Team Market A Synthesis of Catastrophe Final Class Presentation

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Team MarketA Synthesis of Catastrophe Final
Class Presentation
Kermin Fleming Ka Wing Ho Jonathan Wilson Naju
Mancheril
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• In the beginning was the plan,and then the
  specificationAnd the plan was without form,and
  the specification was void.
• --Dictionary.com snafu principle

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Review of Design Goals

• Original Design Goals
• Support LCD display interface X
• Decided LCD Display was redundant by DR2
• Dangerous virus voice warning v
• Cope with garbled/distorted signals ?
• Advanced Signal Processing found to be too
  ambitious by DR2. Testing still pending.
• Final Design
• Voice warning is implemented
• Added Features Voice Identification of ALL
  viruses name, not just dangerous ones.

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Changes in architecture

• No More SRAM
• Original idea store decoded audio data
• Problem reads from SRAM and subsequent
  asynchronous transmission too slow for real-time
  play back
• Solution 1 Need 64KB. DSP has 32KB, ARM has
  32KB. Store ½ of the processed data on DSP and
  put the rest on ARM
• Real-time audio playback works but

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Changes in architecture cont

• No More SRAM
• Original idea store decoded audio data
• Problem Dealing with file halves is hard to
  manage, system is difficult to debug, more
  interconnections.
• Solution 2 Need 64KB. NIOS has 100KB. Use NIOS
  to buffer decoded audio file.
• Real-time audio playback works.

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Changes in architecture cont

• No multiple custom cores
• Original Idea multiple parallel cores connected.
• Problem arbitration difficult, FPGA timing
  difficult.
• Solution Turns out that if we hand off a task
  to hardware, its done by the next cycle! Simply
  have a single hardware string matcher.
• Run findHits() on a single database string and
  8000 neighbor words in 8030 NIOS cycles.

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System Architecture
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DSP Card
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NIOS
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NIOS-Hardware Interface
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String Matcher
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ARM
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Performance
Run time includes time to playback audio
encoding 3 times.
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War Stories

• Naju Write Once Memory
• Elliott Scriveners Tale
• Michael Matlab C
• Jon Wilsons Tearjerker

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The Atmel Chip Motivation

• Need to store CELP audio files for every virus in
  the 2MB database Flash chip
• Need to latch address bits since we dont have
  that many pins to give up.
• Basic operations
• flashread(), flashwrite(), flasherase()
• flashwrite() works sometimes.

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The Atmel Chip The Odyssey

• Time
• 1 day to wire-wrap latch (Elliot and Jon) and
  verify that it works with 5 NOP delay.
• 1 day to realize Flash chip was broken.
• 1 day to test new Flash chip.
• 1 day to realize all Flash chips are broken.
• 2 days to fix the Flash access functions, load
  and store CELP files, and add Flash-programming
  mode to server.

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The Atmel Chip Lessons Learned

• You can never spend too much time testing
  hardware. This is especially true when you
  consider spontaneous combustion.
• Maybe almost correct is good enough
• What saves us is error correction during decode.

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The Scriveners Tale

• It was a dark and stormy night
• A frustrated engineer and a DSP card sat alone
  together
• One was about to go flying out the window
• Learning about the DSP was hard
• Poor/hard to find documentation
• Whats that linker do, anyway?
• Lots of technical issues/quirks
• Them jumpers sure are purty.
• Can you hear me now? Why are there on board mics?
• Oh no! the interrupts didnt clear!
• Livelock??? Whats that?
• Hey Wilson, shouldnt that be a lt?
• Do you think the codec does sign-extension?
• Manuals dont always tell the whole story ?
• Vocoder 100, DSP 64
• Last minute architecture changes

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Stupid Bug

• Looks easy
• Port the code from Matlab to C
• Code seems to workmost of the time ?!
• Subtle difference in semantics between different
  programming languages
• Research code Matlab, SML, Modula3???
• Embedded System C, C, Java

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Matlab and C

• Matlab vector or matrix
• qry_seq qry_str(best_qry_lbest_qry_r)
• db_seq db_str(best_db_lbest_db_r)
• best_score b62_score(qry_seq,db_seq)
• C pointers
• best_score b62_score(char qry_s, char db_s)
• Seems to be right ???
• No!!!!
• qry_str(best_qry_lbest_qry_r) means the subset
  of the char vector starting from index best_qry_l
  to best_qry_r !!!!
• Something is missing..the LENGTH
• Possible solution b62_score(char qry_s, char
  db_s, int len)

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Other Gotcha

• Notice that the length cannot be hardcoded to be
  3
• Trim right and Trim left in the Matlab code means
  the length can actually varies from 1 to 3.
• Others
• Array indexing
• Matlab starts from 1
• C usually starts from 0
• Summary
• Make sure your assumption is correct when porting
  code from one language to the other (or from one
  platform to the other).
• Do extensive unit testing before code integration

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Wilsons Tearjerker

• Importance of personalities in a group
• I dislike all-nighters
• The others in my group seemed to love them
• Who is right? Should we stay up all night or
  spread our work out evenly? Must we choose?

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Group Dynamics

• The answer is compromise!
• I stayed up late on some occasions
• But we also worked during the day in effective
  blocks of time
• This would not have been possible without
  communication with the group
• Dont let those bad sentiments boil up be sure
  to voice your opinion

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SoC Design (Motivation)

• Integrated circuits are small, cheap, fast, and
  virtually indestructible after fabrication.
• Why redesign a DSP when we can drop in n DSP
  cores?
• Co-design hardware and software for system.
• Explore various designs, evaluating performance,
  identifying bottlenecks and cost.

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SoC Design (Reality)

• Every off-board chip we had burned out at least
  once many more than once.
• Although we have some freedom in designing
  hardware and software, changing a simply serial
  4-phase handshake interface can take hours.
• Performance is not easy to measure even if you
  know the average case.

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SoC Design (Ideal)

• Lets actually simulate. No hardware until we are
  done testing and measuring performance and even
  then, wire-wrap.
• Standard interface from one component to another
  (simply configure bus width).
• IDEs that dont work against you.
• (Correct) meaningful documentation. Just ask the
  NIOS people how its done.

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• QUESTIONS ?