Lesson 25 Simple Creation – Digital Dice

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Introduction

In previous experiments, we learned how to use a 7-segment display and control LEDs by a button. In this lesson, we will use a 7-segment display and a button together to create a simple digital dice.

Components

Schematic Diagram

The idea behind a digital dice is very simple: a 7-segment display circularly jumps from 1 to 7 rapidly. When the button is pressed, the jumping will slow down until it stops on a number. When the button is pressed again, the process will repeat.

Experimental Procedures

Step 1: Build the circuit.

Step 2: Open the code file. 

Step 3: Select the Board and Port.

Step 4: Upload the sketch to the board.

You can now see the 7-segment display jump between numbers from 1 to 6. Press the button, and the jumping will slow down until it stops three seconds later. Press the button again, and the process will repeat.

Code Analysis

Code Analysis 25-1  The initial random number comes from A0

randomSeed(analogRead(0));

The initial random number is generated from A0 and the range for the random numbers is 0-1023.

Code Analysis 25-2   Digital Dice

void loop()

{

  int stat = digitalRead(keyIn);  //store value read from keyIn

 if(stat == HIGH)  // check if the pushbutton is pressed, If yes, the corresponding pin is high level

 {

   num ++;  //num adds 1

  if(num > 1)  //If num > 1, clear the value. This is to prevent repeated pressing. So just count it as once no matter how many times you press.

{

      num = 0;

    }

  }  

Serial.println(num);  // print the num on serial monitor

  if(num == 1)  //when pushbutton is pressed

  {

    randNumber = random(1,7); //Generate a random number in 1-7 

    showNum(randNumber);  //show the randNumber on 7-segment

    delay(1000);  //wait for 1 second

    while(!digitalRead(keyIn));  //When not press button,program stop here  Make it keep displaying the last random number.

    int stat = digitalRead(keyIn);

    if(stat == HIGH) // check if the pushbutton is pressed

    {

      num ++;

      digitalWrite(ledPin,HIGH); //turn on the led

      delay(100);

      digitalWrite(ledPin,LOW); //turn off the led

      delay(100);

      if(num >= 1)

      {

        num = 0;

      }

    }      

  }

  //show random numbers at 100 microseconds intervals

   // If the button has not been pressed

  randNumber = random(1,7);

  showNum(randNumber);

  delay(100);

}

Code Analysis 25-3   showNum() function

void showNum(int num)

{

  digitalWrite(latchPin,LOW); //ground latchPin and hold low for transmitting

  shiftOut(dataPin,clockPin,MSBFIRST,datArray[num]);

  //return the latch pin high to signal chip that it

  //no longer needs to listen for information

  digitalWrite(latchPin,HIGH); //pull the latchPin to save the data

}

This function is to display the number in dataArray[] on the 7-segment display.