Lesson 23 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.

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.

The schematic diagram:

../_images/image252.png

Experimental Procedures

Step 1: Build the circuit

../_images/image211.png ../_images/image253.png

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.

../_images/image254.jpeg

Code

Code Analysis

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.

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)
   {
      num = 0;
   }
}

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.

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 ++; // num+1=2
         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);
}

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.