Adafruit dotstars

MichaelMeissner

MichaelMeissner

Senior Member+
I see that Adafruit has released an entirely new lighting technology (dotstars) that uses a 2 wire SPI protocol. This protocol does not have the strict 800Khz transmission link that neopixels/WS2812B's had, and I presume is friendlier for programs that use interrupts, and is better for POV projects. I would imagine the tricks that the ws2811/fastled libraries use would be applicable to dotstars as well, but I imagine it is probably very low on the priority queue and it would be an enormous amount of effort to do the ports. I do wonder if the Teensy might run so fast with these optimizations, that artificial delays might be needed, or if the lights can keep up with anything that the Teensy can throw. https://www.adafruit.com/product/2241.
 
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Adafruit basically invented a new name for the existing APA102 leds. FastLED supports them since june 2014...

Daniel drove short strips already with >20 MHz clock speed.
 
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I figured it was a new name for an existing technology. Thanks. Though hopefully those that run lights that fast take care to warn sensitive people whom get epileptic seizures with fast blinking lights.
 
This site claims "Between 3-30 hertz (flashes per second) are the common rates to trigger seizures".

This other one is more specific, claiming "A flash at a frequency of between 15 and 20 flashes per second is most likely to cause a seizure, whereas very few people are sensitive to a rate of 3 flashes per second".

I'd imagine duty cycle probably also plays a factor, since nearly all movie theaters flash a huge screen at 24 Hz, but they minimize the dark time.

It seems pretty safe to say humans aren't very sensitive to dramatically higher speeds, like 430 Hz in WS2812 and 20 kHz in APA102.
 
traditional movie film cameras are 24 frames/sec. As I recall, this rate was chosen to be the lowest practical given the human persistence of vision. Higher film frame rates add cost for more film.

In sets where there are Television screens (not 24fps), there are specially configured film cameras to synch to TV vertical intervals to avoid flicker. I have a friend who did this for the studios for many years.
 
In case anyone is tempted to order them from Adafruit, they are 74$/m at adafruit for the 144led/m version and the same is 20$ at ray wu on aliexpress... I really like Adafruit but that seems like a huge markup...
 
Cheers for the pointer to a cheaper supplier. I'm really looking forward to playing with the APA102 strips (plus Teensy plus FastLED).
 
http://www.aliexpress.com/item/1m-D...LED-M-144pixels-WHITE-PCB-in/32244460348.html not so expensive.

In case anyone is tempted to order them from Adafruit, they are 74$/m at adafruit for the 144led/m version and the same is 20$ at ray wu on aliexpress... I really like Adafruit but that seems like a huge markup...
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the new york office and employee salaries would cost them a lot...

adafruit have the art to make you waste time and money with their "fancy cool product naming".
 
Linda-sfleds said:
I made a demo video with teensy source code ....
APA102 is good for us because we can call FastLED with free timing, so we can wait to read all serial port data before calling fastLED again :)
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Can you explain how you used Teensy or FastLED?

These messages look like spam. I'm going to delete the links. If you really are here to talk about designing projects, rather than post ads for LEDs, now is the time speak up and convince us you're a real, genuine person.
 
@paul, this is spam, post #10 has exactly the same wording as post and link to video as user mabeghin on another apa102 thread https://forum.pjrc.com/threads/2692...table-for-POV-installations?p=89013#post89013
post number 4. user has follow up post adding some small technical element. no other posts by that user. I have marked it as spam, so it may disappear.

EDIT: post #4 is now deleted, so there is a new post #4, which was the old post #5, that is not spam. If you get me...
 
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Ok, spam it is. Since they went to the trouble to try mentioning Teensy and FastLED, I was curious if a real person would reply. But no...
 
FWIW, I am working on a clock with APA102s. But it's been waiting for several months due to higher priority items...
 
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