Clocks are a rite of passage for hardware hackers, and with this video you can start working on your DIY Clock merit badge using the Arduino platform to build a basic Arduino clock. This project builds on the Arduino Fortune Teller project from the “Arduino For Kooks” basic series and teaches programming concepts like timing and actively updating a display, so you can use it as a springboard for many more complicated projects!

PARTS/TOOLS:

(Most of these can be found in the Arduino Starter Kit available here)

Arduino UNO

1602 LCD

Solderless breadboard

Assorted resistors (220 and 10K, specifically)

Jumper (Dupont) Wire

10K Potentiometer

Tactile switches

The Circuit:

Connect the LCD module as described in the Liquid Crystal Ball project. You can use the breadboard to create buses for +5V and GND. Connect one side of one tactile switch to D8 and the other to a 10K resistor to ground. Connect one side of the other tactile switch to D9 and the other side to a 10K resistor to ground.

The Sketch:

//Projet ColorTyme
//Phase 1: Simple LCD Clock
//CC-BY-SA Matthew Eargle
//AirborneSurfer.com
//element14 Presents

#include "LiquidCrystal.h"

// Define LCD pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

// initial Time display is 00:00:00 (24hr clock)
int h=00;
int m=00;
int s=00;

// Time Set Buttons
int button1;
int button2;
int hs=8;// pin 8 for Hours Setting
int ms=9;// pin 9 for Minutes Setting

// Digital LCD Constrast setting
int cs=6;// pin 5 for contrast PWM
static int contrast=100;// default contrast

//Define current time as zero
static uint32_t last_time, now = 0;

void setup()
{
lcd.begin(16,2);
pinMode(hs,INPUT_PULLUP);
pinMode(ms,INPUT_PULLUP);

now=millis(); // read RTC initial value
analogWrite(cs,contrast);
}

void loop()
{
// Update LCD Display
// Print TIME in Hour, Min, Sec
lcd.setCursor(0,0);
lcd.print("Time ");
if(h<10)lcd.print("0");// always 2 digits
lcd.print(h);
lcd.print(":");
if(m<10)lcd.print("0");
lcd.print(m);
lcd.print(":");
if(s<10)lcd.print("0");
lcd.print(s);

lcd.setCursor(0,1);// for Line 2
lcd.print("SURF STD TIME");

while ((now-last_time) < 1000 ) // wait1000ms
{
now=millis();
}

last_time=now; // prepare for next loop
s=s+1; //increment sec. counting

/-------Time setting-------/
button1=digitalRead(hs);
if(button1==0)
{
s=0;
h=h+1;
}

button2=digitalRead(ms);
if(button2==0){
s=0;
m=m+1;
}

analogWrite(cs,contrast); // update contrast

/* ---- manage seconds, minutes, hours am/pm overflow ----*/
if(s==60){
s=0;
m=m+1;
}
if(m==60)
{
m=0;
h=h+1;
}
if (h==25)
{
h=0;
}

}