A.R. HertnekyJ.W. O’Brien

J.T. ShinC.S. Wessels

Laser Controller One (LC1)

www.teamvice.net

January 31, 2006 Preliminary Design Review (PDR) 2

Outline

• Background• Functionality• Block diagrams/sub-

systems• Parts list/budget• Schedule/division of labor• Risk analysis

January 31, 2006 Preliminary Design Review (PDR) 3

Background

• Physics experiments often require laser cooling– Bose-Einstein

Condensate (BEC)– atomic fountain clock

• Laser wavelength locked to hyperfine transition– analog control system– Doppler-free saturated

absorption spectroscopy (sat spec)

January 31, 2006 Preliminary Design Review (PDR) 4

Background

• Establishing/maintaining lock is operator intensive– non-intuitive– manual system

monitoring required

• Incompatible with automated lab equipment

January 31, 2006 Preliminary Design Review (PDR) 5

Functionality

• Auto-magically scans atomic spectrum

• Identifies absorption peaks

• Operator selects a reference peak

• Configures analog control equipment

• Lock is engaged

January 31, 2006 Preliminary Design Review (PDR) 6

Functionality

A manual operator would…• observe erroneous

behavior in experiment• discover broken lock

through troubleshooting• repeat procedure to

establish lock from scratch

Our device will…• sense problem• recalibrate and

reestablish the lock• return to normal

operation within seconds

If the lock is lost

January 31, 2006 Preliminary Design Review (PDR) 7

User Interface

• Front panel status– LCD

• available absorption peaks• currently selected reference peak• time since last lock status change

– Two-color LED• quick visual: locked/unlocked

– Keypad or dial• choose peak and initiate automatic behavior

January 31, 2006 Preliminary Design Review (PDR) 8

Hardware Environment

Laser /Saturated Absorption

SpectroscopyLoop Filter Peak Lock

Laser Controller One (LC1)

Switch

January 31, 2006 Preliminary Design Review (PDR) 9

External Connections

Laser Controller One (LC1)

Spectrum Output(Saturated Absorption

Spectroscopy)

Error Offset Monitor(Loop Filter)

Error Monitor(Peak Lock)

Offset Control(Loop Filter)

Sweep(Loop Filter)

Switch(Peak Lock/Loop Filter)

LegendInput

Output

Digital Interconnect

Analog Interconnect

January 31, 2006 Preliminary Design Review (PDR) 10

Hardware Subsystems

Laser Control One (LC1)

A/D D/A

LCDDisplay

CPU

FPGADigilent Spartan 3 Development

Board

FlashMemory

InputDevice

(Dial/Keypad)

Bus

UART OtherIP

1MBSRAM

January 31, 2006 Preliminary Design Review (PDR) 11

Microcontroller

Freescale M683XX Microcontroller• Clock speeds for wire wrapped prototype (8-

12MHz) and PCB integration (15-20MHz) • Integrated Memory Controller• LQFP 144, PQFP 132, QFP 144 Packages

January 31, 2006 Preliminary Design Review (PDR) 12

FPGA Module

Digilent Spartan-3 Starter Board

• XC3S1000 Core• 1000k gate version• 1 Megabyte of SRAM• 2 Megabits of platform

flash• 50 MHz oscillator• 3 x 40-pin I/O headers

January 31, 2006 Preliminary Design Review (PDR) 13

Optional FPGA Sub-modules

• Memory (Flash/SRAM)• Test Point Header• Serial I/O• R2R Module (8-bit DAC up to 25MHz)• Two A/D 12-bit converter chips• Two D/A 8-bit converter chips• RS232 converter• Four high bright LEDs• 6-pin header to two BNC connectors

January 31, 2006 Preliminary Design Review (PDR) 14

Software/Hardware Division

CPU•User Interface

– LCD Display– Keypad

•Remote control•System management

FPGA•Laser control interaction•Signal processing•Application specific functions•System monitoring

January 31, 2006 Preliminary Design Review (PDR) 15

Estimated Cost

Component Price2 Spartan3 FPGA Boards $150.00 eaPCB etching (2 revisions) $200.00LCD $300.00Power Supply $100.00Keypad/Dial $25.00Chassis $100.00Flash Memory $50.00Misc/Unforeseen Expenses $225.00Total $1,300.00

January 31, 2006 Preliminary Design Review (PDR) 16

Risks and Contingency Plan• Risks

– unfamiliarity with DSP and control systems– system and algorithmic complexity– integration with automated environment a

large task• Contingencies

– utilize classmates and instructors– modularize and reduce interdependencies– limit project scope

January 31, 2006 Preliminary Design Review (PDR) 17

Schedule

January 31, 2006 Preliminary Design Review (PDR) 18

Project Responsibilities• A.R. Hertneky

– PCB layout, FPGA development, laser system modifications

• J.W. O’Brien– System-level software, chassis/UI design, test

procedure design• J.T. Shin

– Analog interfaces, FPGA on-chip peripherals, peripheral simulation

• C.S. Wessels– Graphical LCD driver, FPGA development, boot

loader and CPU firmware

January 31, 2006 Preliminary Design Review (PDR) 19

Thank you. Questions?

“I don’t know; and when I know nothing, I usually hold my tongue.”

– Creon in Oedipus the King