Implementation of a USB Slave to Slave File Transfer Device Using
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1. Button Press User input command Path File System Controller USB Flash Drive USB Flash Access Commands Drive Source Notification NRZI and Serially USB Controller Encoded Packets ISB Flash Drive Destination Figure 2 General Block Diagram lof Request Il USB SLAVE TO SLAVE FILE TRANSFER DEVICE The USB Slave to Slave File Transfer Device is a device that facilitates file and folder directory transfers from one flash drive to another flash drive using the USB 1 1 interface without the need for a Personal Computer PC to act as mediator Figure 1 shows the system setup while figure 2 shows the general block diagram of the system The system allows the user to select files or folders directories for copying from a source flash drive to a user selectable directory in the destination flash drive The device also supports a copy all function which works the same way Contents of the flash drives are displayed in their 8 3 filename format thru a twenty character by four lines sized dot matrix character liquid crystal display LCD The system is also able to check for identical file folder directory names and requests for a user confirmation to either proceed and overwrite a file folder directory or not In addition the system is able to check if there is sufficient memory space for the file folder directory to be copied onto the destination flash drive if not the system requests the user to del2. EZ Host Programmable Embedded USB Host Peripheral Controller Specifications Cypress Semiconductor Corporation California 2004 8 Cypress Semiconductor Corporation Framework User s Guide For the CY4640 Reference Design Kit Cypress Semiconductor Corporation 2004 9 Cypress Semiconductor Corporation CY4640 EZ Host USB MSC Reference Design 1 0 Cypress Semiconductor Corporation California California September 17 2004 10 USBFlashDrive org site USB Flash Drives USB Memory and Portable Computer Hard Drive Information online Available http www usbflashdrive org usbfd_overview html July 1 2005
3. FAT 32 FAT16 or FAT12 A large portion of this submodule is already implemented by the frameworks included with the Cypress CY4640 Reference Design Kit Error Reference source not found However some low level functions required additional SCSI commands to read some sectors of the FAT formatted memory device C USB Controller Module The USB Controller module is responsible for starting up the system handling the packets computation and checking of error checking bits packet encoding conversion of packets from parallel to serial and vice versa and NRZI decoding and encoding This module accepts the commands to either read or write onto a USB flash drive as requested by the File System Controller Module Input from the USB flash drives is the result of an earlier request for data These requests include content information i e file names actual content i e files or identification signals i e the connected USB device is checked if it falls under the Mass Storage Class MSC or Human Interface Device HID Block diagram is shown in figure 8 1 2 The module also governs the data that needs to be transmitted to the USB Flash Drives as well as process and send the results of the transaction to the File System Controller Module In addition the module also sends notifications to alert the user of the status of the system or the operation i e the status of a copy or delete command USB Host Controller The USB Host Contro
4. 20 character by 4 lines LCD and a microcontroller solely for controlling the LCD and receiving user input Navigation The Navigation submodule is the input handling hardware of the system This submodule includes six input buttons and circuitry for filtering the input signals The Navigation submodule sends a corresponding signal for each button press to the microcontroller that controls the LCD so that it could update the screen and or send commands to the File System Controller module for processing i e opening a folder and initiate a copy command Figure 5 shows the button layout of the Navigation submodule Function Label ee LKOUOUDUUeEIRIe INSIDE lal Vertical Scroll a Control Buttons f Horizontal Scroll 80 Figure 5 Button Layout Screen Display Formatter The Screen Display Formatter submodule is responsible for arranging and ordering the contents of the LCD screen It formats the screen to display the appropriate option menus folder contents path names content type folder or file The Screen Display Formatter submodule is the software part of the User Interface module It receives the names of the files and folders to be displayed from the File System Controller module Figure 6 shows how the screen is formatted lt Path of the Current Directory gt lt First Content gt lt Second Content gt lt Mode gt lt First Command gt lt Second Command gt Figure 6 Screen Format B File Sys
5. Capacities Source Device Destination Device Average Speed PQI 256 MB PQI 512 MB PQI 256 MB 531 636 Kbps 182 263 Kbps PQI 512 MB 533 972 Kbps Table 10 Folder Transfer Test Summary for USB Flash Drives with Different Brands and Same Capacities Destination Device Average Speed Source Device Transcend 512 MB PQI 512 MB Transcend 512 MB PQI 512 MB 144 348 Kbps D File Accuracy A transfer transaction is considered successful if for single file copy the file has been copied completely For folder copy all the contents within the folder directory concerned are copied completely this includes sub folders and files within the folders to be copied This test utilizes the files obtained from the Transfer Speed test where they are compared to the original files using the Message Digest Algorithm 5 MD5 The MD5 results of the original files are compared to the MD5 of the copied files to verify the integrity of the written data In total each test file and folder is transferred 33 times The accuracy percentage is taken using the ratio of the number of successfully transferred files and the total number of files Table 11 shows that files and folders transferred are 100 accurate It is also worthwhile to note that when the folder transferred is beyond the six level depth limit the files and folders beyond the said limit are not copied and would generally lead to a low accuracy percentage Another cause for inacc
6. PQI Transcend 16 MB 256 MB 512 MB Source Device Kbps Kbps 195 208 143 519 Sa ea Transcend 512 197 529 515 102 paneer eared ae 2 2 Device recognition Table 1 shows the brand model and capacity of the USB flash drives used while table 2 shows the test files Table 4 Single File Transfer Test Summary for USB Flash Drives with used Different Brands and Same capacities Ill Performance Test Threee tests are used to asses the performance of the system speed of the file transfers accuracy of the copied files and USB A Transfer Speed Destination Device Average Speed Transcend 512 MB PQI 512 MB 184 701 Kbps 142 862 Kbps C Folder Copy Test Source Device Transcend 512 MB PQI 512 MB The results from the transfer speed test show that the speed of the destination device is constant for all pairs of USB flash disks The file transfer speed to the generic 16MB flash disk averages at 199 186Kbps the 256 MB PQI at 558 191 Kbps the 512MB PQI at 171 376 Kbps and the 512MB Transcend at 144 548Kbps Overall the 256MB PQI flash drive achieved the fastest speed of 609 977Kbps paired with the generic 16MB flash drive as the source for single file Table 3 shows the result of this test The Folder Copy Test involves five folders containing various combinations of files and sub directories The sizes of the folders range from 53 900 bytes to 11 687 141 bytes The folders have 17 to 91 files with folder depths ranging
7. Implementation of a USB Slave to Slave File Transfer Device Using Microcontrollers Mark Alvin U Chua Charles D Jorge Ana Marian M Pedro Brian Emmanuel G Tam Gregory G Cu College of Computer Studies De La Salle University Manila 2401 Taft Ave Manila Abstract The popularity of Universal Serial Bus USB storage devices is an indication of the computer user s need for a fast large capacity and easily accessible system for data storage The disadvantage of USB storage devices is that being a peripheral device it needs a host usually a Personal Computer PC to initiate and mediate communications between two USB storage devices The USB based slave to slave file transfer system seeks to create a bridge between two slave devices for file transfer when a computer is unavailable The USB Slave to Slave File Transfer System USS FiTraDev utilizes the Cypress CY76C7300 USB controller to facilitate file transfers while a PIC18F458 microcontroller handles the user interface The user interface consists of four scroll buttons two multifunction control buttons and a 20x4 line LCD screen The USS FitraDev system supports USB flash drives that operate under the USB Mass Storage Class Copy functions include single file transfer single folder transfer and entire memory content transfer The system allows overwriting when a file of the same name is found in the destination flash drive An auto rename function is also available should the user c
8. ete some files or folder directories to free some memory in the destination flash drive The user may or may not opt to delete anything A User Interface Controller Module This module is responsible for obtaining user input and displaying user requested information thru an LCD It consists of three submodules namely the LCD Controller Navigation and Screen Display Formatter as shown in figure 3 Formatted Character Representation Valueg Controller oe Submodule Submodule User input Screen Filename Navigation command Conten Characters Button Press Submodule Path LFN File System Controller Figure 4 User Interface Controller Block Diagram User input is received thru this module however only two out of the six buttons are interpreted and executed within the User Interface Module These buttons are the Left and Right navigation buttons whose function are to scroll through the displayed path or Long File Name LFN format of a file or directory The input from the Up and Down navigation buttons and Command Buttons 1 and 2 are converted to their corresponding command codes and are forwarded to the File System Controller module for execution All information to be displayed is received from the File System Controller module LCD Controller The LCD Controller submodule is the hardware that interfaces the LCD to the main hardware system It is composed of a
9. from 1 to 5 Table 7 shows Table 1 USB Flash Drives Used Year a the test folder and its properties Table 7 Folder Copy Test Test Folders of of 3 LitFileDeep oLvi s 17 7 7121 893 17 92 7 2 1 8 2 S 256 MB ool Drive U339S 2006 512 MB Cool Drive U339S 2006 JetFlash Table 2 Test Files s e TotalMix 6lvi_ 6 f 9 MultiFolder 2 2 sif 1 3 2 gt 38 22 2 3 508 969 5123 6 4 447 965 o0 123 Folder Descriptions 1 011 1 LitFileDeep 6 Lvl a mixture of small medium and large files Reflection Paper doc 28 672 in a partially complex folder structure HP_App doc 256 000 2 SimpleManyLargeFiles Single level folder structure having medium sized files CIMG0478 JPG 999 424 3 TotalMix 6lvl a mixture of small medium and large files in a KH2 Intro mp3 4 912 691 complex folder structure in 6 levels ore 4 MultiFolder 2 2 level structure with multiple folders inside CnC Tiberium mpg 13 287 428 containing either no files large files small files medium sized files or mix 5 MultiASmall Lvll 1 level folder that has several very small files lt 2 5 KB 6 MixLargeSmall 2Lvl Mixture of large small and medium size files in a 2 level folder structure B Single File Copy Test The file copy test involves six files with sizes ranging from 1 011 bytes to 13 287 428 bytes 12 6 MB For each pair of flash drive
10. hoose to retain the file The delete function is enabled when the size of the file to be transferred exceeds the available space on the destination flash drive The system has a file transfer accuracy of 100 for single files and folders that are within the six folder depth level with a file transfer speed of 609 997Kbps The use of five AA sized alkaline batteries allows the transfer of up to 730MB of data in a span of 6 hours and 34 minutes using a linear regulator circuit I INTRODUCTION As the development of USB enabled peripherals increases the Universal Serial Bus USB has rapidly become a de facto standard in communication with the Personal Computer PC and has lead to new technologies for interfacing memory devices These memory storage devices connect to the USB ports and appear as removable storage device in personal computers the most popular of which is the USB Flash Drive The disadvantage of using USB Flash Drives is that it requires a PC to initiate file transfers between one another 10 As a solution to the USB Flash Drive disadvantage the research project aims to develop a device that allows file transfers between two USB memory devices without the need for a Personal Computer PC This paper discusses the current implementation of all three modules as well as the testing process and partial results from file transfer speed tests between USB Flash Drives of different brands and capacities Figure 1 System Set up
11. hout error checking bits Packets with error checking bits removed Error Bit Handling Submodule Serial Handshake serial format Serial Packets with Error Checking Bits serial format NRZI and Serially USB Host Controller Encoded Packets Submodule Received Serial Raw data Packet USB Flash Drive Source USB Flash Drive Destination Figure 8 USB Controller Module Flowchart Error Bit Handling The Error Bit Handling Submodule is responsible for adding error checking bits to the data about to be sent Furthermore the submodule also checks the received packets from the sender flash drive for corrupted data The submodule forwards an acknowledgement ACK handshake in return if the received packet does not contain any errors Start Up The Start up submodule handles the system start up It deals with the detection of the USB devices attached to the system The Table 3 Single File Transfer Test for USB Flash Drives with Different Brands and Capacities submodule checks the USB ports for USB devices and their properties For the system to start up properly there must be 1 two USB devices attached 2 the USB devices must fall under the Mass Storage Class MSC device class and 3 under the Solid State device subclass and 4 it must use the FAT 12 16 32 file system If any of the conditions fail other that the 2 USB device Destination Device Average Speed Generic
12. ller submodule is the main hardware used by both the USB Controller Module and the File System Controller Module The submodule physically interfaces with the USB flash drives and is responsible for converting raw data and information to their proper NRZI encoding as specified by the USB technical specifications Furthermore the submodule is capable of encoding or decoding the incoming NRZI data from the USB flash drives and forwards it to their respective submodules for further processing The system uses the Cypress CY7C67300 a programmable microcontroller and USB multi role embedded _host peripheral controller which has its own Basic Input Output System and Framework program Most of the software submodules make use of the available framework where the functions are already abstracted and simply need to be enabled and customized depending on the application 6 Packet Handler The Packet Handler submodule handles all packet generation and interpretation The submodule generates packets without error checking bits which will be used as either data or command packets depending on the command sent by the File System Controller Module Requests are interpreted and the error free results and status notifications are sent as output File System Controller USB Flash Drive Result of Notification Start up Access Commands Request Submodule Request Device Information Packet Handler Submodule USB Device Information Packets wit
13. rst two contents of the current directory The last line contains the function labels for the Left and Right Control buttons The hardware interface consists of the Up and Down Navigation buttons which are used to browse the contents of a directory the Left and Right Navigation buttons for scrolling through the path name and two control buttons to execute functions displayed on the screen V REFERENCES 1 D Anderson D Dzatko Universal Serial Bus System Architecture MindShare Inc 2001 2 J Axelson USB COMPLETE Second Edition Madison WI Lakeview Research LLC 2004 3 ypress Semiconductor Co EZ Host Mass Storage Reference Design online Available http www cypress com portal server pt space Community Page amp parentname CommunityPage amp in_hi_userid 2 amp control SetCo mmunity amp CommunityID 209 amp PageID 418 amp r_folder Referen ce 20Designs amp r_title EZHost 20Mass 20Storage 20Refere nce 20Design June 24 2005 4 Cypress Semiconductor Corporation OTG BIOS User Manual Version 1 2 Cypress Semiconductor Corporation California 2003 5 Cypress Semiconductor Corporation CY4640 Hardware User Manual Version 1 1 Cypress Semiconductor Corporation California 2004 6 Cypress Semiconductor Corporation Framework User s Guide For the CY4640 Mass Storage Reference Design Kit Cypress Semiconductor Corporation California 2004 7 Cypress Semiconductor Corporation
14. s all six files are copied and timed for three trials from which the average time is taken Table 2 shows files and its size being Large files are categorized as files over 1024 KB while Medium tratisterred files are between 20 KB and 1024 KB in size and Small files fall Table 4 lists the average speed at which the files were transferred The average speed was calculated by dividing the size of the file to be transferred by the average time of three trials below 20 KB The recorded file sizes are based on the file s actual size and not on the amount of memory space they take up on disk The Folder depth is counted starting from the subdirectory of the folder directory concerned Figure 9 illustrates how the folder depth is determined B Ga VeryDeepmsssssseess Root Level O me E First Level B id D ovvemese Second Level js Figure 9 Folder Depth Numbering VeryDeep is the name of the folder to be transferred Note that the Root Level Folder in this case the VeryDeep folder directory is not counted as one level The summary of the test results are found in table 8 table 9 and table 10 Table 8 Folder Transfer Test Summary for USB Flash Drives with Different Brands and Capacities Destination Device Average Speed Source Deyici Generic PQI Transcend 16 MB 256 MB 512 MB 571 171 204 821 Transcend 207 615 547 898 512 MB Kbps Kbps Table 9 Folder Transfer Test Summary for USB Flash Drives with Different
15. s for debugging with the PC s HyperTerminal The USB Host Peripheral Controller requires a 12MHz clock source from which an internal Phase lock Loop PLL produces a 483MHz internal clock The same software used with the Cypress RDK is able to run on the prototype board Test results verify that the maximum transfer speed of the prototype is 609 977Kbps shown in table 3 Both speeds are taken from the Single File transfer test between the 16MB generic Flash disk as source device and the 256MB PQI Flash disk as the destination It is observed however that the speed of the destination USB flash drive is an important factor for fast data transfer the source flash drive speed is irrelevant Similar results are seen with same capacity and same brand flash drive transfers The delete and overwrite functions proved successful during software development and testing phase of the study no recorded tests are made for this function The system is able to operate successfully using batteries The most cost effective approach is the use of five alkaline AA sized batteries which are able to transfer 730MB of data in a span of 6 hours and 34 minutes The user interface system is designed to allow the user to browse and choose specific files or folders to transfer between the source and destination devices The screen consists of only the important data to avoid cluttering the screen The scrollable path name is shown on the first line followed by the fi
16. tem Controller Module The File System Controller is responsible for all file management processes and FAT file system access for the system It mediates between the display user interface and USB communications module A large percentage of the system s software is found in this module since it contains most of the system s core functions Figure 7 shows the block diagram The major commands handled by the submodule include the up and down navigation buttons and the different functions attributed to command button 1 and 2 i e copy delete browsing thru files folders and the back command File Manager The File Manager Submodule is responsible for all file management functions features that are available in the system These features include copying a file or folder overwrite rename delete and browsing of the source and destination flash drive User Interface Controller User input command Filename Path Characters LFN Screen Content File Manager Submodule Controller Notification Suis USB Flash Drive Access Commands Result of Request USB Controller Figure 7 File System Controller Block Diagram FAT32 16 12 Controller The FAT32 16 12 Controller mediates between the File Manager submodule and the USB Controller Module It is responsible for abstracting the File System so that the File Manager submodule could easily access the File System be it a
17. urate file transfers would be that the prototype board is malfunctioning and may need to be restarted or serviced Table 11 File Accuracy Test Results A Accuracy Filename zZ Single File Transfers D9324F3FA083452F 04C5SCAABABF26681 COD07E2C71C2F9CE 1CB3DC3D782FD927 4856547D0F70C6D3 C91E2FF162F7834D ADB0379FB28E36A6 ABDOD6COBCA0681F 605195ED403842DD A10CFF5A41D1B4B5 64A70C3DEDB53345 9COB9D6954B6C3CB STANDA 1 TXT 100 REFLEC 1 DOC 100 HP_APP DOC 199 CIMG0478 JPG 100 KH2INT 1 MP3 100 CNC TI 1 MPG 100 Folder Transfers LitFileDeep 6Lv1 SimpleManyLargeFile TotalMix 6lv1 MultiFolder 2 MultiASmall Lv11 MixLargeSmall 2Lv1 o o o Note Folder transfer does not show any MD5 values because each file has its own MDS value IV CONCLUSION The design of the microcontroller system is based on the simplified schematic of the CY4640 Mass Storage Reference Design Kit RDK which uses the Cypress CY7C67300 USB Host Peripheral Controller The external Serial EEPROM initially holds the user s program before it is loaded to the USB Host Peripheral chip Since only 15K bytes of the USB Host Peripheral Controller s internal memory is allocated for the user s program and data it is not sufficient to hold the working program of the prototype An external SRAM was included in the design to compensate for the lack of internal memory The RS232 Transceiver is required by the LCD Module as well a
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