IBM, Microsoft and other companies jointly developed , USB interface, has experienced six years of development, now USB 2.0 version has been developed to . USB2.0 protocol support for all existing USB devices , not only can the PC USB1.1 device into USB1.1 interface, compatible with USB1.1 and in electrical connection on the line . 1, USB bus characteristics (1 ) high data transfer rate (2 ) reliable data transmission (3 ) while multiple USB devices attached (4) USB interface, power supply for equipment (5 ) support hot swap . USB also has some new features , such as: real time ( can be achieved and an effective real-time communication between devices ), dynamic ( can implement dynamic switching between interfaces ) , the joint nature (different and there are similar characteristics Interface can be combined ), pluripotent ( all of the different interfaces can use different power mode) . 2, USB interface, the structure and typical applications USB connector pin definitions shown in Figure 4 . USB interface data transmission distance is not more than 5 meters. USB bus data transmission controlled transmission, synchronous transmission, interruption of transmission, block data transfer . As shown in Figure 5, system , USB HOST according to an external USB device and use features to speed data transmission characteristics of different . Such as by controlling the transmission to change the keyboard , mouse, property , interruption of transmission requests by keyboard , mouse input data ; by controlling the transmission to change the display attribute data transmission through the block will send monitors to display the data . 3 , the device used : USB2.0 Device : Cypress FX2 series of companies ; High-speed ADC: TI, LT, AD ‘s high-speed (40MSPS ~ 80MSPS) 8?ADC series; High-precision ADC: TI, LT, AD ‘s high-speed (2MSPS ~ 40MSPS) 12/14 bit ADC series; High-speed DAC: AD, LT ‘s high-speed (40MSPS ~ 80MSPS) 8?DAC series; High-precision DAC: AD, LT ‘s high-speed (20MSPS ~ 80MSPS) 12/14 bit DAC series; 4, EX-USB FX2 main features of EZ-USB FX2 chip includes an 8051 processor , a serial interface engine (SIE), 1?USB transceiver , 8.5KB on-chip RAM, 4KB FIFO memory and a general programmable interface (GPIF), shown in Figure 2 Shown . 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 achieve specific functions , and to ensure its continuing high-performance transfer rates. FX2 also includes two general programmable interface (GPIF), allowing it to "No Adhesives , " and can connect to any ASIC or DSP , and it supports all common bus standards, including ATA, UTOPIA, EPP and PCMCIA. EZ-USB FX2 is fully applicable to USB2.0, backward compatible with USB1.1. FX2 are three kinds of packages : 56 feet SOPP, 100 feet TQFF ( thin quad flat package ), 128 feet of the TQFP. The difference between the number of input pins , the number of different output pins in order to address different application requirements. 5 , the system features: 1, a PGA ( programmable gain amplifier ), ADC with 20MSP ~ 40MSPS in high-speed 8-bit ADC, DAC with 20MSPS ~ 40MSPS High Speed 8-bit DAC. 2, SRAM with 128K × 8 high-speed SRAM. 3, 3, with 16 -channel digital input and 16 digital output channels can also be configured as a 32- channel digital output or 32 -channel digital input . 4 , prepared a USB2.0 device description document , so users familiar with the Cypress USB devices of various characteristics of the company . 5 , according to a variety of internal characteristics of USB2.0 devices , the preparation of the corresponding firmware code and the upper testing procedures. 6 , prepared USB2.0 transfer rate within the test program , a multimedia image display program as an example ( the images downloaded to the FX2 , the read back to host shows calculated display frames per second ) . 7 , will lead to USB2.0 ‘s Slave FIFO , users can connect to the user Slave FIFO channel board test . 8, supporting analog data acquisition and display software can be used as a more fully functional digital storage oscilloscopes . 6 Review : USB2.0 development system is a more general data acquisition and analysis system can be used as a portable high-performance (mainly for mobile systems) data acquisition card can be used as high-performance ADC, DAC device evaluation board , also can be used as a high-performance Portable virtual instrument to use , thanks to USB2.0 interface, can be overcome in the past to use the parallel port or USB1.1 interface, not portable real-time virtual instrument weakness .