Pinball MachineMei LiCaleb Whitehead

EGGN 383 Final Project

May 1, 2013

Project overviewObjective: small-scale pinball machine

Operations:○ User pushes a button to swing the paddle○ Machine records number of times the ball enters

different regions, using IR break-beam sensors○ Game over when the ball escapes 3 times○ The goal is to get as many points as possible

Mei

Hardware - Diagram

Score Regions

Escape Region

Mei

Hardware - ComponentsServo motors

○ swing the paddle○ operate on 6 V (Vservos)○ 60o rotation

Pushbuttons○ control the servo motors○ active high with pull-up

resistorhttp://image.made-in-china.com/2f0j00geNanjyoSZbY/Push-Button-Switch-PBS-28B-2L-.jpgMei

Hardware - Components

IR Break-Beam Sensors

○ detect the ball○ update the score○ modulated by 555

timer

Liquid crystal display (LCD)○ GDM2004D module○ Hitachi HD44780U controller○ display the scores○ display "escape" counter

Mei

Hardware - Components

http://www.circuitstoday.com/wp-content/uploads/2009/09/555-timer-ic-identification.jpg

http://upload.wikimedia.org/wikipedia/commons/thumb/3/3d/555_Astable_Diagram.svg/500px-555_Astable_Diagram.svg.png

LM 555CN Timer○ provide 38kHz signal for modulating the IR

emitter ○ configure in astable mode○ C = 1nF, R1 = 1kΩ, R2 varies

Mei

Schematic

Caleb

Software - Design Controlling the paddles

○ impulse vs holdInterrupts vs. PollingFrom PWM system to Servo outputsUse of PortAD for LCD

Caleb

Software - PseudocodeInitialize

LCD (on PortAD)PWM system (on PortT)IR sensors (already set as inputs on PortM)Set score to zeroSet number of escapes left to three

Caleb

Software - PseudocodePoll

Drive motor forward if button depressedDrive motor back if button releasedWaiting = 1 if score sensor detects ballIncrease score, waiting = 0 if score sensor doesn't detect ball and waiting = 1 If escape sensor detects ball, wait until escape sensor doesn't detect ball, then decrease escapes leftUpdate counters on the LCDDisplay "Game Over" if no escapes leftWhile (Game Over) enter infinite loop to disable game

Caleb

Challenges Pushbuttons

○ bouncing on input captureMotors

○ interfering with each otherIR Break-Beam Sensors

○ used 555 timer instead of function generatorMechanical construction

○ mounting of components

Caleb

SummaryDesign and implement a small-scale pinball machine

○ Use HCS12 microcontroller for interfacing○ Pushbutton activates the motor○ Motor swings the paddle to hit the ball○ IR sensors detect the ball○ LCD displays the scores

Mei

Questions or clarifications or suggestions?

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