OVERVIEW
In a prior tutorial we created a countdown timer using an 8bits Display.
Unfortunately the display we used when creating the tutorial, is getting harder to find.
So we created a similar tutorial using this easier to find 8bits Display that is using the MAX7219.
PARTS USED
8 Digits 7 Segment Module
Passive Buzzer Module
Arduino UNO
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CONNECTIONS
Here are the connection needed for this tutorial:
GND pins from the UNO are connected to the negative (-) pin of the buzzer and GND pin of the display.
The 5V pin of the UNO is connected to the VCC pin of the display
Pin 5-6-7 of the UNO are connected to pin CS-CLK-DIN of the display
Pin 8 of the UNO is connected to the positive (+) pin of the Buzzer
THE CODE
We are using the LedControl library by Eberhard Fahle to communicate with the MAX7219 Display.
More information about the library can be found here: http://playground.arduino.cc/Main/LedControl
As always for more information about the tutorial and explanation of the code please watch our tutorial video.
/* CountDown Timer version 2 using Max7219
Created by Yvan / https://Brainy-Bits.com
This code is in the public domain...
You can: copy it, use it, modify it, share it or just plain ignore it!
Thx!
*/
#define Max7219DIN 7 // Pin 7 connected to DIN (DataIN)
#define Max7219CLK 6 // Pin 6 connected to CLK
#define Max7219CS 5 // Pin 5 connected to CS
#define Buzzer 8 // Pin 8 connected to Buzzer +positive pin
int BuzzTrigger=0; // Variable to store buzzer trigger value
#include "LedControl.h" // LedControl Library created by Eberhard Fahle at http://playground.arduino.cc/Main/LedControl
LedControl lc=LedControl(Max7219DIN,Max7219CLK,Max7219CS,1); // Last number represent the number of Max7219 Modules connected
long int countnumber=24001000 ; // Countdown timer start value HH:MM:SSSS
// Variables to store individual numbers
int firstnum=0;
int secondnum=0;
int thirdnum=0;
int fournum=0;
int fivenum=0;
int sixnum=0;
int sevennum=0;
int eightnum=0;
void setup() {
lc.shutdown(0,false); // Wake up the display
lc.setIntensity(0,7); // Set Brightness 0-15
lc.clearDisplay(0); // Clear display
pinMode(Buzzer, OUTPUT);
digitalWrite(Buzzer, LOW); //Buzzer Off at startup
}
void loop() {
for (countnumber; countnumber != -1; countnumber --)
{
String mystring = String(countnumber); // Transform Counter Int to String for manipulation
// Convert number to a time value
for (int z = 0; z < 6; z++){
if ( mystring.substring(z) == "999999" ) {
countnumber = (countnumber - 400000);
}
if ( mystring.substring(z) == "9999" ) {
countnumber = (countnumber - 4000);
}
}
// Display number on Display depending on number of digits remaining
if (countnumber > 9999999) {
firstnum = ((countnumber/10000000)%10);
secondnum = countnumber/1000000%10;
thirdnum = countnumber/100000%10;
fournum = countnumber/10000%10;
fivenum = countnumber/1000%10;
sixnum = countnumber/100%10;
sevennum = countnumber/10%10;
eightnum = countnumber%10;
lc.setDigit(0,7,firstnum,false);
lc.setDigit(0,6,secondnum,false);
lc.setDigit(0,5,thirdnum,false);
lc.setDigit(0,4,fournum,false);
lc.setDigit(0,3,fivenum,false);
lc.setDigit(0,2,sixnum,false);
lc.setDigit(0,1,sevennum,false);
lc.setDigit(0,0,eightnum,false);
}
else {
if (countnumber > 999999) {
// firstnum = ((countnumber/10000000)%10);
secondnum = countnumber/1000000%10;
thirdnum = countnumber/100000%10;
fournum = countnumber/10000%10;
fivenum = countnumber/1000%10;
sixnum = countnumber/100%10;
sevennum = countnumber/10%10;
eightnum = countnumber%10;
lc.setChar(0,7,'-',false);
lc.setDigit(0,6,secondnum,false);
lc.setDigit(0,5,thirdnum,false);
lc.setDigit(0,4,fournum,false);
lc.setDigit(0,3,fivenum,false);
lc.setDigit(0,2,sixnum,false);
lc.setDigit(0,1,sevennum,false);
lc.setDigit(0,0,eightnum,false);
}
else {
if (countnumber > 99999) {
// firstnum = ((countnumber/10000000)%10);
// secondnum = countnumber/1000000%10;
thirdnum = countnumber/100000%10;
fournum = countnumber/10000%10;
fivenum = countnumber/1000%10;
sixnum = countnumber/100%10;
sevennum = countnumber/10%10;
eightnum = countnumber%10;
lc.setChar(0,7,'-',false);
lc.setChar(0,6,'-',false);
lc.setDigit(0,5,thirdnum,false);
lc.setDigit(0,4,fournum,false);
lc.setDigit(0,3,fivenum,false);
lc.setDigit(0,2,sixnum,false);
lc.setDigit(0,1,sevennum,false);
lc.setDigit(0,0,eightnum,false);
}
else {
if (countnumber > 9999) {
// firstnum = ((countnumber/10000000)%10);
// secondnum = countnumber/1000000%10;
// thirdnum = countnumber/100000%10;
fournum = countnumber/10000%10;
fivenum = countnumber/1000%10;
sixnum = countnumber/100%10;
sevennum = countnumber/10%10;
eightnum = countnumber%10;
lc.setChar(0,7,'-',false);
lc.setChar(0,6,'-',false);
lc.setChar(0,5,'-',false);
lc.setDigit(0,4,fournum,false);
lc.setDigit(0,3,fivenum,false);
lc.setDigit(0,2,sixnum,false);
lc.setDigit(0,1,sevennum,false);
lc.setDigit(0,0,eightnum,false);
}
else {
if (countnumber > 999) {
// firstnum = ((countnumber/10000000)%10);
// secondnum = countnumber/1000000%10;
// thirdnum = countnumber/100000%10;
// fournum = countnumber/10000%10;
fivenum = countnumber/1000%10;
sixnum = countnumber/100%10;
sevennum = countnumber/10%10;
eightnum = countnumber%10;
lc.setChar(0,7,'-',false);
lc.setChar(0,6,'-',false);
lc.setChar(0,5,'-',false);
lc.setChar(0,4,'-',false);
lc.setDigit(0,3,fivenum,false);
lc.setDigit(0,2,sixnum,false);
lc.setDigit(0,1,sevennum,false);
lc.setDigit(0,0,eightnum,false);
}
else {
// firstnum = ((countnumber/10000000)%10);
// secondnum = countnumber/1000000%10;
// thirdnum = countnumber/100000%10;
// fournum = countnumber/10000%10;
// fivenum = countnumber/1000%10;
sixnum = countnumber/100%10;
sevennum = countnumber/10%10;
eightnum = countnumber%10;
lc.setChar(0,7,'-',false);
lc.setChar(0,6,'-',false);
lc.setChar(0,5,'-',false);
lc.setChar(0,4,'-',false);
lc.setChar(0,3,'-',false);
lc.setDigit(0,2,sixnum,false);
lc.setDigit(0,1,sevennum,false);
lc.setDigit(0,0,eightnum,false);
}
}
}
}
}
// If one second as gone by sound buzzer
if (BuzzTrigger == 99){
digitalWrite (Buzzer, HIGH) ;// Buzzer On
delay (9) ;// Delay 2ms
digitalWrite (Buzzer, LOW) ;// Buzzer Off
BuzzTrigger = 0; // Trigger for countdown sound
}
else {
delay (9);
BuzzTrigger = BuzzTrigger + 1;
}
// If countdown at zero sound alarm and flash display
if (countnumber == 0) {
for (int y = 0; y < 8; y++){
digitalWrite (Buzzer, HIGH) ;// Buzzer On
for (int x = 0; x < 8; x++)
{
lc.setDigit(0,x,0,false);
}
delay (100) ;// Delay 1ms
digitalWrite (Buzzer, LOW) ;// Buzzer Off
for (int x = 0; x < 8; x++)
{
lc.setChar(0,x,'-',false);
}
delay (300) ;// delay 1ms
}
}
}
}TUTORIAL VIDEO
DOWNLOAD
Copy the above Sketch code in your Arduino IDE software to program your Arduino.
Used Libraries:
Download the LedControl library here: LedControl Library Download Page
Once downloaded, just extract the content of the zip files inside your “arduino/libraries” folder.
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