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PS/2 mouse control using EOG/EMG signals. Group #9 Vikas Gupta Nick Chang. Overview. PS/2 mouse controlled with eyes Original Design Specification Deviations Functionality Tests Challenges Improvements Conclusion. Objective. Many people unable to use a mouse

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ps 2 mouse control using eog emg signals

PS/2 mouse control using EOG/EMG signals

Group #9

Vikas Gupta

Nick Chang

overview
Overview
  • PS/2 mouse controlled with eyes
  • Original Design
  • Specification Deviations
  • Functionality Tests
  • Challenges
  • Improvements
  • Conclusion
objective
Objective
  • Many people unable to use a mouse
    • Create a device which allows people to control mouse cursor with eye movements
  • Goals
    • Obtain useable logic signals from eyes
    • Convert signals into instructions the computer can understand
  • Personal Interests
    • Implement something cool!
original design
Original Design

Signal Filtering

and Amplification

EOG

electrodes

wires

Computer

Field Programmable

Gate Array

PS/2 male-male

connector

original design5
Original Design

Signal Filtering

and Amplification

EOG electrodes

obtaining the biosignal
Obtaining The Biosignal
  • 0.4 – 1 mV potential between Cornea and Retina
  • Use electrodes to measure potential
electrode placement
Electrode Placement
  • Red electrodes capture lateral eye movement
  • Blue electrodes capture vertical eye movement
  • Black electrode is common ground
amplification filtration isolation
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Ground

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

amplification filtration isolation9
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

amplification filtration isolation10
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

amplification filtration isolation11
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

amplification filtration isolation12
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

amplification filtration isolation13
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

amplification filtration isolation14
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

amplification filtration isolation15
Amplification, Filtration, Isolation

Non-

inverting

Amp

Rectifier

Up

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Down

Rectifier

Inverting

Amp

Ground

Non-

inverting

Amp

Rectifier

Right

4th Order

Filter

Input

Buffer

Diff.

Amp

Inverting

Amp

Summer

Circuit

Left

Rectifier

Inverting

Amp

Output

original design16
Original Design

Field Programmable

Gate Array

Computer

  • 2 main components:
    • Master State machine
      • Controls when the mouse should send/receive
    • Sensor Decision Logic
      • Convert inputs into mouse words
original design17
Original Design

Original Design

  • Block Diagram of FPGA components from our Design Review:

Mouse Word (3 bytes)

Left

Decision

Logic

State

Machine

Right

PS/2 Interface

Down

Up

Step Down Counter

15 kHz

PS/2 Oscillator

project build signal circuitry
Project Build – Signal Circuitry
  • Input Buffer
    • Unity gain
      • 3.3/3.3 = 1
project build signal circuitry19
Project Build – Signal Circuitry
  • Difference Amplifier
    • R1 = R2, R3 = R4
    • Av = R4 / R2
      • Av = 33/3.3 = 10V/V
project build signal circuitry20
Project Build – Signal Circuitry
  • 4th Order Butterworth Filter
    • Maximally flat passband
    • Cascade two 2nd order filters
  • H(s) = Avo/B(s)
    • B(s) = s2+1.414s+1
  • Avo = 3 – 1.414 = 1.586
    • Total gain = (1.586)*(1.586) = 2.515 V/V
  • 1.586 = R1’/R1
    • R1 = 10K, R1’ = 5.86K
  • Want Fo ~33 Hz
    • 33 = (2*pi*R*C)-1
      • Let R = 10K, C = 0.47uF
project build signal circuitry23
Project Build – Signal Circuitry
  • Inverting Amplifier
    • Avo = -R2/R1
  • Up/Down
    • Avo = -82/1.2 = 68.3 V/V
  • Left/Right
    • Avo = -68/1.2 = 56.6 V/V
project build signal circuitry24
Project Build – Signal Circuitry
  • Summer Circuit
    • Can add +/- 12V to input signal
  • Unity gain
    • 10/10 = 1 V/V
project build signal circuitry25
Project Build – Signal Circuitry
  • Inverting / Non Inverting Amplifier & Rectifier
  • Inverting Gain Non Inverting Gain

Avo = 33/3.3 = 10 V/V Avo = 1 + 33/3.3 = 11V/V

project build fpga mouse
Project Build – FPGA mouse
  • XSA-100 Prototyping Board
    • Conveniently comes with a PS/2 port
  • 555 IC Timer (x2)
    • Generation of arbitrary frequency clocks (a function of external R and C elements)
    • 30 kHz clock – PS/2 signal clock
    • slow clock – large state machine
project build fpga mouse28
Project Build – FPGA mouse

Input from

signal circuitry

Mouse Word

Generator

8-bit

Shift Register

(Command Word)

Onboard Display

Send/Receive

State Machine

Master State

Machine

Seven Segment

Decoder

30 kHz

555 Clk

PS/2 Signals

to Computer

~150 Hz

555 Clk

project build fpga mouse29
Project Build – FPGA mouse

Reset

If Reset = ‘1’

Init

NOT byte_received

Clk = ‘1’

Listen

Reset

Byte_received AND

command_word != ‘xF4’

Enable_sendbyte = ‘1’

psClk = 0->1, psData = ‘0’

(Request to Send state)

Byte_received AND

command_word = ‘xF4’

Send

byte_received = ‘1’

Setup

Response

States

Recieve

Send

Mouse

Words

Ready

Finished

functional tests
Functional Tests
  • Independent component tests were feasible with our design
    • FPGA mouse – switches/LEDs/Logic Analyzer
    • Signal circuitry – LEDs/Oscilloscope
challenges signal circuitry
Challenges – Signal Circuitry
  • Placement of Electrodes
    • Slight changes create affect dc baseline
    • Electrodes too large
  • Reliability of Signal
    • Looking “left” had an affect on “down”
challenges fpga
Challenges - FPGA
  • PS/2 protocol occurs at a frequency of 15kHz
    • Solution: 555 timer
  • Minor Detail – Major Hurdle!
    • PS/2 specification website
  • Large Number of States
    • A single byte transfer takes 22 states
  • Strict Timing Requirements
improvements
Improvements
  • Mouse button emulation
    • Implemented in FPGA, but not in signal circuitry
  • Blinking
  • Variable Amplifier Gain
  • DC Drift
  • PCB Implementation
conclusion
Conclusion
  • It worked!
    • 8 direction mouse movement
    • Functionality was as expected
  • Questions?