USB设备与PC间的通讯过程

USB设备与PC间的通讯过程
                                                                             Author: Jason.Qu

I Command (Get descriptor Who is out there?)
PC send the first frame:: Sync(01), SOF(A5),Frame#(DD), CRC5(15),EOP(01)

NOTE:

       Sync：Packet Start , signaling to the transceiver: “packet arriving”

       SOF: Start of Frame (every millisecond)

       Frame#: Frame number(0 - 2047) over rolling

       CRC5: 5 bit Checksum over Frame#

       EOP: End of Packet (D + and D- are low)

This is a command to request equipment (get descriptor add 0)

When usb is connected ,power on and trigger, PC will ask equipment(add 0),the usb equipment will return the descriptor

PC send the second frame: Sync(1),SETUP(B4),ADDR(0),ENDP(1),CRC5(8),EOP(1)

NOTE:

       SETUP: Setup Packet( start of control transfer)

       ADDR: Address 0 (default addr . f . every new plugged _ in dev.)

       ENDP: Endpoint 0(used for configuration)

PC send the third frame: Sync(1),DATA0(C3),DATA(as follows),CRC16(BB29),EOP(1)

NOTE:

       DATA :

       80: transfer direction,std.command

       06: get descriptor(get device descriptor generates an interrupt)

       00: index of descriptor

       01：device descriptor (function same the 06)

       00 00: language ID

       40 00: amount of bytes requested by host(little endian format; low byte first ,high byte least)

USB equipment responses the first frame that from PC: Sync(1),ACK(4B),EOP(1)

NOTE:

       ACK: Acknowledge Packet

Ii Every data transfer will be initiated with IN/OUT package by the host(PC)
PC send the first frame:: Sync(01), SOF(A5),Frame#(DE), CRC5(17),EOP(01)

PC send the second frame:Sync(1),IN(96),ADDR(0),ENDP(0),CRC5(8),EOP(1)

       IN: Data In Packet(Host requesting data from device)

USB equipment responses frame: Sync(1), DATA1(D2),DATA(as follows), CRC16(c8e7), EOP(1)

       DATA: first 8 bytes of the device descriptor initialized din fonfig.h

       12 : length of device descriptor

       01 : low – byte of USB – Specification

       00 : high – byte of USB – Specification

       00 : Device Class

       00 : Device Protocol

       00 : Device Sub Class

       08 : Max . packet size of endpoint 0

PC responses frame: Sync(1), ACK(48), EOP(1)

Iii End of Data Stage
PC send the first frame:: Sync(01), SOF(A5),Frame#(E0), CRC5(E),EOP(01)

PC send the second frame:Sync(1), OUT(87),ADDR(0), ENDP(0),CRC5（8），EOP(1)

       OUT: Data Out Packet(Host aborts data stage)

PC send the third frame: Sync(1),DATA1(D2),DATA(as follows), CRC16(0000), EOP(1)

       DATA: Empty data packet indicating data stage end

USB equipment responses frame that from PC: Sync(1),ACK(48),EOP(1)

Iv Reset from Host(10ms)
PC send RESET command to USB Device

RESET(12 81 60): Reset initiated from host

V Command Set Address(You are called Number 2 from now on!)
PC send the first frame: Sync(1),SOF(A5), Frame#(143), CRC5(4), EOP(1)

PC send the second frame: Sync(1), SETUP(B4), ADDR(0), ENDP(0),CRC5(8),EOP(1)

PC send the third frame: Sync(1), DATA1(C3),DATA(as follows), CRC16(D768), EOP(1)

       00: direction from host to device .std . command ,recipient device

       05: set address

       02: device address nr.2

       00 00 00 00 00 : default

       this command is handled by the C54x itself without extra software

USB responses frame: Sync(1), ACK(48), EOP(1)

Vi End of Data Stage
       PC send the first frame: Sync(1),SOF(A5), Frame#(144), CRC5(8), EOP(1)

PC send the second frame: Sync(1), IN(96),ADDR(0),ENDP(0),CRC5(8),EOP(1)

USB responses frame: Sync(1), DATA1(D2),DATA(as follows), CRC16(0000), EOP(1)

              DATA : Empty data packet from device handled by C54x Without Software

PC responses frame: Sync(1), ACK(48), EOP(1)

Vii Get Descriptor from Device Number 2(What are you like?)
       PC send the first frame: Sync(1),SOF(A5), Frame#(151), CRC5(1E), EOP(1)

PC send the second frame: Sync(1), SETUP(B4), ADDR(2), ENDP(0),CRC5(15),EOP(1)

PC send the third frame: Sync(1), DATA1(C3),DATA(as follows), CRC16(072F), EOP(1)

       80: transfer direction,std.command

       06: get descriptor(get device descriptor generates an interrupt)

       00: index of descriptor

       01：device descriptor

       00 00: language ID

       12 00: bytes to transfer

USB responses frame: Sync(1), ACK(48), EOP(1)

Viii IN request (get data about device description)
       PC send the first frame: Sync(1),SOF(A5), Frame#(152), CRC5(1C), EOP(1)

PC send the second frame: Sync(1), IN(96),ADDR(2),ENDP(0),CRC5(15),EOP(1)

USB responses frame: Sync(1), DATA1(D2),DATA(as follows), CRC16(C8E7), EOP(1)

              DATA :first 8 bytes of the device descriptor initialized in config.h

              12 : length of device descriptor

              01 : device descriptor type

              00 : low byte of USB – Specification

              01 : high byte of USB – Specification

              00 : device class

              00 : device Sub class

              00 : device protocol

              08 : Max . packet size of  endpoint0

PC responses frame: Sync(1), ACK(48), EOP(1)

Ix 2nd IN request (get data about device description)
PC send the first frame: Sync(1),SOF(A5), Frame#(153), CRC5(3), EOP(1)

PC send the second frame: Sync(1), IN(96),ADDR(2),ENDP(0),CRC5(15),EOP(1)

USB responses frame: Sync(1), DATA1(c3),DATA(as follows), CRC16(86db), EOP(1)

              DATA :first 8 bytes of the device descriptor initialized in config.h

              8B:low byte of vendor ID

              05:high byte of vendor ID(SIEMENS)

              41:low byte of product ID

              C5: high byte of product ID(C541)

              01: low byte of device number

              00: high byte of device number

              00: index for manufacturer string descriptor

              00: index for product string descriptor

PC responses frame: Sync(1), ACK(48), EOP(1)

X 3rd IN request (get remaining data is transferred)
PC send the first frame: Sync(1),SOF(A5), Frame#(154), CRC5(1D), EOP(1)

PC send the second frame: Sync(1), IN(96),ADDR(2),ENDP(0),CRC5(15),EOP(1)

USB responses frame: Sync(1), DATA1(D2),DATA(as follows), CRC16(FCF1), EOP(1)

       00: index for serial number string descriptor

       01: number of configurations

PC responses frame: Sync(1), ACK(48), EOP(1)

Xi Command: OUT transfer(with empty data) finishes the data stage
PC send the first frame: Sync(1),SOF(A5), Frame#(155), CRC5(1D), EOP(1)

PC send the second frame: Sync(1), OUT(87),ADDR(2), ENDP(0),CRC5（15），EOP(1)

PC send the third frame: Sync(1), DATA1(D2),DATA(empty), CRC16(0000), EOP(1)

USB responses frame: Sync(1), ACK(48), EOP(1)

XII Command : Get configuration Descriptor(How does the device function?)
PC send the first frame: Sync(1),SOF(A5), Frame#(157), CRC5(1F), EOP(1)

PC send the second frame: Sync(1), SETUP(B4), ADDR(2), ENDP(0),CRC5(15),EOP(1)

PC send the third frame: Sync(1), DATA1(C3),DATA(as follows), CRC16(9725), EOP(1)

              80: transfer direction , std . command

              06: get descriptor

              00: index of descriptor

              02: configuration descriptor

              00 00: language ID

              FF: low byte of bytes to transfer

              00: high byte of bytes to transfer

USB responses frame: Sync(1), ACK(48), EOP(1)

Xiii In Request : Gives Feedback to How does the device function?
PC send the first frame: Sync(1),SOF(A5), Frame#(158), CRC5(F), EOP(1)

PC send the second frame: Sync(1), IN(96),ADDR(2),ENDP(0),CRC5(15),EOP(1)

PC send the third frame: Sync(1), DATA1(D2),DATA(as follows), CRC16(5020), EOP(1)

              DATA: first 8 bytes of the device descriptor initialized in config .h

              09: length of configuration descriptor

              02: configuration descriptor type

              19 00: length of configuration , interface and endpoint descriptor

              01: number of used interfaces in this configuration

              01: value to set this configuration with Set Configuration

              00: index to configuration string descriptor

              60: attributes of configuration

USB responses frame: Sync(1), ACK(48), EOP(1)

Xiv 2nd In Request : Gives Feedback to How does the device function?
PC send the first frame: Sync(1),SOF(A5), Frame#(158), CRC5(F), EOP(1)

PC send the second frame: Sync(1), IN(96),ADDR(2),ENDP(0),CRC5(15),EOP(1)

USB responses frame: Sync(1), DATA1(C3),DATA(as follows), CRC16(273E), EOP(1)

              DATA: next 8 bytes of the device descriptor initialized in config .h

              32: max . power consumption (in 2mA units)

              09: length of interface descriptor

              04: interface descriptor type

              00: number of interfaces

              00: alternate settings

              01: used endpoints used in this interface

              00: interface class

              00: interface sub class

PC responses frame: Sync(1), ACK(48), EOP(1)

Xv 3rd In Request: Gives Feedback to How does the device function ?,details
PC send the first frame: Sync(1),SOF(A5), Frame#(15B), CRC5(D), EOP(1)

PC send the second frame: Sync(1), IN(96),ADDR(2),ENDP(0),CRC5(15),EOP(1)

USB responses frame: Sync(1), DATA1(C3),DATA(00), CRC16(0000), EOP(1)

              DATA: 00 :　polling interval for interrupt endpoints

PC responses frame: Sync(1), ACK(48), EOP(1)

Xvi Command: OUT transfer finishes the data stage
PC send the first frame: Sync(1),SOF(A5), Frame#(15B), CRC5(D), EOP(1)

PC send the second frame: Sync(1), OUT(87),ADDR(2), ENDP(0),CRC5（15），EOP(1)

PC send the third frame: Sync(1), DATA1(D2),DATA(empty), CRC16(0000), EOP(1)

USB responses frame: Sync(1), ACK(48), EOP(1)