Fubarino Contest: Persistence of Vision clock

propellerck5

The best part of these contests is that we get people to actually show off what they’ve been working on! Check out the POV clock which was sent in by [Taciuc]. He doesn’t have a webpage for it, but he did send a video which you can see after the break.

The project is a home-etched PCB with a long row or surface mount LEDs. The board is spun by a stepper motor which takes a little while to stabilize. But once it does it’s a twirling package of awesomeness. A PIC 16F628 drives the device, with a separate RTC chip to keep time. There’s also an IR receiver to facilitate user control. Our URL is displayed on the clock face itself and we think it’s always shown. But there is an easter egg in the code itself. If you try to dump the firmware from the chip you’ll see our web address in the hex output. Here’s his project archive if you want to the HEX, ASM and DipTrace schematic.


This is an entry in the Fubarino Contest for a chance at one of the 20 Fubarino SD boards which Microchip has put up as prizes!

Comments

  1. netbeard says:

    I would have made it display hackaday at 1:37pm (13:37)

  2. Timsie says:

    How is power transfer accomplished? Is it a slip ring? Induction?

  3. ElectroNick says:

    Nice looking clock!

    That is pretty darn fast for a stepper. It actually looks like a BLDC motor from an old floppy, maybe I missed something in his explanation?

    • garym53 says:

      He does say stepper but perhaps he made a mistake there. There doesn’t seem to be enough cables leading to the motor for it to be a stepper.

      I have managed 750 RPM with a stepper but it was a very difficult task with very slow ramping required to get over the steppers resonance points.

      • mess_maker says:

        I noticed it looked like the motor stalled when he started powering it. Maybe that was an oddity because if frame rate and the spin of the clock – but at a glance ( with the sound down ) my thought was that it stalled. Anyway, if that’s true then I would imagine it was actually a stepper.

        • Marius says:

          it is a HDD stepper motor driven by 6 MOS transistors. It really spins around 3000rpm refreshing the image at around 50Hz. It took me a while to write the code for the driver, and I only managed to make it stable by taking the time to settle in a certain position befor it starts the sequence. I used four corner pads on the PCB and I balanced the entire device by adding tin to these pads.

          • garym53 says:

            I hate to be contradictory but as far as I am aware all HDD motors are brushless 3 phase motors (except in some old drives where the head was moved by a stepper but they wouldn’t do 3000 rpm that’s for sure).

            I would not mind in the least being proved wrong but the fact you are using 6 MOS transistors implies 3 phases – if you could post the schematic or motor winding diagram that would prove it one way or the other. Cheers.

  4. garym53 says:

    I would very much like to know how he managed to get a stepper motor up to 3000 RPM – that is some feat!

  5. says:

    If hackaday.com is permanently displayed on the clock face, I’d be surprised to not see the same string in the firmware binary. Although the screenshot shows some additional text which is presumably never displayed…

    • Greenaum says:

      Well, no, since it’s not like you can just printf() to a spinning disk o’ LEDs. The Hackaday logo, along with the numbers, is probably stored as a bitmap. I haven’t read the code so I dunno what “hackaday.com” is actually doing in there, maybe just filling up some bytes.

  6. CorrosiveOne says:

    wow.. that stabilized very very well :)

  7. Jimmy Bowler says:

    Looks cool. something you could try is to make it so it displays only the 12 and the hour number that it is.

    • Greenaum says:

      Presumably you can display anything you want on it, might be nice to have a button that cycles through a few display options, including your “minimalist” one.

      • Marius says:

        You are right about it. It is an ongoing project and I must make such a menu in order to first set the clock. I will control the entire menu using my IR remote control. Anyway, I’m planing to post further videos when this project will be completed.

  8. Krisztián says:

    Would it be possible to share the schematic which belongs to this project?
    I didn’t find it, just the layout “*.dip” in a compressed attachment.
    Thank you in advance.

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