Small POV Device Shows Off Some Big Features

We’ve already added the components needed to build [Rucalgary’s] tiny POV device to our next parts order. The little device sets a new standard for tiny persistence of vision boards. Instead of relying on the user to find the best speed and timing for swinging the board around, [Rucalgary] used an accelerometer. This is the point at which we’d usually groan because of the cost of accelerometers. We’re still groaning but this time it’s for a different reason.

The accelerometer used here is a Freescale MMA7660. It’s an i2c device at a super low cost of less than $1.50. The reason we’re still groaning is that it comes in a DFN-10 package that is a bit harder to solder than SOIC, but if you’ve got patience and a good iron it can be done. An ATmega48 drives the device, with 8 LEDs and one button for input. On the back of the board there’s a holder for a CR2032 coin cell battery and a female SIL pin header for programming the device.

Check out the video demonstration embedded after the break. We love it that the message spells and aligns correct no matter which way the little board is waved.


[Thanks Paul]

21 thoughts on “Small POV Device Shows Off Some Big Features

  1. That is pretty impressive, Love how he is all excited about how complete and ready to be pilfered his sources are. I wonder if it sports an OS hardware logo. Id say it is worthy of it.

  2. This is a really really nice build! Congratulations!

    One note though, I encourage you to practice your speech, it will be extremely useful in your future. Making more videos like this is one way to practice but having an interactive audience is way better. ;)

  3. We use a hotplate or a toaster oven for our MMA7660 breakout boards and it works really well. You want a temp-controlled hotplate, and set it at about 250. We have fiberglass plates on both sides of the hotplate so you don’t accidentally touch the heel of your hand against the plate while placing the chip. You can leave a little bead of solder on each pad with an iron, or use solder paste.
    Here’s our breakout board:

  4. Nice job. But HaD, c’mon – this has been sooo many times before! BTW I heard Dangerous Prototypes is developing a POV board with accelerometer. Is this the same project?

  5. @anfegori91, Drone: +10.

    My first thought was “this is old as dirt” too.

    I have no problem with the device, I have a problem with it being presented as anything else than ancient. And I can think of several progressively less kindly ways to say that.

  6. DFN is not hard to solder, just make sure you can access the traces that lead away from the IC with your iron. Simply with the solder down the trace to the IC – Make sure to use good flux. DFN devices can be done almost as easily as TSSOP devices.

  7. I had a theory of combining a PS3 Move controller and an addressable strip of LED’s (perhaps via a shift register) to make a fully controlled light saber, with PoV capabilities.

    Using the research on the PS3 Move controller previously shown on HaD (about a month or so ago), you have access to a 3 axis accelerometer, as well as additional movement sensors. The Move has a full colour LED, i.e. there are 3 pins available at the end of the controller to drive a shift register. And of course, it has a pretty capable STM32 microprocessor to do all the heavy lifting and calculation related to angles and acceleration and movement.

    I think that could be a very awesome repurposing of a PS3 Move controller, indeed!

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