Optical Simulation System for Brain Waves Detection & Measurements FRS Presenters: Yevgeny Safovich Nadav Pilnick Supervised By:Hen Brodney

Definition of Terms Element – a unit filled with a single color Pattern – collection of atomic Elements Step – definition of Patterns changing with a specified frequency and a D.C. Program – a set of Steps Supervisor – the programmer of the Patterns and the steps Operator – the tester of the person examined, will select the predefined steps

Problem Definition Measure eye vision quality objectively –The vision should be measured (almost) without cooperation of the person being examined

Project Objectives/Goals + Needs Analysis Output programmable Patterns by programmable Steps to the Monitor Output an electrical pulse The above should be synchronized The following should be programmable by the supervisor: –Programs –Patterns –Steps The following should be selected by the operator: –Select program to be used

Constraints & Definitions 3 pairs of colors: –Blue, Yellow –Green, Red –Black, White Each pair has its own “blank” color: the average of the colors in the pair Steps frequency: 0.5Hz – 10Hz, resolution 1Hz dx = The delta between the Monitor output and the electrical pulse output. 0.5ms < dx < 1.5ms

Solution Write a software application which will do the following: –Allow the supervisor to program the programs, steps, patterns for the required tests –Allow the operator to select a program to use –Output the programmed graphics to the monitor synchronized with an electrical pulse –The electrical pulse above will lead to a measurement of the waves within a human’s brain –The measurement of the waves within a human’s brain is out of the scope of the project. learn the video interface

Solution Algorithm Computer Monitor Video Card Human Brain Waves meter Operator * The red interfaces should be synchronized

Timing 0.5ms < |t5 – t3| < 1.5ms |t4 – t3|- We suppose this time does not matter and is taken care of by the “Brain Waves meter” |t3 – t2|- We suppose this interval is negligible |t2 – t1b|- The major problem of the project, discussed below |t5 – t1a|- A problem discussed below Computer Monitor Video Card Human Brain Waves meter Operator t t1b t3t4t2t5 t1a

Timing cont. We have 2 major issues: –Output of the graphics delay The time it takes for the screen to show the data since it was sent to the video card –Output of the electrical pulse delay The time it takes for the output port to change the output level since the opcode was sent to the processor Supposed the above are constant (deterministic) we can force synchronization

Pattern programming The way to define a pattern: –Squares: Size, Colors (2 colors) –Bands: Size, Colors, Type (horiz., vert.) –Q1: Element type –Q2: Element type –Q3: Element type –Q4: Element type Example: Pattern1 –Squares: 10, blue: red –Bands: 10,white:black,horiz –Q1: Squares –Q2: Bands –Q3: Blank –Q4: Blank Q1 Q4 Q2 Q3

Steps programming The way to define a step: –Patterns used –Duration (frequency) –D.C. Example: –Pattern1, Pattern2

Example of a program Program1: –Pattern:P1 Squares: 10, blue: red Bands: 10,white:black,horiz Q1: Squares Q2: Bands Q3: Blank Q4: Blank –Pattern:P2 … –Step:S1 P1:30%, P2:70% Frequency: 5Hz Duration = 2sec

Development Timeframes All major problems must be solved not later than in 2 weeks. The FRS must be completed not later than in 3 weeks The FRS should contain solutions and decisions for all issues mentioned in “Risks & Problems” on the following slides

Project Blocks Diagram The below is relevant only if the FRS is finished as stated above Programmable Module Electrical pulse Interface Video Interface Uni-Tests QA System Tests Arbiter – Main Application Module

Major Risks & Problems Is the synchronization accuracy of 1ms correct? The delay of the video card is unknown It takes the screen (5 – 10)ms (? – refresh rate) to draw the image. What should be the synchronization point ??? We have to catch a beginning of a Vertical Sync. of the image we sent. Verify the delay of an output port is constant and short enough.

Major Risks & Problems cont. Supposed the application is written in Windows we have the following problems: –There might be a Context Switch between 2 commands… –Does the Kernel run if the process’s priority is Real-Time –Video Card buffer’s delay is unknown (32 Mb) –Any HW access requires a device driver Supposed the application is written in DOS we have the following issues & problems: –Is direct writing to the Video memory possible? –Is the data sent to video card un-buffered? –Are video paging switches possible? How much time it takes to switch paging?

Gathered Information Maximum Refresh Rate: 200Hz ECP: output takes ~ 1microsecond There is a driver API allowing to block the application till the next Vertical Blank (Windows - DirectDraw)