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Lesson 42: Digital Dice

This program simulates a dice roll using an OLED display. The simulation is triggered by shaking the vibration switch, causing the display to cycle through numbers 1 to 6, akin to rolling a dice. The display halts after a short duration, revealing a randomly selected number that represents the dice roll outcome.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Universal Maker Sensor Kit	94	Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction	Purchase Link
ESP32 & Development Board (ESP32 Board)	BUY
Vibration Sensor Module (SW-420)	BUY
OLED Display Module (SSD1306)	-
Breadboard	BUY

Wiring

Code

Note

To install the library, use the Arduino Library Manager and search for “Adafruit SSD1306” and “Adafruit GFX” and install it.

Code Analysis

A comprehensive breakdown of the code:

1. Initialization of variables:

   vibPin: Digital pin connected to the vibration sensor.

   const int vibPin = 35;    // The pin where the vib switch is connected
   

2. Volatile variables:

   rolling: A volatile flag that indicates the dice’s rolling status. It is volatile as it is accessed within both the interrupt service routine and the main program.

   volatile bool rolling = false;
   

3. setup():

   Configures the vibration sensor’s input mode. Assigns an interrupt to the sensor to trigger the rollDice function upon state change. Initializes the OLED display.

   void setup() {
       // Initialize pins
       pinMode(vibPin, INPUT);
   
       // initialize the OLED object
       if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
           Serial.println(F("SSD1306 allocation failed"));
           for (;;)
           ;
       }
   
       // Attach an interrupt to the vibPin. When the vib switch is activated, the shakeDetected function will be called
       attachInterrupt(digitalPinToInterrupt(vibPin), rollDice, CHANGE);
   }
   

4. loop():

   Continuously checks if rolling is true, displaying a random number between 1 and 6 during this state. The rolling ceases if the sensor has been shaken for over 500 milliseconds.

   void loop() {
       // Check if it's rolling
       if (rolling) {
           byte number = random(1, 7);  // Generate a random number between 1 and 6
           displayNumber(number);
           delay(80);  // Delay to make the rolling effect visible
   
           // Stop rolling after 1 second
           if ((millis() - lastShakeTime) > 1000) {
               rolling = false;
           }
       }
   }
   

5. rollDice():

   The interrupt service routine for the vibration sensor. It initiates the dice roll when the sensor is shaken by recording the current time.

   // Interrupt handler for shake detection
   void rollDice() {
       if (digitalRead(vibPin) == LOW) {
           lastShakeTime = millis();  // Record the time of shake
           rolling = true;            // Start rolling
       }
   }
   

6. displayNumber():

   Displays a selected number on the OLED screen.

   // Function to display a number on the 7-segment display
   void displayNumber(byte number) {
       display.clearDisplay();  // Clear the screen
   
       // Display Text
       display.setTextSize(4);       // Set text size
       display.setTextColor(WHITE);  // Set text color
       display.setCursor(54, 20);     // Set cursor position
       display.println(number);
       display.display();  // Display the content on the screen
   
   }