# 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

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