Multi-threaded projects Services and Drivers

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Multi-threaded projectsServices and Drivers

• Alternate ways of doing Labs 1, 2, 3 and 4.

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ENCM415 Ideal final project

• Plans for a complete Lab. 4
• Run the audio input and output (Lab. 0)
• Reading the light sensor (Lab. 2)
• Reading the thermal sensor (Lab. 3)
• Displaying values in the Flash LED (Lab. 1)
• Displaying values on the external LCD screen over
  the SPI interface (Lab. 4)
• Using interrupts (Labs. 2, 3 and 4)
• Control that robot car (Lab. 17) and plane (Lab.
  22000)
• Do-able with knowledge we already have
• Spend 40 hours to complete is there a simpler
  way

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A simpler way

• Some teams prefer to use development approaches
  essentially equivalent to what we have done in
  Labs 1, 2 and 3
• Becomes easier with practice, but does not come
  easy.
• Other teams are using prepared code from the
  manufacturer.
• Threads
• Services and Drivers
• Reliability issues forcing manufacturers to
  ensure prepared code works well

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Doing Lab. 4 project in industry

• We might not develop a final .dxe executable
• We might get each task to run by its self
• Then add each task as a thread inside a
  multi-threaded operating system.
• The processor (using core timer interrupts) would
  automatically switch between tasks as each data
  became available
• Easier to integrate new Lab. with the previous
  labs
• Straight forward to do with Analog Devices VDK
  Visual DSP Kernel, uCLinux, uC-OS etc etc

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Initialization Thread
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Main Thread example
While task pends (wait till ready), it
automatically gets switched out of the processor
Each Lab. 4 task has its own threadfunction
which replaces the sleep
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VDK History shows tasks switched out when they
have to wait
Concept of task priority
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Would VDK make 415 easier

• NO, using VDK would make 415 harder as you have
  another interface to learn
• How do you debug a function (LED display) when
  the function works with one thread and not with
  another?
• Answer with great difficulty
• But learning VDK would make the ENCM491 (real
  time) and ENCM515 (DSP architectures) easier to
  learn as you could cut 6 weeks out of each class
  because of the extra 6 weeks needed in ENCM415 (a
  saving of 6 weeks).

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Would threads make industry easier?

• PROBABLY NOT, using threads the first time makes
  the project harder, you have another interface to
  learn
• However PROVIDED the real-time operating system
  is inexpensive and reliable you have a common
  interface that many developers on your team can
  all use. Product is shorter time and lower cost
• However, many developers dont want to use
  commercial OS as too slow, too difficult to
  customize for the product. They would rather use
  the techniques you have used in ENCM415.
• Also, using threads only changes about 20 of the
  code you have to develop. Basically all you have
  is better while loops and easier semaphores
  andmessaging

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System Services

• Much of this presentation is based on Analog
  Devices on-line Blackfin training by David
  Lannigan at
• my.analog.com/onlinetraining/Static/BOLDList.html
• There are audio and video presentations on
• Blackfin Device Drivers (May 2006)
• Blackfin System Services (Jan. 2006)
• Introduction to VDK (Sept. 2006)
• It is recommended that users have some
  understanding of the Blackfin architecture, basic
  knowledge of software terminology and experience
  in embedded systems. Meaning have taken ENCM415

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Would system services help in ENCM415?

• For Labs. 1, 2 and 3 No
• You have to know the sort of thing that is
  supposed to happen with the hardware in some very
  simple cases (Flash memory, GPIO, LEDs)
• How do you start an interrupt?
• How do you build an interrupt service routine?
• How can you build a fast ISR in assembly code?

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Would system services help in Lab. 4?

• System services provide you all the functions
  that you developed in Labs. 1, 2 and 3 for GPIO
  etc
• If the services are simple to learn how to use
  for GPIO control, then perhaps we can quickly get
  it to work for the SPI interface.
• Analog Devices has just recently updated their
  services software, so using services has
  potential

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Proposed Lab. 4 Demo-based

• Demonstrate in class using services to do Labs. 1
  and 2
• 50 -- Connect LCD screen to logic lab and
  switches. Place commands in an array. Manually
  (using switches) send commands to LCD screen to
  show Happy 415 Christmas
• 30 -- Demonstrate Lab. 4 Temperature and Light
  sensor using You will need to add a modified
  CalculateTemperature( ) from Lab. 3 and the PF9
  service
• 20 -- Add a SPI SERVICE to transfer the
  commands from the Blackfin to the LCD

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All true, the third timeyou try using
it However, thats what you do inan industrial
environment
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VDK
All the non-hardwarestuff from Lab. 1, 2 and3
stays the same
All the hardwarestuff from Lab. 1, 2 and3
better?
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Powerful once we know how to use it
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Lots of new syntax to learn
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Something related to Lab. 2
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Some of these functions are recognizable
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Interrupt handler hidden
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But there is much to learn
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Service for fast memory transfer
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Sounds like Lab. 2
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Many functions recognizable
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Perhaps try for Lab. 4