One million dollar question.

Olin how do you balance the rotating board for each
eyeball ? :) Anything similar to tire balancing ?


WBR Dmitry.


Olin Lathrop wrote:
> 
> Lindy Mayfield wrote:
> > On Olin's page there is a cool spinning row of LEDs that show text.  In
> > this application, how does the PIC know the exact position of the
> > motor/row of led's?
> 
> There is an opto-interrupter mounted on the bottom of the rotating board,
> and a piece of metal sticking up from the stationary part the interrupts the
> beam once per rotation.  That pulse is captured with a CCP module on a
> 16C66, and the rest is all Firmware Magic (tm).
> 
> The one you see a picture of has 16 T1 3/4 LEDs vertically.  The new version
> has 96 RGB LEDs and can put up recognizable pictures of people's faces.  The
> data rates are rather higher as you can imagine, but the rotation tick is
> handled in pretty much the same way.  The new ball has 3 dsPICs and one 18F
> PIC.  One dsPIC runs the power supply, one does vector font to pixel
> rendering on the fly, and the third is on the rotary board moving the data
> around and driving the FPGA which does high speed updating of the LEDs
> including PWM to achieve 4 levels of brightness per pixel per color.
> 
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