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Trinket 5v with dotstar LED's help
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Trinket 5v with dotstar LED's help

by charlzahk on Thu Apr 23, 2020 8:23 pm

The trinket seems to not power dotstar led strips with over 100 leds. I've tried powering from the 5v and USB pinout. They seem to work when I lower the number of pixels in the code. I've also tried lowering the brightness which doesn't seem to help.

I'm trying to make a LED smart hula hoop. I need 150 leds ideally. Is there any way to make it work?

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Re: Trinket 5v with dotstar LED's help

by dastels on Thu Apr 23, 2020 9:16 pm

First, there's power. 150 DotStars will require up to 9A. That's worst case with them all white at full brightness, but even using just one of the LEDs (say just red) in each at half brightness would need about 1.5A.

The other issue is memory. The ATtiny85 on the Trinket only has 512 bytes of RAM and if each DotStar needs just 3 bytes, 150 will need 450 bytes. That's pretty tight... only 62 bytes left for anything else.

Switching to a Trinket M0 will solve the memory limitations, but there's still power, and you'll need a level shifter to drive that many, as mentioned at the bottom of https://learn.adafruit.com/adafruit-dotstar-leds/power-and-connections.

Dave

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