Development Of USB_Host Based On FS44BOX And CH375A

With the development of progress along with the living numeral of mankind,the data gather system just walk up us from the professional applied realm,thepersonal computers, PDA, digital camera, multi-function mobile phone,MP3,MP4,the recording pen etc. are all the incarnations that the data gathersystem。While we observe these products carefully, we find they all have thecommon characteristics: support the USB protocol。USB,means Universal SerialBus。So, whether our data gather system of the past can adopt theUSB to carry out or not? The specification of USB provides thehigh-speed data transport, and the media it saves to is the U disk and ambulationhard drives which is more and more big。 If we carry on data gather with MCU ,and use the U disk to save data, our data gather system only need to carry out thedifferent data gather function, the data saving part then can use the general USBmodule。According to the above viewpoint, we carried on the theories to study andpractice, and carried on the summary.Our main mission is to carry out the USB host,which having such requests asfollowing :1,The CPU of this host should be able to attains the requests of the data gathersystem to gather data;2,This host mainly carries on reading and writing to the U disk;3,The operation of Reading and writing to the U disk should be able to beidentified by the essential operate system.According to the above requests, we distinguished to study themicroprocessor of ARM, host of USB and FAT document system.ARM( the Advanced RISC Machines), can be thought as not only a name ofcompany,but also a general name of the microprocessor,or a name of thetechnique。The ARM has the following characteristics:The small and low power ofphysical volume consume, low cost,high performance;Supports the Thumb(16)and ARM(32) instruction set,the ability is compatible with 8_bit and 16_bitmachine pieces;A great deal of usage register, the instruction was performancedfaster;Most data operations are completed in registers;the method of Addressingis simple and agility,carry out efficient;The instruction length is fixed。So far,the microprocessor and technical applications of ARM almost have alreadygone deep into the each realm:The industry control, wireless communicationrealm,network apply,consumed electronics product and becomes to be like andsafe product;and it is go foreword to more realm 。Because the ARM applicationextends continuously, the product is quick to increase,and cost becomes lowercontinuously,at the time of this topic's choosing processor, we abandon traditional51 series, deciding to make use of this opportunity to approach the ARM,understanding the ARM。The USB host system is unique in the whole USB system, it includes asfollows 3 layers:The USB Bus;the USB System;USB Client 。Among them,the USB Bus manage the electricity and the protocol layer interlink age。The USBSystem uses the host controller to manage the data transport between the host andequipments 。What the Client describe is the software package which is needed tocommunicate with equipments of USB directly。The main function that the USB host complete includes 5 aspects as thefollowing:Examines the conjunction and the disconnect of the equipments ofUSB;Manages standard control piping between host and equipments;Managesthe data flow between host and equipments;Collects the statuses of theequipments,statistics the activity of the USB Bus;Control and Manage the electricinterface between the host controllers and the equipments, include providingcertain current for the endpoint。In order to carry out an USB host system, we need to choose a hostcontrol chip still。We chose the chip of CH375A, it has the following maincharacteristics:1, The full speed USB-HOST connects, and permit the USBV2.0, the machine of outer circle piece needs the crystal and capacity only。2, Thehost endpoint carries each 64 bytes for input and output buffer,supporting the 12Mbps full speed USB equipments。3,Support the USB control transport , thebulk transport,the interrupt transport 。4, Examine the conjunction and thedisconnection of the USB equipments automatically,the affairs circular thatprovides the equipments connection and disconnection。5,Place the processor thatprovides the protocol of control transport inside, simplify the in common usecontrol transport。6,Inside place the firmware processing mass storagecommunication agreement of the saving equipments, support the savingequipments of the USB that the Bulk-Only transport protocol and SCSI, UFI,RBCs or other USB hard drive used the equivalent command set( include the USBhard drive/ USB flash disk/ U disk)。7, Support the 5 V power supply electricvoltage and the 3.3 V power supply electric voltages, and support low powerconsume mode。The FAT document system is a more popular file system currently。It takes"cluster" as the unit on the hard drive to assign space for file。The FAT is themeaning that File Allocation Table , its contents is the current usage of each clusteron the patition。According to the bit's number to describe the order of cluster,thereare several category types of FAT12, FAT16, FAT32。When the length of thefile is smaller than a cluster , using a cluster's space to the saving the file;Whereas more clusters would be used;and means out this several clusters with theform of the chain of cluster in the FAT, the contents of the each cluster is no usedmarking or the file end marking or the number of next cluster。There is a FDTbehind in the FAT,where saves all the files' name and the beginning clusternumber。If you want to operate the files,you must operate the FDT。Theinformation of the FAT and the FDT can acquire from the MBR of the disk and theDBR of the partition。According to the 3 parts theories,we carried on the design of the hardwareof the system。If we develop the system based on the microprocessor of ARM,we need to design the outer circuit of the ARM first, and to purchase the expensiveARM emulator。To shorten the development period,lower the developmentexpenses, we choose the usage more mature FS44B0X ARM developmentboard, which carry out the common outer circuit of S3C44B0X,and can debugonline,and give all the feet of the S3C44B0X with the form of the plug。Thus, weconnect the footprint on the circuit board we designed ourself with the feet of theS3C44B0X by the electric outlet,and weld CH375A and its outer circle chipsaccording to the request of the 3.3 V electric voltage work mode 。And, weswitch the power supply that the development board used to the 9 V,2 W,andfrom the development board last the derivation 5 V and the 3.3 V electric voltages。Now the power supplies the development board, the CH375A and the equipmentsof USB at the same time.The system software design begins with the CH375A chip initialization 。Successful the beginning starts to turn, we set the CH375A's work mode, waitingfor the conjunction of the U disk。After examining the U disk conjunction, wemake use of the CH375A's read command to read the MBR sector on the U disk,acquire the information of the FAT, FDT of this equipments。And according tothe format of the FAT file system,we design and carry out on the file operation ofestablishing, modifying, deleting on the U disk。After the designation of the software and hardware and debugging,we havealready carry out a simple USB host modular,which based on the FS44B0Xdevelopped board and make use of the chip of CH375A。 The moldular supportsto the U disk and the portable hard drive to read and write now。Next ,we shouldstrengthen the stability and the compatibility of the modulat, and test its function byconnecting to a part of a data gather system。...