Wow,
I am speechless on the amount of work you have devoted to this. I think I may build it somewhere near what you just posted for 64 LEDs. I was thinking that I want to utilize a Wifi shield anyway because it allows me to isolate the globe such that the north pole is the 5v and the south pole is GND. The gnd would be through the motor’s shaft. Then I can have a UI to control it. In regards to your comment about H lagging due to programming each DAC, this was why I suggested putting a transistor on the common cathodes (one transistor per 24 channels) that would in unison allow the current to flow through the LED in unison. The voltage would be stabilized prior.
Revised:
Thank you for the work on this… greatly appreciated.
I think my plan for now is to do the 64 LED design. My question is in regards to your comment about H lagging due to programming each DAC, this was why I suggested putting a transistor on the common cathodes (one transistor per 24 channels) that would in unison allow the current to flow through the LED in unison. The voltage would be stabilized prior to allow for the variable current. I just need to develop an adequate design for the 0-120mA current of that LED.
I was thinking that I want to utilize a Wi-Fi shield anyway because it allows me to isolate the globe to simplify how it is mounted - the north pole is the 5v and the south pole is GND through the motor’s shaft. The UI for control would be thru the Wi-Fi shield.
I feel that I would not be able to use a standard Arduino as the primary MCU for memory allocation. I know I would just push new images bit by bit during its execution in such a way that it would update in a spiral fashion (top down on the globe). If I want to manipulate the current image, such as rotate it, I would just advance or retard the timing to image index. If I wanted to offset the globe on its axis, I doubt an Arduino could dynamical recompute the indexes for that and meet the timing requirements of everything else. I think a Maple could. In fact, there is enough I/Os ports on the Maple, that I may not need sub-processors. http://leaflabs.com/docs/hardware/maple.html
Thoughts?
V/R
Frank