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Feather and 5 neopixels
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Please be positive and constructive with your questions and comments.

Feather and 5 neopixels

by ltodd2 on Wed Dec 18, 2019 7:46 am

Hi all
I hope ive got the correct place for this question. Im wanting to run max 5 of the newer neopixels with the white led built in. Ive used them on arduino's before but thats a 5v board but im wanting to make this as small and light as possible and the option to have a plugin lipo to power it fits well with what im trying to build. My 2 questions are:
1. how would i run the pixels from the feather with it being 3.3 volt. have read they will just work but also read you need a level shifter but no clear answer.
2. With max 5 lights and the board what size battery would i need. for it to run for an hour and half would be good. I can get the led power data but cant find data on the feather

Thanks

Lee

ltodd2
 
Posts: 23
Joined: Mon Apr 06, 2015 12:14 pm

Re: Feather and 5 neopixels

by dastels on Wed Dec 18, 2019 7:04 pm

1. You should be fine powering the neopixels with 3.3v and driving them from a digital out pin. You only need a level shifter if you power them with 5v and are using 3.3 logic to drive them. I have a device with 48 neopixels running off an ItsyBitsy M4.

2. A lot depends on how the pixels are used. If they're white a lot of the time they're using a lot more power. Remember, for each of R, G, and B there's a completely separate LED. The more of the LEDs you have on, and the higher the value, the more power the pixel consumes. Worst case (full brightness white) they'll draw ~60mA. If you have RGBW pixels, white is a single LED. Here's the info on powering the pixels and computing current needs: https://learn.adafruit.com/adafruit-neopixel-uberguide/powering-neopixels.

Different feathers will have different power requirements, ones with radios take more. Larger MCUs take more, etc. Figure a max of 500mA since that's what the on board regulator caps out. It's usually be far less.... depending on what other hardware is being powered.

My rule of thumb: use the biggest LiPo that will fit. Then use the device in typical ways and measure how long it lasts. If it's a lot longer than you need, you can try a smaller battery. It's a bit of black magic IMO.

Dave

dastels
 
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Re: Feather and 5 neopixels

by ltodd2 on Thu Dec 19, 2019 5:19 am

Hi Dave
Thanks for the reply. Since posting this ive looked at a lot of other controllers with the latest being the ATTiny. All I will be doing it having 3 or 5 pixels. in the case of 3 is will be one red, one green and using the white to flash all 3 every second. Or i will double the red and green so 5 in total. Im wanting to put it on a drone, plane etc so size and weight is the biggest issue hence why wanting the smallest controller. the feather I liked for the inbuilt lipo charger but the attiny can be made very small but no charger and a pain to program.

Think i may been to get a few different controllers and see.

Thanks

Lee

ltodd2
 
Posts: 23
Joined: Mon Apr 06, 2015 12:14 pm

Re: Feather and 5 neopixels

by dastels on Thu Dec 19, 2019 10:52 am

A TrinketM0 might work well for you. The older ones don't work so well in a modern USB world and will likely end up just being frustrating. It doesn't have a charger on board, but you can use https://www.adafruit.com/product/2124. You can't mount it directly on the TrinketM0, but it's just 3 wires.

Dave

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Re: Feather and 5 neopixels

by ltodd2 on Thu Dec 19, 2019 12:35 pm

Thanks again Dave

I had seen this charger and was going to ask if it will work with the M0. I had worked out it would not fit the same already. Also the usb issue with the original was concerning me. Think i will get the M0 and the charger and give it ago. I might even get the attiny aswell as im guessing i could still use the charge board to deal with the battery. Ive got a few arduino I can use as a programmer for it (Once ive read how :))

Thanks

Lee

ltodd2
 
Posts: 23
Joined: Mon Apr 06, 2015 12:14 pm

Re: Feather and 5 neopixels

by dastels on Thu Dec 19, 2019 1:31 pm

Yes, the charger board just needs USB voltage, ground, and battery input (to the controller).

dastels
 
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Re: Feather and 5 neopixels

by ltodd2 on Mon Dec 23, 2019 10:29 am

Hi Dave

Whats the difference if any with the 2124 and 1904? All i can see is the 2124 is .7g lighter :)

Thanks

Lee

ltodd2
 
Posts: 23
Joined: Mon Apr 06, 2015 12:14 pm

Re: Feather and 5 neopixels

by dastels on Mon Dec 23, 2019 10:57 am

1904 is meant to be a standalone charger, so it has a USB jack. Apart from the physical connections, the circuit is the same. The backpack would be lighter since it doesn't have the USB connector and the board is a bit smaller.

Dave

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Re: Feather and 5 neopixels

by ltodd2 on Mon Dec 23, 2019 12:40 pm

Thanks Dave
Merry Christmas

Lee

ltodd2
 
Posts: 23
Joined: Mon Apr 06, 2015 12:14 pm

Please be positive and constructive with your questions and comments.