Built-In Test Software for Deformable Mirror High Voltage Drivers

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Built-In Test Software for Deformable Mirror
High Voltage Drivers

• Jianwei Zhou
• Home Institution University of Hawaii at Manoa
• CfAO Akaimai Internship 2008
• Subaru Telescope
• Mentor Stephen Colley
• Funding provided by the Center for Adaptive
  Optics through its National Science Foundation
  Science and Technology Center grant (AST-987683)

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Todays Presentation

• Background
• Importance of Build-In Test software
• Design Process
• Conclusion
• Acknowledgement

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Acronyms

• A/D Analog to Digital
• D/A Digital to Analog
• BIT- Built-In Test
• DM- Deformable Mirror
• HV High Voltage
• ICD In-Circuit Debugger
• LGSAO Laser Guide Star Adaptive-Optics
• MUX Multiplexer

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Project Overview

• Design Built-In Test (BIT) software for
  deformable mirror high voltage driver in the
  Subaru LGSAO system.
• Measurements performed by BIT circuitry
• Input Voltages
• Output Voltages
• Power Supply Voltages
• Board Temperature

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Deformable Mirror (DM)

• DM is used with wavefront sensor to provided
  optical control and correction.
• The DM is divided into 188 segments with separate
  control voltage to each segment
• DM operates with maximum voltages of 400V, and
  HV amplifiers with gain of 40 are used to amplify
  input voltages of 10v to 400v.

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HV Driver Subsystem

• The HV driver subsystem in the Subaru LGSAO
  system consist of 10 HV Amplifier boards

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High Voltage Amplifier Board
HV Amplifiers
Built-In Test
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Importance of Built-In Test Software
Real-Time Control Computer
DM
10v
400 v
D/A Converter Board
HV Amplifier Board w/BIT
Digital Data
188
188
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Built-In Test Circuit

• Main components
• Analog Multiplexer (Mux)
• Analog-To-Digital Converter
• Microcontroller (PIC 16F877)
• Temperature Sensor

BIT Circuit
Mux
Microcontroller
Host Computer
A/D Converter
Temperature Sensor
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Built-In Test Software

• Program Language use C
• Step 1 Program in C
• Step 2 Compile to Assembly language by PICC
  STD.
• Pros and cons
• C is easier and much shorter than assembly
  language
• Programming requires the knowledge of
  microcontroller

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In-Circuit Debugger

• Real-time debugger and programmer

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MPLAB IDE
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Memory Constraints of Microcontroller

• Programs must fit in the available on-chip
  program memory ( very small compare to computer)
• Must optimize the code to reduce the memory

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Conclusion

• Tested the BIT circuit
• 1 bad A/D converter is found in one board
• Fabrication error of temperature sensor
• BIT software successfully measures the input
  voltages, output voltages, and power supply
  voltages on a HV amplifier board

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Work To Be Completed

• Communication between the BIT circuit and host
  computer
• Run the BIT software in the whole LGSAO system

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Personal Thought

• A valuable opportunity to learn about circuit
  design
• Application of the knowledge learnt in school to
  real life practice
• Increased research ability
• Increased Confidence

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Acknowledgements

• Stephen Colley, Mentor
• Akamai Internship staff
• Sarah Anderson, Hawaii Island Internship
  Coordinator
• Lynne Raschke, Science Communication Lead
  Instructor
• Scott Seagroves, Science Communication
  Co-instructor
• Lisa Hunter, Akamai Internship Director