Software utilization of a sensor signal

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Software utilization of a sensor signal
Sensors Technology MED4

Lecturer Smilen Dimitrov
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Introduction

• The model that we introduced for ST

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Introduction

• The part where we focus in this lecture

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Data acquisition (DAQ) systems

• Main purpose measuring and digitizing sensor
  signals.
• Basic structure single channel DAQ
• Basic parameters sampling resolution and
  sampling period
• Repeat using applet
• Teleo

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Data acquisition (DAQ) systems

• Teleo is a multichannel DAQ system a DAQ board
• 4 inputs performance issues

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Computer architecture and program execution

• The hardware nature demands translation of the
  high level program

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Computer architecture and program execution

• The hardware nature demands translation of the
  high level program

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Computer architecture and program execution

• Once on the machine level, the program is
  executed sequentially, synced by a clock signal

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Computer architecture and program execution

• Once on the machine level, the program is
  executed sequentially, synced by a clock signal

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Computer architecture and program execution

• Execution of a machine instruction requires
  complex synchronization between the parts of the
  computer clock several stages of execution

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Computer architecture and program execution

• Fetch execute cycle
• Use PC to supply adress,
• Get instruction from memory,
• read registers,
• Use instruction to decide what to do,
• Solve instruction, write registers,
• Update PC.

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Computer architecture and program execution

• Fetch execute cycle and timing

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Computer architecture and program execution

• We implement branching by manipulating the
  program counter PC from sequential execution
  to loops
• Although we should in general avoid fixed /
  endless loops, that is how the OS and the
  computer works on a low level - continuity

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Computer architecture and program execution

• New processes are started from an OS kernel that
  runs in an infinite loop
• Each individual process thread requires resources
  time slots to execute / computer clock ticks
  performance issues when calculating media

//process CPU instructions until the next screen
redraw while(!vertical_retrace)
tickspassedcpu_ProcessNextInstruction()
interrupts_Process(tickspassed)
video_Process(tickspassed)
sound_Process(tickspassed) //etc. for other
components
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Computer architecture and program execution

• Same endless loop metaphor when calculating media
  drawing methods that repeat as long as the
  program is running (rate say 25 fps)
• Same endless loop metaphor when reading and
  applying sensor signals application depends
  completely on our design video audio render
  frames
• Interrupt / variable as a way to intervene in the
  endless loop

While (1) var a ReadSensorValue(1) ApplyVal
ue(a)
While (1) var a ReadSensorValue(1) DrawCurr
entFrame(a)
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Practical issues

• Practical issues around interfacing a data
  acquisition and software utilisation.
• Here for our chosen board, Teleo Intro by Making
  Things (see separate document on Sensor Tech
  website)
• Installing the Teleo driver
• Preparing the Teleo
• Example Flash program
• Example Max program
• Example Java via Max program