11

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 (#AST-98

7683)

22

Today’s Presentation

Background Info Design Discussion Problems (Solved& Unsolved) Results

33

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

44

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

55

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.

66

HV Driver Subsystem

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

77

High Voltage Amplifier BoardHigh Voltage Amplifier Board

88

Low VoltageConnector

LV Input

LV Power

BIT Network

Differential InputAmplifiers

HV Amplifiers

Amplifiers

Low Voltage Regulator

Power

LV DividersHV Dividers

Amplifiers

High VoltageConnector

HV Input

HV Power

MUXAD

ConverterMC

Build In Test

99

Real-TimeControl

Computer

D/A Converter

Board

HVAmplifier

Boardw/BIT

DM

188

+ 10v

188

+ 400 vDigital

Data

Importance of Built-In Test Software

1010

Built-In Test CircuitMain components:

Analog Multiplexer

Analog-To-Digital Converter

Microcontroller (PIC 16F877)

Temperature Sensor

Mux A/D Converter

Microcontroller

Temperature Sensor

Host Computer

BIT Circuit

1111

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

1212

Programming

MAIN+PORT+ MUX+ADC+I2C+TEMP

5 Functions total:

1313

Set Up

Problem: The C compiler cannot installed and compiled properly

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

1414

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 bit

s)

II Reduced the number of variable

III Reduced the lines of code whenever possible

1515

Low Level Programming

Problems: Must understand the characteristic of the hardware when programming

Solution: Reading the data sheet of the hardware.

1616

Debugging

In-Circuit Debugger

1717

MPLAB IDE

1818

Results Tested the BIT circuit 1 bad A/D converter is found in one board Fabrication error is found( The pin layout of temperature sens

or 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)

1919

Work To Be Completed

Run the BIT software in the whole LGSAO system

Communication between the BIT circuit and host computer (I2C)

2020

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

2121

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

2222