LED Sphere project
hi!
i'm new arduino development , have been thinking of starting first own project after completing few exercise projects did starter kit & arduino uno. work on led sphere similar one:
http://www.youtube.com/watch?v=qrlr784qkeo
expect there multiple layers of sphere (~10 layers) accounting ~300 led's total sphere. i'm thinking of getting bunch of 5mm tri-color led's , tlc5940 shift registers drive led's. expect sphere rotate ~6000rpm (100rps) , diameter of sphere 25cm.
driving led's registers sounds simple in theory got bunch of questions feasibility of project:
1) based on led sphere specs seems need max update frequency of 15707hz of led's (100rps*25cm*pi/5mm). led's fast enough kind of update speed? read somewhere led's supposed have <1 microsecond on/off speed, mean 1mhz update speed , sounds sufficient me, verify this.
2) each led supposed have different level of brightness driven pwm of tlc5940 chip, has 12bit pwm control can run @ 30mhz (afaik), each led can updated @ 7342hz (30mhz/4096). possible change pwm control use less bits faster update (e.g. count 256, because data can have 256 level of brightness rgb anyway)?
3) can arduino control tlc5940 chips fast enough? ic's need update data @ ~16khz , there ~300 led's on sphere. each pwm control requires 12 bits of data rgb triplet , each bit of data takes @ least 3 cycles update (data setup + clock + clock down). means ~170mhz data update frequency (16khz*12*300*3) , ~500mhz pin update speed (170mhz*3). assuming serial data update of tlc5940 chips, parallelized using more pins, still arduino should able update data @ 500mhz, doesn't sound feasible considering 16mhz clock speed of arduino. since tlc5940 runs @ 30mhz, doesn't sound feasible. how should drive data chips instead?
thanks, jarkko
i'm new arduino development , have been thinking of starting first own project after completing few exercise projects did starter kit & arduino uno. work on led sphere similar one:
http://www.youtube.com/watch?v=qrlr784qkeo
expect there multiple layers of sphere (~10 layers) accounting ~300 led's total sphere. i'm thinking of getting bunch of 5mm tri-color led's , tlc5940 shift registers drive led's. expect sphere rotate ~6000rpm (100rps) , diameter of sphere 25cm.
driving led's registers sounds simple in theory got bunch of questions feasibility of project:
1) based on led sphere specs seems need max update frequency of 15707hz of led's (100rps*25cm*pi/5mm). led's fast enough kind of update speed? read somewhere led's supposed have <1 microsecond on/off speed, mean 1mhz update speed , sounds sufficient me, verify this.
2) each led supposed have different level of brightness driven pwm of tlc5940 chip, has 12bit pwm control can run @ 30mhz (afaik), each led can updated @ 7342hz (30mhz/4096). possible change pwm control use less bits faster update (e.g. count 256, because data can have 256 level of brightness rgb anyway)?
3) can arduino control tlc5940 chips fast enough? ic's need update data @ ~16khz , there ~300 led's on sphere. each pwm control requires 12 bits of data rgb triplet , each bit of data takes @ least 3 cycles update (data setup + clock + clock down). means ~170mhz data update frequency (16khz*12*300*3) , ~500mhz pin update speed (170mhz*3). assuming serial data update of tlc5940 chips, parallelized using more pins, still arduino should able update data @ 500mhz, doesn't sound feasible considering 16mhz clock speed of arduino. since tlc5940 runs @ 30mhz, doesn't sound feasible. how should drive data chips instead?
thanks, jarkko
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