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NodeMCU with 12V WS2811
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NodeMCU with 12V WS2811

by larrywal32 on Sat Aug 24, 2019 2:13 am

Hi - I have a 12V WS2811 neopixel strip - I have it hooked up and working properly with an Arduino Uno.

Now I am trying to swap the Arduino Uno for a NodeMCU and running into problems.

The uno setup is:
1. VIN - +12V
2. GND - ground
3. Pin 6 - Data

(I have a capacitor and resistor hooked in per Adafruit best practices)

....and all is fine.

FOR THE NODE MCU

My understanding is I have to level shift the data pin to 5V since the NodeMCU runs at 3.3V.

So I have a level shifter (using two external power supplies - one 3.3V and one 5V, essentially according to the schematic here (this schematic is for a 5V neopixel and mine is 12V): https://www.hackster.io/remnis/controll ... 266-0381c7)

See super rough (sorry I'm learning Fritz but bad with it) schematic attached - the lights sort of respond but are flashing super fast, wrong colors, etc...

I've got my multimeter out - what are good things to measure and report back on? Measuring voltage drop between A8 and B8 is about 0.8V (which is weird to me)....and it also makes the lights slightly flash differently.

All ideas welcome. I'm several hours in and no closer to figuring out the NodeMCU issue.
Attachments
schematic.png
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larrywal32
 
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Re: NodeMCU with 12V WS2811

by larrywal32 on Sat Aug 24, 2019 10:50 am

Couple other details:

- I was using an external supply board because the level shifter needs a 3.3V reference on vccb, and I don't have that.

- I tried making tying VCCA to the 7805 output, but it didn't change the weirdness I'm seeing. What was also odd is even when I had VCCA disconnected, the neopixel was still on and displaying funkiness

I'm attaching an updated schematic that clarifies two things - the "left side" of the schematic is powered from my benchtop power supply. The "right side" power supply board is powered from a wall outlet 9V plug.

I'm thinking maybe a reason for the badness is there isn't a common ground between them? Open to thoughts on that - although if that's the reason, I'm not sure how to get a common ground between them....

Lastly, this is the power supply board I'm using in case it helps: https://www.amazon.com/gp/product/B00HJ ... UTF8&psc=1

Thanks so much folks - can't say enough about how helpful this board is.
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schematicFull.png
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Re: NodeMCU with 12V WS2811

by franklin97355 on Sat Aug 24, 2019 2:33 pm

You should have a common ground connection between all of your devices.

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