Built In Test Software for Deformable Mirror University of Hawaii

							Built-In Test Software for Deformable Mirror High Voltage
                          Drivers




                          Jianwei Zhou
         Home Institution: University of Hawaii at Manoa
                 CfAO Akaimai Intership 2008
                        Subaru Telescope
                     Mentor: Stephen Colley



        Funding provided by the Center for Adaptive Optics through its
       National Science Foundation Science and Technology Center grant
                                                                         1
                               (#AST-987683)
           Today’s Presentation

   Background Info
   Design Discussion
   Problems (Solved& Unsolved)
   Results




                                  2
                          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
   I2C – Inter-Integrated Circuit
   LGSAO – Laser Guide Star Adaptive-Optics




                                               3
                 Project Overview
   Design Built-In Test (BIT) software for
    deformable mirror high voltage driver in the
    Subaru LGSAO system.

Measurement performed by BIT circuitry
 Input Voltages

 Output Voltages

 Power Supply Voltages

 Board Temperature




                                                   4
            Deformable Mirror (DM)




   DM is used with wavefront sensor to provided optical control and correction.

   DM operates with maximum voltages of +400V, and HV amplifiers with gain of 40
    are used to amplify input voltages of + 10v to +400v.
                                                                                   5
                HV Driver Subsystem

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




                                                         6
High Voltage Amplifier Board




                               7
                                                                    High Voltage
Low Voltage                                                          Connector
 Connector    Differential Input
                                    HV Amplifiers
                  Amplifiers                                         HV Input

 LV Input
               Amplifiers
                                                                     HV Power


 LV Power      Low Voltage
                Regulator

               Power


                                                    Build In Test
  BIT
 Network
               LV Dividers
                                   HV Dividers               AD
                                                    MUX                     MC
                                                           Converter
              Amplifiers


                                                                                8
       Importance of Built-In Test Software



            Digital
                                  + 10v               + 400 v

Real-Time   Data                   188      HV          188
                        D/A
 Control                                  Amplifier             DM
                      Converter
Computer                                   Board
                       Board
                                           w/BIT




                                                                     9
              Built-In Test Circuit
Main components:
         Analog Multiplexer
         Analog-To-Digital Converter
         Microcontroller (PIC 16F877)           BIT
         Temperature Sensor                     Circuit




                                   Microcontroller          Host
                    A/D
       Mux                                                Computer
                  Converter


                                    Temperature
                                       Sensor                  10
                       Programming
    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

   Debugging require the knowledge of microcontroller
                                                         11
          Programming

5 Functions total:

MAIN+PORT+ MUX+ADC+I2C+TEMP




                              12
                     Set Up

   Problem: The C compiler cannot installed and
    compiled properly

   Solution: Read the user manual and get help
    from product website




                                                   13
Memory Constraint of Microcontroller
   Problems:
    Programs must fit in the available on-chip program
    memory ( very small compare to computer)

   Solution:
    Must optimize the code to reduce the memory
 I Displayed the measurement as character instead of int (char 8
   bit, int 32 bits)
II Reduced the number of variable
III Reduced the lines of code whenever possible
                                                                   14
         Low Level Programming

   Problems: Must understand the characteristic
    of the hardware when programming



   Solution: Reading the data sheet of the
    hardware.


                                                   15
                 Debugging

   In-Circuit Debugger




                             16
MPLAB IDE




            17
                            Results
   Tested the BIT circuit
    1 bad A/D converter is found in one board
    Fabrication error is found( The pin layout of temperature
    sensor on the board is different from the schematic diagram)

   Measures the input voltages, output voltages, and power
    supply voltages by the BIT software on a HV amplifier board

   A bug in the PICC STD is found ( cannot insert leading 0
    with sprintf function)




                                                                   18
         Work To Be Completed


   Run the BIT software in the whole LGSAO
    system
   Communication between the BIT circuit and
    host computer (I2C)




                                                19
              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


                                                20
               Acknowledgements
   Stephen Colley, Mentor
   Sarah Anderson, Hawaii Island Internship Coordinator
   Lynne Raschke, Science Communication Lead Instructor
   Scott Seagroves, Science Communication Co-instructor
   Lisa Hunter, Akamai Intership Director




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