PRS Machine 2.0

Note

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Kit purchase

Looking for parts? Check out our all-in-one kits below — packed with components, beginner-friendly guides, and tons of fun.

Name	Includes Arduino board	PURCHASE LINK
Elite Explorer Kit	Arduino Uno R4 WiFi	BUY
3 in 1 Ultimate Starter Kit	Arduino Uno R4 Minima	BUY

Course Introduction

In this project, you will use an Arduino board, OLED screen, Active Buzzer, and an Ultrasonic Sensor Module to build a PRS machine2.0.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Arduino UNO R4 Minima/Arduino UNO R4 WIFI	1	BUY
2	USB Type-C cable	1
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	Ultrasonic Sensor Module	1	BUY
6	OLED Display Module	1	BUY
7	Active Buzzer	1

Wiring

Common Connections:

Active Buzzer
- ＋: Connect to 3 on the Arduino.
- －: Connect to breadboard’s negative power bus.
Ultrasonic Sensor Module Front
- Trig: Connect to 10 on the Arduino.
- Echo: Connect to 11 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.
OLED Display Module
- SDA: Connect to A4 on the Arduino.
- SCK: Connect to A5 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.

Writing the Code

Note

You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for Adafruit_GFX and Adafruit SSD1306 and install it.
Don’t forget to select the board(Arduino UNO R4 Minima/WIFI) and the correct port before clicking the Upload button.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED display settings
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SCREEN_ADDRESS 0x3C

// Bitmap size
#define ICON_WIDTH 64
#define ICON_HEIGHT 40

// Create OLED object
Adafruit_SSD1306 display(
  SCREEN_WIDTH,
  SCREEN_HEIGHT,
  &Wire,
  OLED_RESET
);

// Ultrasonic sensor pins
const int trigPin = 10;
const int echoPin = 11;

// Active buzzer pin
const int buzzerPin = 3;

// Prevent repeated triggers
bool hasPlayed = false;

// Icon animation timing
int currentIcon = 0;
unsigned long lastIconTime = 0;

// Time between icon changes
const unsigned long iconInterval = 100;

const uint8_t rockBitmap[] PROGMEM = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x20, 0x00, 0x7C, 0x7C, 0x00, 0x03, 0x00,
  0x00, 0x00, 0x00, 0xC1, 0x83, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x80, 0x01, 0xE0, 0x04, 0x00,
  0x00, 0x00, 0x03, 0x00, 0x00, 0xF0, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x18, 0x00, 0x00,
  0x00, 0x00, 0x7C, 0x00, 0x00, 0x0C, 0x00, 0x00, 0x0C, 0x00, 0x60, 0x00, 0x00, 0x0C, 0x00, 0x00,
  0x00, 0x00, 0x80, 0x00, 0x00, 0x0C, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x02, 0x02, 0x01, 0x80,
  0x00, 0x01, 0x80, 0x02, 0x02, 0x02, 0x01, 0x00, 0x00, 0x01, 0x00, 0x02, 0x01, 0x02, 0x00, 0x00,
  0x00, 0x06, 0x00, 0x01, 0x81, 0x01, 0x00, 0x00, 0xC0, 0x06, 0x01, 0x01, 0x80, 0x81, 0x00, 0x00,
  0x30, 0x04, 0x01, 0x00, 0x40, 0x81, 0x00, 0x00, 0x00, 0x08, 0x00, 0x80, 0x40, 0x41, 0x80, 0x38,
  0x00, 0x18, 0x00, 0x40, 0x20, 0x41, 0x00, 0x00, 0x00, 0x30, 0x00, 0x60, 0x30, 0x23, 0x00, 0x00,
  0x00, 0x30, 0x00, 0x20, 0x30, 0x23, 0x80, 0x00, 0x00, 0x30, 0x20, 0x10, 0x08, 0x3E, 0xE0, 0x00,
  0x00, 0x30, 0x10, 0x18, 0x08, 0x30, 0x60, 0x00, 0x00, 0x30, 0x10, 0x08, 0x04, 0xE2, 0x60, 0x00,
  0x00, 0x30, 0x08, 0x04, 0x07, 0x00, 0x60, 0x00, 0x00, 0x30, 0x08, 0x04, 0x07, 0x00, 0x60, 0x00,
  0x00, 0x18, 0x04, 0x02, 0x1C, 0x00, 0x60, 0x00, 0x00, 0x08, 0x06, 0x03, 0x18, 0x00, 0x60, 0x00,
  0x00, 0x06, 0x01, 0x01, 0xF0, 0x00, 0x80, 0x00, 0x00, 0x07, 0x01, 0x80, 0x60, 0xC1, 0x80, 0x00,
  0x00, 0x01, 0x00, 0x41, 0xA0, 0xDF, 0x00, 0x00, 0x00, 0x00, 0xC0, 0x3E, 0x30, 0xE0, 0x00, 0x00
};

const uint8_t scissorsBitmap[] PROGMEM = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x0E, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0E, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x11, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0xC0, 0x00, 0x00, 0x00,
  0x01, 0x00, 0x00, 0x20, 0xC0, 0x00, 0x00, 0x02, 0x00, 0x80, 0x00, 0x20, 0xC0, 0x07, 0xC0, 0x04,
  0x00, 0x40, 0x00, 0x20, 0xC0, 0x08, 0x30, 0x08, 0x00, 0x20, 0x00, 0x20, 0xC0, 0x08, 0x30, 0x30,
  0x00, 0x00, 0x00, 0x20, 0xC0, 0x18, 0x30, 0x00, 0x00, 0x00, 0x00, 0x20, 0xC0, 0x30, 0x20, 0x00,
  0x00, 0x00, 0x00, 0x20, 0xC0, 0x60, 0x60, 0x00, 0x00, 0x00, 0x00, 0x20, 0xC0, 0xC0, 0x80, 0x0C,
  0x00, 0x00, 0x00, 0x20, 0xC1, 0x81, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0xC3, 0x02, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x20, 0xC3, 0x06, 0x00, 0x00, 0x1E, 0x00, 0x00, 0x20, 0xC6, 0x06, 0x00, 0x03,
  0x03, 0x00, 0x00, 0x20, 0xCC, 0x08, 0x00, 0x06, 0x00, 0x00, 0x00, 0x20, 0xD0, 0x10, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x20, 0xF0, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x60, 0x60, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x40, 0x00, 0xF8, 0x00, 0x00, 0x00, 0x00, 0x00, 0xC0, 0x01, 0x88, 0x00, 0x00,
  0x00, 0x00, 0x03, 0x7F, 0xC3, 0x08, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x26, 0x0C, 0x00, 0x00,
  0x00, 0x00, 0x08, 0x00, 0x9C, 0x1E, 0x00, 0x00, 0x03, 0x00, 0x08, 0x00, 0x10, 0x13, 0x00, 0x04,
  0x1E, 0x00, 0x08, 0x00, 0x30, 0x21, 0x00, 0x03, 0x1C, 0x00, 0x08, 0x07, 0xF0, 0xC1, 0x00, 0x01,
  0x00, 0x00, 0x08, 0x01, 0x11, 0x81, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x8F, 0x07, 0x00, 0x00,
  0x00, 0x00, 0x04, 0x00, 0x82, 0x0E, 0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0x82, 0x18, 0x00, 0x00,
  0x00, 0x00, 0x03, 0x00, 0x81, 0xE8, 0x00, 0x00, 0x00, 0x00, 0x01, 0x81, 0x00, 0x18, 0x00, 0x00
};

const uint8_t paperBitmap[] PROGMEM = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x70, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xF0, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x1D, 0x98, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x22, 0x0F, 0xC0, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x42, 0x0C, 0x40, 0x00, 0x00, 0x00, 0x80, 0x00, 0x42, 0x0C, 0x20, 0x00, 0x04,
  0x00, 0x60, 0x00, 0x42, 0x0C, 0x20, 0x00, 0x18, 0x00, 0x20, 0x00, 0x42, 0x0C, 0x20, 0x00, 0x18,
  0x00, 0x10, 0x00, 0x42, 0x0C, 0x3E, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x0C, 0x33, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x42, 0x0C, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x0C, 0x21, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x42, 0x0C, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x0C, 0x21, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x42, 0x0C, 0x21, 0x00, 0x08, 0x00, 0x00, 0x00, 0x42, 0x0C, 0x21, 0x00, 0x30,
  0x03, 0xC0, 0xF8, 0x42, 0x0C, 0x21, 0x00, 0x00, 0x00, 0x00, 0x84, 0x42, 0x0C, 0xE1, 0x00, 0x00,
  0x00, 0x00, 0x83, 0x40, 0x00, 0x21, 0x00, 0x00, 0x00, 0x00, 0x81, 0x40, 0x00, 0x01, 0x00, 0x00,
  0x00, 0x00, 0x80, 0xC0, 0x00, 0x01, 0x00, 0x0F, 0x00, 0x00, 0xC0, 0xC0, 0x00, 0x01, 0x00, 0x0F,
  0x00, 0x00, 0x40, 0x21, 0xF8, 0x01, 0x00, 0x00, 0x00, 0x00, 0x20, 0x3C, 0x03, 0x01, 0x00, 0x00,
  0x01, 0xC0, 0x10, 0x03, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0xC0, 0x01, 0x00, 0x00,
  0x00, 0x00, 0x08, 0x00, 0x60, 0x01, 0x00, 0x10, 0x00, 0x30, 0x04, 0x00, 0x20, 0x01, 0x00, 0x18,
  0x00, 0x00, 0x04, 0x00, 0x10, 0x01, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x10, 0x01, 0x00, 0x00,
  0x00, 0x00, 0x03, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x80, 0x00, 0x02, 0x00, 0x00, 0x00, 0x08, 0x00, 0x40, 0x00, 0x06, 0x00, 0x20
};

void setup() {

  Serial.begin(9600);

  // Configure sensor pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Configure buzzer pin
  pinMode(buzzerPin, OUTPUT);

  // Create a random seed
  randomSeed(analogRead(A0));

  // Initialize OLED
  if (!display.begin(
        SSD1306_SWITCHCAPVCC,
        SCREEN_ADDRESS)) {

    Serial.println("OLED not found");

    while (true);
  }

  display.clearDisplay();
  display.display();
}

void loop() {

  // Read current distance
  float distance = readDistance();

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Object detected
  if (distance > 0 &&
      distance < 9 &&
      !hasPlayed) {

    // Pick a random result
    int result = random(0, 3);

    // Show result immediately
    showIcon(result, true);

    // Let OLED refresh first
    delay(50);

    // Play confirmation sound
    playResultSound();

    hasPlayed = true;

    if (result == 0) {
      Serial.println("Result: ROCK");
    }
    else if (result == 1) {
      Serial.println("Result: SCISSORS");
    }
    else {
      Serial.println("Result: PAPER");
    }
  }

  // Reset when clear
  if (distance >= 20 ||
      distance == -1) {

    hasPlayed = false;
  }

  // Cycle through icons
  if (!hasPlayed) {

    if (millis() - lastIconTime >= iconInterval) {

      lastIconTime = millis();

      showIcon(currentIcon, false);

      currentIcon++;

      if (currentIcon > 2) {
        currentIcon = 0;
      }
    }
  }

  delay(30);
}

// Measure distance in cm
float readDistance() {

  // Send trigger pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  long duration =
    pulseIn(
      echoPin,
      HIGH,
      30000
    );

  // No echo received
  if (duration == 0) {
    return -1;
  }

  // Convert to centimeters
  return duration / 58.0;
}

// Display selected icon
// 0 = Rock
// 1 = Scissors
// 2 = Paper
void showIcon(
  int icon,
  bool isResult) {

  display.clearDisplay();

  if (isResult) {
    drawSparkles();
  }

  if (icon == 0) {

    display.drawBitmap(
      32,
      5,
      rockBitmap,
      ICON_WIDTH,
      ICON_HEIGHT,
      SSD1306_WHITE
    );

    drawLabel("ROCK", 52);
  }

  else if (icon == 1) {

    display.drawBitmap(
      32,
      5,
      scissorsBitmap,
      ICON_WIDTH,
      ICON_HEIGHT,
      SSD1306_WHITE
    );

    drawLabel("SCISSORS", 40);
  }

  else {

    display.drawBitmap(
      32,
      5,
      paperBitmap,
      ICON_WIDTH,
      ICON_HEIGHT,
      SSD1306_WHITE
    );

    drawLabel("PAPER", 49);
  }

  display.display();
}

// Draw icon label
void drawLabel(
  const char *text,
  int x) {

  display.setTextColor(
    SSD1306_WHITE);

  display.setTextSize(1);

  display.setCursor(x, 54);

  display.println(text);
}

// Draw result effect
void drawSparkles() {

  display.drawLine(
    14, 18,
    22, 18,
    SSD1306_WHITE);

  display.drawLine(
    18, 14,
    18, 22,
    SSD1306_WHITE);

  display.drawLine(
    106, 18,
    114, 18,
    SSD1306_WHITE);

  display.drawLine(
    110, 14,
    110, 22,
    SSD1306_WHITE);

  display.drawLine(
    14, 42,
    22, 42,
    SSD1306_WHITE);

  display.drawLine(
    18, 38,
    18, 46,
    SSD1306_WHITE);

  display.drawLine(
    106, 42,
    114, 42,
    SSD1306_WHITE);

  display.drawLine(
    110, 38,
    110, 46,
    SSD1306_WHITE);
}

// Play a simple confirmation beep
void playResultSound() {

  digitalWrite(
    buzzerPin,
    HIGH);

  delay(120);

  digitalWrite(
    buzzerPin,
    LOW);

  delay(80);

  digitalWrite(
    buzzerPin,
    HIGH);

  delay(120);

  digitalWrite(
    buzzerPin,
    LOW);
}