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Dotstar with 3.3V boards in tutorial
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Dotstar with 3.3V boards in tutorial

by elin05 on Sat Dec 28, 2019 10:38 pm

The DotStar tutorial says they are 5V devices and may respond to 3.3V signals. And that logic level shifting is recommended. But this page shows it being used with 3.3V Feather M0 and Raspberry Pi without level shifters. Can it actually be used with those 3.3V boards without a level shifter?

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Re: Dotstar with 3.3V boards in tutorial

by adafruit_support_bill on Sun Dec 29, 2019 8:16 am

The device specifications call for a signal voltage level between 0.7VDD and VDD (VDD is the supply voltage). The 'nominal' voltage for VDD is listed as 5v. There is no minimum listed, but we have found that they run fine on 3.7V from LiPo cell.

If you are using 5v to power the pixels, the signal voltage according to the spec should be at least 0.7 * 5 = 3.5v. So 3.3v is close, but technically below spec. It may work, but it is not guaranteed.

If you power them with 3.7v from a LiPo, the minimum signal level is 2.59v, so 3.3v signals should work reliably.

https://cdn-learn.adafruit.com/assets/a ... 1574117503

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