Binary clock uses DS3232 RTC

[Kenneth Finnegan] quenches our clock-a-day compulsion with his Arduino based binary timepiece. The clock uses a 5×7 LED matrix as a display and shows month, day, and time. He sourced a DS3232 real-time clock which automatically compensates for temperature to achieve very accurate time keeping. We like the super-cap circuit he added to keep the RTC running if the power is cut.

Is an Arduino overkill here? Well, the code is certainly not filling the 16k available on the ATmega168. At $4.32, the $1-2 you could save by using a lower-grade chip is not worth having to rewrite the code developed during prototyping. [Kenneth] also mentions that these projects usually only hang around for a few weeks before they’re re-purposed for the next endeavor.

Take a look at [Kenneth's] superb hardware walk through in the video after the break.  If you’re a fan of clean breadboarding, he’s also made a time-lapse of the circuit building process.

Clock components explained

Time-lapse of circuit building.

Comments

  1. googfan says:

    love them tin-can transistors!

  2. Sprite_tm says:

    What Arduino? I see a nice AVR on a breadboard. If anything, not using the hardware means that there’s thought been put into what to use, something some other Arduino-projects lack.

  3. john personna says:

    Concur with Sprite.

  4. osgeld says:

    arduino is also software, in fact its mostly software set on a nice little prototyping board, which is totally optional (as shown)

  5. Kyle says:

    I suppose it could be considered an Arduino project due to the software, but I wouldn’t consider it so. He built this thing from an ATMega. Right there, he’s demonstrated that he at least knows enough about electronics to not have to use a prefabricated board. I generally see the Arduino as an electronics “training wheels” system – good for teaching beginners, but something to move past after you’ve mastered it. And, honestly, although he might have been able to do the same thing with a lower end ATMega, it is reusable for other projects, and I see no problem with that. Well done, sir!

  6. Plasmator says:

    Yeah, not an Arduino per se. Probably just using the term as shorthand to refer to the ATMega 168 + Arduino bootloader.

  7. nubie says:

    I guess the question is whether or not the Arduino bootloader an arduino makes.

    Either way I wonder why an Atmega8 or ATiny couldn’t have been used. Probably no reason but that he had these on hand.

    I am very interested in the Super Capacitors that supposedly keep it powered for days, possibly longer if you turn off features of the clock chip.

    I would love to see a DIY watch/clock for under $20 that used an ATiny and the cheaper clock chip he mentions.

    In fact I wonder if you can scavenge a rt clock from an old motherboard.

  8. Whatnot says:

    I never used a breadboard, always seems more for kids and stuck with soldering circuits, after drawing them out on paper, routing it in my head, but I admit I sometimes thought later I could have done better :)
    And it’s more for very simple stuff I guess.
    Maybe I should get a breadboard though, I’m more in tune with a make-and-disassemble way now.

    Weird to me to see the digital in a vertical view actually on that video, I wonder if that’s how it’s suppose to be viewed in the endproduct, it doesn’t hinder the reading of it though, not more than a horizontal view I mean, perhaps it’s even better than the horizontal which I would tend to pick due to always seeing binary in horizontal on computers.

  9. Chris says:

    Agree with Sprite, also quite impressed that it only really took a couple of attempts to get the firmware doing what was required…. I normally find there are *several* bugs that take a while to figure out, though the code for most of my projects would be well over 10kb as they have been several month long projects….

  10. osgeld says:

    lol you super “hackers” are tickling me today

    if its on a printed board and someone mentions arduino all hell breaks loose

    stick a chip with the exact same software on it and it becomes worthy

  11. TJ says:

    @osgeld
    Yes apparently hacking has been reduced to an inverse relationship to the number of hoops you have to jump through to get the job done.

  12. Brian says:

    @nubie et al: I’d argue that it’s not the use of the Arduino bootloader (which is really just the STK500 bootloader with a few modifications) but the use of the Arduino software libraries that make something an Arduino project.

    The amount of memory used is also a really bad way to decide whether a chip is overkill. I’ve designed some hardware around the mega168 that uses nearly every single pin, all of the inputs to the ADC (including the two only available on the surface-mount versions), the I2C and UART interfaces, and two of the three timers. I came nowhere near using the full 16K of flash available. Does that mean the chip I chose is overkill?

    It would be great if we could quit judging projects so much by whether or not they use an Arduino and just evaluate them on their own merits.

  13. MrX says:

    @Kyle

    “Right there, he’s demonstrated that he at least knows enough about electronics to not have to use a prefabricated board.”

    Bullshit. So you never use prefabricated boards? You etch everything? Your PC motherboard, FPGAs?

    Yeah.. right..

  14. Kyle says:

    @MrX

    I don’t consider building a PC to be a hack. In fact, I consider it something that’s almost foolproof due to the inherent modularity of it. I mean, if you can plug it in backwards, it generally doesn’t hurt to do so. The same cannot necessarily be said of raw electronics.

    Now, I have nothing against the Arduino. I’m of the opinion that it’s actually been very beneficial to the hacking community in general due to the ability for beginners to build projects far above their competency level, which gives them the confidence to learn more. But it frustrates me to see people perpetually using overkill components. It gives me the feeling that they don’t understand the underlying theory of the components they’re using. That philosophy is why I stopped subscribing to electronics magazines years ago – they were all about using large, expensive building blocks rather than actually learning how to move electrons around.

    But then, I like programming in assembler, so maybe it’s just me. :)

  15. mc says:

    A question
    Where did you get that nice DIL carrier for the DS3232 (RTC) – all the SMT carrier boards I find are clunky oversized.

  16. Agent420 says:

    Regarding the arduino software/ide, though I joke about arduinos from time to time I could see how it would be more appealing than the alternative free gcc based compilers. Personally, I think the gnu toolchains are a pita; a decent commercial compiler is an excellent investment if you do much with avr’s.

  17. ReKlipz says:

    @Kyle

    I like to move holes, it’s seven times the fun!

  18. Agent420 says:

    @Kyle

    agreed. it’s funny how so many people these days can program something as ‘complex’ as an ardunio module, yet not have a clue how to calculate the resistance of an led resistor or how to use a transistor to switch a relay.

  19. Kyle says:

    @ReKlipz

    Touché!

  20. Wow. Thanks for all the support, guys.

    @mc: The DIL carrier is from Digikey, and is linked to in the parts list.

    I do have a few ATtiny2313s laying around, but haven’t figure out how to do I2C without the direct hardware support on the mega168 yet. I’m working on it.

    No question Arduino really got me into digital electronics, and I’ve been working my way down from there, but keep using it to implement the parts I don’t know how to do otherwise yet. I’m still calling it an Arduino at this point, because I’m making magical I2C library calls that I haven’t bothered to implement on my own yet.

  21. AO says:

    I definitely think it’s the easy access to libraries that make Arduino so popular and such a “standard” starting point for so many projects. Sure you can find pick the right chip on a project-by-project basis, but when you’re doing a lot of one-offs, the few dollars you’d save by going with a smaller micro. isn’t a huge motivator, as was motioned above.

  22. error404 says:

    @Ken:

    Peter Fleury has a great AVR I2C master library available that can either use the built-in TWI module or bit-banged I/O. That is if you don’t like reinventing the wheel and want to get away from Arduino, anyway :p

    http://homepage.hispeed.ch/peterfleury/avr-software.html

  23. Coolins says:

    This is a very simple and cheap circuit but very nice and accurate clock given a good power supply.

  24. caliel says:

    “If you want to make an apple pie from scratch, you must first create the universe.”

    –Carl Sagan

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