英文技术文章好难读哦

1.Introducing EZ-USB

1.1 Introduction
The Universal Serial Bus (USB) has gained wide acceptance as the connection method of choice for PC peripherals. Equally
successful in the Windows and Macintosh worlds, USB has delivered on its promises of easy attachment, an end to configuration
hassles, and true plug-and-play operation.
The latest generation of the USB specification, ’USB 2.0’, extends the original specification to include:
■ A new ’high speed’ 480 Mbits/sec signaling rate, a 40× improvement over USB 1.1’s ‘full- speed’ rate of 12 Mbits/sec.
■ Full backward and forward compatibility with USB 1.1 devices and cables.
■ A new hub architecture that can provide multiple 12 Mbits/sec downstream ports for USB 1.1 devices.
The Cypress Semiconductor EZ-USB® family offers single-chip USB 2.0 peripherals whose architecture has been designed
to accommodate the higher data rates offered by USB 2.0. The EZ-USB FX2LP device (CY7C68013A/14A/15A/16A) supports
both full speed and high speed modes. The EZ-USB FX1 device (CY7C64713/14) only supports the full speed mode.
The term ‘EZ-USB’ refers generically to both EZ-USB FX2LP and EZ-USB FX1 devices.
This introductory chapter begins with a brief USB tutorial to put USB and EZ-USB terminology into context. The remainder of
the chapter briefly outlines the EZ-USB architecture.
Note Please note this Technical Reference Manual does not cover the CY7C646xx or AN21xx products. Refer to the respective
Technical Reference Manual for these products for more information.

1.2 An Introduction to USB
Like a well-designed automobile or appliance, a USB peripheral’s outward simplicity hides internal complexity. There is a lot
going on ‘under the hood’ of a USB device.
■ A USB device can be plugged in anytime, even while the PC is turned on.
■ When the PC detects that a USB device has been plugged in, it automatically interrogates the device to learn its capabilities
and requirements. From this information, the PC automatically loads the device’s driver into the operating system.
When the device is unplugged, the operating system automatically logs it off and unloads its driver.
■ USB devices do not use DIP switches, jumpers, or configuration programs. There is never an IRQ, DMA, memory, or I/O
conflict with a USB device.
■ USB expansion hubs make the bus simultaneously available to dozens of devices.
■ USB is fast enough for printers, hard disk drives, CD-quality audio, and scanners.
■ USB supports three speeds:
❐ Low speed (1.5 Mbits/sec), suitable for mice, keyboards and joysticks.
❐ Full speed (12 Mbits/sec), for devices like modems, speakers and scanners.
❐ High speed (480 Mbits/sec), for devices like hard disk drives, CD-ROMs, video cameras, and high resolution scanners.
The Cypress Semiconductor EZ-USB family supports the high bandwidth offered by the USB 2.0 high speed mode. The EZUSB
chips provide a highly-integrated solution for a USB peripheral device. The EZ-USB chips offer the following features:
■ An integrated, high-performance CPU based on the industry-standard 8051 processor.
■ A soft (RAM-based) architecture that allows unlimited configuration and upgrades.