GAME BOX

Building the Project

Mini-Lesson: Understanding Multiplexing for the TM1637 Display

Shared Control Lines:

The TM1637 display has two main control lines: CLK (clock) and DIO (data input/output). These lines are used to send data to the display module, which then handles the multiplexing internally.

Time Division Multiplexing (TDM):

The display works by rapidly cycling through each of the four digits, turning each digit on and off in quick succession. This cycling happens so fast that the human eye perceives all digits as being on simultaneously. Due to the persistence of vision, where the eye retains an image for a fraction of a second after the object is gone, the rapid on-off cycling of each digit creates the illusion of a stable, continuous display.

Segment Control:

For each digit, the TM1637 controller sends a set of data that determines which segments of that digit should be lit. The controller sends data to each digit one at a time, enabling the correct segments for each digit in turn.

Data Transmission:

Data is transmitted serially to the TM1637 display. Each digit is addressed in turn, and the data for that digit’s segments is sent. The CLK line is used to synchronize the transmission, and the DIO line carries the actual segment data.

Updating Display:

The display controller updates each digit in sequence. While the first digit is being updated, the others are temporarily turned off. This process repeats for each digit. The setSegments function takes an array of segment data and updates the display accordingly.

Benefits of Multiplexing

• Reduced Pin Count: By multiplexing, fewer pins are needed on the microcontroller to control multiple segments, as all segments share the same control lines.

• Simplified Wiring: The use of multiplexing simplifies the wiring needed to connect the display to the microcontroller.

• Cost Efficiency: Fewer components are required, reducing the overall cost of the project.

In summary, multiplexing in the TM1637 display enables efficient control of multiple 7-segment digits with minimal wiring and pin usage, providing a seamless and effective way to display numeric data.

TM1637 Game Box Code

#include <TM1637Display.h>

// Define the connections pins for the TM1637

#define CLK 3

#define DIO 2

// Define the button pin

const int buttonPin = 4;  // Main button

// Define the potentiometer pin

const int potPin = A0;

// Create an instance of the TM1637 display

TM1637Display display(CLK, DIO);

// Modes

enum Mode {

  MODE_6_SIDED_DIE,

  MODE_20_SIDED_DIE,

  MODE_HEADS_TAILS,

  MODE_TIMER

};

Mode currentMode = MODE_6_SIDED_DIE;

bool stopwatchRunning = false;

unsigned long stopwatchStartTime = 0;

unsigned long countdownDuration = 180000; // Initial countdown duration: 3 minutes in milliseconds

unsigned long elapsedTime = 0;

void setup() {

  // Initialize the display

  display.setBrightness(0x0f); // Max brightness

  // Initialize the button pin as input with pull-up resistor

  pinMode(buttonPin, INPUT_PULLUP);

  // Seed the random number generator

  randomSeed(analogRead(0));

}

void loop() {

  // Read the potentiometer value and map it to the mode range

  int potValue = analogRead(potPin);

  int modeIndex = map(potValue, 0, 1023, 0, 3);

  currentMode = static_cast<Mode>(modeIndex);

  // Display the mode (0, 1, 2, 3)

  display.showNumberDec(modeIndex);

  // Read the state of the button

  int buttonState = digitalRead(buttonPin);

  // Check if the button is pressed

  if (buttonState == LOW) {

    switch (currentMode) {

      case MODE_6_SIDED_DIE:

        rollDice(6);

        break;

      case MODE_20_SIDED_DIE:

        rollDice(20);

        break;

      case MODE_HEADS_TAILS:

        displayHeadsTails();

        break;

      case MODE_TIMER:

        startTimer(countdownDuration);

        break;

    }

    // Debounce delay

    delay(200);

    // Wait until the button is released to avoid multiple actions

    while (digitalRead(buttonPin) == LOW) {

      delay(10);

    }

  }

}

void rollDice(int sides) {

  int roll = random(1, sides + 1);

  display.showNumberDec(roll);

  // Wait until either the button is pressed again or the potentiometer is adjusted

  while (true) {

    int potValue = analogRead(potPin);

    int modeIndex = map(potValue, 0, 1023, 0, 3);

    if (static_cast<Mode>(modeIndex) != currentMode || digitalRead(buttonPin) == LOW) {

      return;

    }

  }

}

void displayHeadsTails() {

  bool result = random(0, 2);

  if (result) {

    displayHead(); // Display "HEAD"

  } else {

    displayTail(); // Display "TAIL"

  }

}

void displayHead() {

  uint8_t head[4] = {

    SEG_G | SEG_B | SEG_C | SEG_E | SEG_F,              // H

    SEG_A | SEG_F | SEG_G | SEG_E | SEG_D,              // E

    SEG_A | SEG_B | SEG_F | SEG_G | SEG_E | SEG_C,       // A

    SEG_A | SEG_B | SEG_F | SEG_E | SEG_C | SEG_D,       // D

  };

  display.setSegments(head);

}

void displayTail() {

  uint8_t tail[4] = {

    SEG_G | SEG_F | SEG_E | SEG_D,                       // t

    SEG_A | SEG_B | SEG_F | SEG_G | SEG_E | SEG_C ,       // A

    SEG_B | SEG_C ,                                     // I

    SEG_F | SEG_E | SEG_D ,                             // L

  };

  display.setSegments(tail);

}

void startTimer(unsigned long countdownDuration) {

  // Calculate countdown duration based on potentiometer value

  stopwatchRunning = true;

  stopwatchStartTime = millis();

  elapsedTime = 0;

  while (stopwatchRunning) {

    unsigned long currentTime = millis() - stopwatchStartTime;

    // Calculate remaining time

    unsigned long remainingTime = countdownDuration - currentTime;

    // Calculate minutes and seconds

    unsigned int minutes = (remainingTime / 60000) % 60;

    unsigned int seconds = (remainingTime / 1000) % 60;

    // Display the time in MM:SS format

    uint8_t timeDisplay[4];

    timeDisplay[0] = display.encodeDigit(minutes / 10);  // Tens of minutes

    timeDisplay[1] = display.encodeDigit(minutes % 10);  // Units of minutes

    timeDisplay[2] = display.encodeDigit(seconds / 10);  // Tens of seconds

    timeDisplay[3] = display.encodeDigit(seconds % 10);  // Units of seconds

    // Set colon ':' between minutes and seconds

    timeDisplay[1] |= 0x80; // Add colon to the second digit (units of minutes)

    display.setSegments(timeDisplay);

    delay(200); // Update display every 200 milliseconds

  }

}