Lesson 25 Simple Creation – Digital Dice

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

Experimental Principle

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.

The schematic diagram:

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);   // Read the state of the button again. 
    if(stat == HIGH)                // check if the pushbutton is pressed.If yes, run the code below
    {
      num ++;
      pinMode(ledPin, OUTPUT);      //initialize the digital pin as an output
      digitalWrite(ledPin, HIGH);   //turn on the led 
      delay(100);
      digitalWrite(ledPin,LOW);     //turn off the led 
      delay(100);
      if(num >= 1)                  // clear the num
      {
        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,HIH);    //pull the latchPin to save the data
}