Digital Clock Block Diagram

Discussion in 'Homework Help' started by Wendy, Dec 8, 2008.

  1. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,765
    2,536
    We seem to be getting a lot of queries about Digital Clocks, so I've drawn up this block diagram to help out. If anyone (especially the mods) can suggest improvements please do.

    [​IMG]
     
    Last edited: Dec 9, 2008
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Another clocksource can be a 32768 Hz crystal oscillator
    (from an old digital watch for instance)
    with a 32768 divider to get the 1 Hz reference for the seconds.

    Greetings,
    Bertus
     
  3. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,765
    2,536
    True enough, but what do you think most of the students are being assigned? From what I can tell, these courses are being given as a practical assignment in flip flops and counters.

    I didn't realize how wide this diagram wanted to be when I started. :rolleyes:
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    With a crystal oscillator you are independend of the line frequency.
    You could even make a CMOS version on batteries.
    (though the display will take some current when not multiplexed).

    Greetings,
    Bertus
     
  5. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,765
    2,536
    I don't think any of these guys are actually building this sucker. If you go through the last 5 or so posts asking for help they come up with "I don't have a clue where to start" or a simple "HELP!". I only wish the clocks I buy used something so good, for the most part they seem to have a poorly adjusted RC oscillator when the power goes out and the battery backup takes over. This really is the commercial standard.

    This is meant as a starting point for these guys. If you and I were to build the clock this would be totally unnecessary. Near as I can figure, over half of the old hands would start off with a microcontroller.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The number of counters isn't too bad, but the PCB gets awfully busy if you're just using logic.

    I am pretty past it, but I lost interest pretty seriously about the time 8 bit systems went away. But I'm about to glom onto the STK500 and a clock is my first project. Got lotsa LED's for it - gonna track seconds (also stay busy at the drill press for a bit).
     
Loading...