Help for Diecimila-based digital clock.

Hi folks
I'm new to this site and to Arduino so bear with me if I ask some stupid newbie questions.
The deal is I want to build a digital clock (hh:mm) using an Arduino Diecimila and 5mm LED's for the digits. I have a huge pile of LED's lying around so I think I'll use 4 LED's for each segment in each 7-segment digit, which amount to 112 LED's.
The problem is how to make the Arduino drive 28 segments and keep track of the time?
I've read a bit about Charlieplexing, and it should be possible to use this method, but it will get a bit complex. Is there an easier way?
And I've found some examples of Clock code but they all seem too complicated, I only need minutes and hours and not date or alarms. I would also like to be able to set the time on the clock after a reset without connecting to a computer, maybe just by using two buttons that increment the hours and minutes by 1 when pressed?
So please help me with my first Arduino project.

Best regards
Morten

Hi Morton,

If you use the DateTime library in the playground, your code could be something like this

#include <DateTime.h>

int minutesSwitch = 2;
int hoursSwitch = 3;

void setup(){
  pinMode(minutesSwitch, INPUT);
  pinMode(hoursSwitch, INPUT);
  DateTime.sync(0);  // clock will start at midnight  
}

void  loop(){
   DateTime.available(); //refresh the Date and time properties
   if(digitalRead(minutesSwitch))  // note that these switches may need to have debounce code added !
         DateTime.sync(DateTime.now() + 60);   // add 60 seconds to time if switch is pressed
    if(digitalRead(hoursSwitch)) 
         DateTime.sync(DateTime.now() + 60 * 60); // add an hour to the time if the hour switch is pressed      
    displayMinutes(DateTime.Minute);
    displayHours(DateTime.Hour);   
}

void    displayMinutes( byte minutes){
   // your code to display minutes here 
}

void displayHours(byte hours){
   // your code to display hours here   
}

It will need work on the display and handling the switch input, but the library will handle the time functions

Hi Mem
Thanks, that absolutely looks useable. Can I use the DateTime library for my clock and the just print hours and minutes on my display?

Yes, I have modified the sketch above slightly, you can use the value of minutes and hours in the two functions as needed.

Cool. But I think I have to figure out exactly how the DateTime library works before i fully understand your piece of code. I presume I need more code to get a working clock than what you wrote.