Neopixel ring Clock with Flora and RTC

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samir_sogay
 
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Neopixel ring Clock with Flora and RTC

Post by samir_sogay »

I have made a Neopixel ring Clock with Arduino UNO (also tried with Micro) powered by 6600mAH battery and powerboost 500c. The run time of the clock even after sleep modes and low brightness is just close to a day. I have procured the Adafruit flora to replace the UNO and to power it directly via the 6600mAH 3.7V batteries hoping to increase run time. Is there a possibility that I can integrate the Neopixel ring (5V), RTC breakout (5V), Flora (3.3V) together even if all are operating at different voltages. If yes, could you tell me how. Or to power Flora with 1 battery and Neopixel and RTC via another battery then what about the Data signal voltages?

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adafruit_support_mike
 
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Re: Neopixel ring Clock with Flora and RTC

Post by adafruit_support_mike »

You can use multiple power sources in any circuit as long as you follow a couple of basic rules:

1) Connect the negative end of every power supply to the GND rail.

2) Never allow a low-resistance connection to exist between the positive ends of any two power supplies.

WRT #1: GND is the common reference point that everything in the circuit uses to measure voltages. Without that connection, a circuit taking power from supply A doesn't know how to measure voltages from a circuit taking power from supply B. That produces all kinds of confusing problems, ranging from signals that sometimes work and sometimes don't, to parts burning out.

WRT #2: Once you've connected the negative ends of two power supplies so they have a common reference voltage, connecting the positive ends is A Very Bad Idea. The one with higher voltage will try to pump current backwards through the one with lower voltage. At best that much power will be wasted, at worst something will short circuit and catch fire, and the most likely result is that one or both supplies will detect a serious problem and shut down to avoid catching fire.


To control 5v NeoPixels from a 3.3v Flora, you'll probably need a 'level shifter' between them.. a circuit that accepts 0v-3.3v as input and produces 0v-5v as output.

We know the 74AHCT125 works well for that: https://www.adafruit.com/product/1787

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