Play in the "Spinning Wheel" game is mediated by two sets of indicator lights: orange blinking LEDs that correspond to required user actions, and jumbo LEDs in a 'traffic light' configuration that communicate timer outputs to the user. In the following paragraphs, game play is described in relation to both sets of indicator lights.

During idle mode (between plays), a blinking LED next to the coin slot indicates that a coin is required for play to begin. At this time, the red traffic light is lit. After play is initiated, a second blinking LED next to the level-select knob turns the user's attention there. Three levels can be selected, which correspond to three possible speeds on the motor. After several seconds, a third blinking LED next to the ball-release mechanism suggests to the user that it is the appropriate time to release the contained balls. At this time, the amber traffic light is lit for ten seconds, building suspense for the beginning of play.

When the green traffic light goes on, the spinning wheel spins for the duration of the game. A large red LED above the wheel indicates each score, to a maximum of eight. Balls are stored in a tube next to the playing surface. With ten seconds remaining, the green traffic light is replaced by amber, and the end of the game is signaled both by a buzzer and the red traffic light. A blinking LED near the SWAG dispenser draws the user's attention there, and a prize is dispensed. The coin-deposit LED blinks again, waiting for the next user.

Coin Sensor: This opto-interrupter is a stock part from the ME218 lab. It contains a built-in IR LED and NPN phototransistor. In "Spinning Wheel", the opto-interrupter was fixed to the inside of the coin slot, such that a deposited penny would break the IR beam.

Level Selector: A potentiometer was used here as an analog input to the C32. Based on the resistive value, three settings were hard-coded to correspond to three motor speeds. The potentiometer was visually enhanced with a knob on the outside of the game.

Wheel Motor: Powered from the 12V supply, a resistor and reverse biased diode were used in parallel with the motor to damp down voltage spikes. Please see the schematics section for more information.

Scoring LEDs: Each LED was connected to the output of a 74HC164N shift register. The C32 was used to pulse the clock pin high and then low for each additional score.

SWAG Servo: The servo motor was powered with the 5V supply. Its third lead was connected directly to a C32 PWM pin. Changing the duty cycle of the signal through that output pin controlled the specific angle of action of the Servo.

Blinking LEDs: Controlled simply with an NPN transistor, these LEDs were purchased with the capability to blink at 2.4Hz. Current was managed with resistors.

Traffic light LEDs: Also controlled directly with an NPN transistor.

 

Wheel Motor: A geared DC Motor (Jameco PN: 253497PS) was used to direct drive the spinning wheel. It was powered by the 12V supply. The gear ratio was specifically chosen at 90:1 to make the game fun to play, and beatable.

SWAG Dispenser: This electromechanical system was designed to take a single acrylic disc from a stack and dispense it to the user, employing a 90° back and forth motion from the servo.

Ball Release Mechanism: Designed for user interaction, this simple gate confined the extra balls inside the holding tube until the user was ready to play.