Handheld TFTP Server with USB Andrew Pangborn Michael Nusinov RIT Computer Engineering – CE Design 03/20/2008

Outline Project Description Mass Storage Functionality TFTP Server Functionality User Interface Description Project Requirements Platform Overview and Board Discussion USB Gadget Interface Implementation Difficulties Systems Testing Questions

Problem Description GE has radio towers that require firmware updates. Install updates by downloading specifically named files from a TFTP server Don’t currently have a convenient way of deploying updates to devices in the field. They want a compact device that can deploy updates to the radio towers on-site.

Solution Develop a handheld device with an Ethernet port that hosts a TFTP server. Our handheld device also contains USB and acts as a Mass Storage device when plugged into a PC.  Allows updates to be easily loaded onto the device

Mass Storage Aspect The handheld device is connected to a normal PC through a USB connection It appears to the PC as a mass storage device (like a thumb drive or external hard drive) Files can then be transferred to or from the device

TFTP Aspect TFTP is a simplified version of FTP providing basic GET and SEND functionality GET commands are sent from the radio and received by the handheld device. The handheld device then transfers the required file (or files) to the radio

Step 1: Load Firmware onto device from PC via USB USB Step 2: Travel to on-site location Step 3: Tower hardware downloads firmware file via wired Ethernet and TFTP Ethernet

User Interface Reset Button ON LED indicator Ethernet Status “Complete Status” LED+Speaker  Indicates that a TFTP transfer has finished with LED and small speaker On/Off switch

Project Requirements Storage Capacity:  ~8MB for base Linux system + kernel,  2-3MB per firmware image Size - Small enough for an operator to easily transport to radios USB and Ethernet Support Batteries  Common batteries that are easy to replace

Platform Overview ARM920T Processor  Low Power, Small form-factor  Capable of running an operating system like Linux for Ethernet/USB support as well as an FTP server application  USB Device and Host Controller embedded in processor NAND Flash Memory (file system)  Non-volatile  ARM9 processors contain support for boot-loading from Flash SDRAM (system memory)  Memory controller for SDRAM included inside ARM9 as well Linux

Basic System Architecture General Purpose Processor Volatile SDRAM used by operating system Non-Volatile Flash memory used for boot image and file storage Processor interfaces with USB and Ethernet Arrows Indicate direction of file transfers

Samsung S3C2410X Processor

Samsung S3C2410X Dev Board ARM920T based Processor 32MB SDRAM 64MB NAND Flash USB Host and Device Ports RS /100 Ethernet LEDs and General Purpose Digital I/O pins

USB Host vs USB Device Majority of computers only have Host Controllers Devices such as PDAs and thumb drives have a Device controller The S3C2410X (along with many other ARM boards) contain both host and device controllers The PC’s Host controller initiates communication with the device controller on the board to access the flash storage

USB Gadget API USB Gadget API provides a framework for developing USB applications The File-backed Storage Gadget uses the Gadget API to mimic a USB Mass Storage Device The Mass Storage gadget is a software layer on the embedded device that provides the host PC with sector-based access to a portion of the Flash storage

Implementation Difficulties Getting Linux to act as a USB Slave device Interfacing user-land application (the TFTP server) with the general purpose I/O pins of the processor (LED and Speaker)

Testing Strategy Functional Testing  USB Enumerates on PC as mass storage device Files can be copied to/from the device, files can be deleted. Confirm these operations by looking at the device’s file system via serial terminal and Linux commands.  FTP Download a file from the device using a TFTP client and a laptop Performance Testing  Transfer Speeds Copying files to/from the device with USB and FTP  Battery Life  Robustness Power failures / interrupted transfers don’t corrupt the system

Questions? Comments?