The learning guide on Shifting Levels shows how to hook up a Feather to a Neopixel string using a TXB0108 level shifter. The example is powered with a 5 VDC supply for the Neopixels and a Lipo battery for the Feather.
I am building a fixed installation and want to eliminate the battery. Can I connect a 5VDC supply to the Feather via the USB pin and let the onboard voltage regulator furnish the 3.3V for the Feather and the level shifter?
Are any precautions required when I hook up a USB cable to upload software to the Feather?
Feather & Neopixel power options
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- dastels
- Posts: 15662
- Joined: Tue Oct 20, 2015 3:22 pm
Re: Feather & Neopixel power options
Yes, you can use the 3v pin (output from the Feather's regulator) to power the Feather side of the level shifter.
The bigger issue is supplying 5v via the USB pin. If you can use the USB connector to provide the 5v, that's the safer/easier choice. You just need a USB connector to match the Feather (with micro or C) which are available in the Adafruit shop (https://www.adafruit.com/product/1390, https://www.adafruit.com/product/1826, or https://www.adafruit.com/product/5180). That would require disconnecting the 5v and plugging in a USB cable to the computer for reprogramming. If you want to use the USB pin, you can, but you will need a diode to protect your 5v source when a USB cable is connected. Wire it with the cathode to the Feather's USB pin, and the anode to your 5v source.
Dave
The bigger issue is supplying 5v via the USB pin. If you can use the USB connector to provide the 5v, that's the safer/easier choice. You just need a USB connector to match the Feather (with micro or C) which are available in the Adafruit shop (https://www.adafruit.com/product/1390, https://www.adafruit.com/product/1826, or https://www.adafruit.com/product/5180). That would require disconnecting the 5v and plugging in a USB cable to the computer for reprogramming. If you want to use the USB pin, you can, but you will need a diode to protect your 5v source when a USB cable is connected. Wire it with the cathode to the Feather's USB pin, and the anode to your 5v source.
Dave
Please be positive and constructive with your questions and comments.