Cypress AN2131QC Manuel du produit - Page 6

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Automatically Handles Low-Level USB Overhead

A USB hardware connection

is simpler than current

interface standards (ISA,

PCI, serial, parallel, and

SCSI). For example, there

are no IRQs or DMAs to set.

USB does not use direct

connections like RS232 or

EPP (Enhanced Parallel

Port). Instead, USB is a

packetized protocol similar

to telecommunication

standards such as X.25 or

frame relay. This makes

software development

complex.

EZ-USB Series 2100

The EZ-USB chip family reduces

the complexity of USB. It has a

predefined default descriptor

that causes it to function as a

generic USB device. Very little

code is required to operate the

EZ-USB chip when configured in

this default state. The default

descriptor can be replaced as the

peripheral manufacturer devel-

ops customized firmware.

Four Major Benefits of

Smart USB Core

The firmware code is

smaller and more

efficient than alternate

USB solutions. In the EZ-USB

family, the memory requirement

is reduced by a factor of two to

five times as compared to other

solutions. And, since less memory

is needed for firmware, board

size and system cost are reduced.

Efficient EZ-USB Code

Firmware

EZ-USB Family

File Type

Source

730 lines of C code

Binary

< 1 Kbyte

Test Code Supports:

USB Chapter 9

String descriptors

USB suspend/resume

Remote wake-up

Bulk endpoint loopback

USB firmware develop-

ment is faster since there

is less code to write. This

reduction in firmware allows the

design team to concentrate more

on software development for the

peripheral function.

Fewer 8051 MIPs are

dedicated to USB

processing. With the

EZ-USB family, as little as 10% of

8051 processing time is dedicated

to USB. That makes 90% of the

enhanced 8051 core's processing

time available for peripheral

functions. Alternate solutions

dedicate more of their micro-

controller bandwidth to USB

processing.

The EZ-USB family

handles most low-level

USB overhead automati-

cally. Therefore, the learning

curve to understand all the

nuances of USB is reduced,

yielding fewer code errors and

faster product development.

Alternate Solutions

5445 lines of assembly code

> 5 Kbytes