ELECTRICAL DESIGN

Schematic

Component breakdowns

PIC32

The PIC32 Microcontroller controlls all the logic for the game, with outputs going to the LEDs and LED Matrix, and inputs coming from the buttons, button sensor, and microphone envelope.

Microphone

The microphone circuit takes an amplified audio input, filters it using a low pass filter, then uses an envelope detector to detect the instantaneous sound level. The output is then fed through a voltage comparer to make the signal 0-3.3V. Finally, the output is used to drive a red LED to give the user feedback on the current noise level.

PUSH BUTTONS

The buttons are standard normally-open buttons, with a circuit to prevent debouncing.

LEDs

The eight LEDs use the +5V power supply for power, as they draw too much current to be driven directly with the PIC32. They are each toggled by a 2N7000 transistor, which allows the PIC32 to turn the LEDs on and off with minimal current draw.

LED Matrix

The LED matrix is a MAX7219 SPI-controlled LED matrix. A SN74HC244N Octal Buffer is used to step the input signal up from 3.3V to the necessary 5V.

COIN DETECTOR

The coin detector is an optocoupler without a part number from Amazon. It has a built in LM393 comparator, which is connected to the digital out (DO) pin and outputs 0V when a coin is present, and +VCC otherwise.

SERVO

The servo is a standard MG995 servo, which uses the PWM signal to select a position between 0º and 180º.

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