Shared Memory IP Simulation

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Shared Memory IP Simulation

• Ben Davis

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Outline

• Description
• Target Hardware
• Simulation Model
• TCP/IP
• uIP
• lwIP
• Results

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Project Descritpion

• OS Independent TCP/IP Implementation
• Project requirments defined by employer, Applied
  Reasearch Laboratories
• Hardware is still in development phase
• Start of software development early
• Simulate a shared memory interface to a TCP/IP
  stack
• Run simulation on linux, with minimal OS
  dependencies
• Utilize uIP or lwIP tcp/ip stack
•  

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Hardware, microcontroller

• Atmel SAM3U4E
• ARM Coretex M3 revision 2, up to 96MHz
• Memory protection Unit
• Thumb-2 Instruction Set
• Embedded Flash (64-256Kbytes)
• Embedded SRAM (16-48Kbytes)
•  

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Hardware, MAC

• Altera FPGA, Cyclone II
• Triple Speed Ethernet Megacore Function
• 10/100/1000-Mbps media access controller (MAC)
• Flexible IP options - MAC only, MAC.....

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Hardware
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Software Emulation

• MicroController
• Primary focus is the running of TCP/IP, this can
  be run in a linux environment with minimal OS
  oriented function calls
• Network driver accessing OS shared memory instead
  of static shared memory
• MAC
• Secondary Application running in linux access
  same shared memory space as uIP
• Utilize tunneling driver (/dev/net/tun) to create
  virtual point-to-point network
• Actual application will have a translator in the
  FPGA to convert the shared memory access to
  avalon interface. 

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TCP/IP Model

• FTP, SSH, TELNET, ...
• TCP,UDP,...
• IP(v4, v6), ICMP,...
• Tunnels, PPP, MAC,...

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uIP

• "The open-source uIP TCP/IP stack provides TCP/IP
  connectivity to tiny embedded 8-bit
  microcontrollers, with maintained
  interoperability and RFC standards compliance."
•  
• http//www.sics.se/adam/uip/index.php/Main_Page
• Adam Dunkels 
•  
• Very small code size
• Very low RAM usage, configuarble at compile time
• Numerous ports available

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uIP, Porting

• Network device
• init()      request shared memory
• read()    read from shared memory
• write()   write to shared memory
• Timer
• clock_init()
• clock_time()    gettimeofday()
•  
• uipopt.h
•  
• 32 bit addition, crc32

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lwIP

• More Advanced
• Fully Functional
• thread support
• semaphore and mailbox allocation 
• Core Functionality
• single threaded model
• preferred No-OS option 

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lwIP, Porting

• Only Core Functionality
•  
• Network device
• init()      request shared memory
• low level input()    read from shared memory
• low level output()   write to shared memory
•  
• Polling or asynchrounous

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TCP/IP Application

• httpd webserver
• Bidirectional test application 
• access through mozilla, navigate web interface
• wget for course output performance

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SAM3U4E

• Beyond Simluation
• Toolchain for SAM3U4E
• Codesourcery g lite eabi
• armv7 thumb2 library
• Porting
• initialize system resources
• new timer calls

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Results/Tradeoffs

• uIP vs lwIP
• space - uIP
• throughput- lwIP
•  
• Could utilize a minimalist OS like eCOS, which
  inlcludes lwIP, or freeRTOS.
• Validity of simulation.
•  

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Conlcusion

•  
•  
• Questions?