ESP-12e, Arduino IDE, NeoPixel Strip - Flickering
Have a google for (WS2812 or Neopixels) and ESP, it should give several good hints on how to wire it up reliably. Also really read this: https://learn.adafruit.com/adafruit-neopixel-uberguide/overview .

But some things to consider:


WS2812 requires 5V, so you do want to use a 5v source, not 3.3v.
Make sure all your grounds are connected together, especially if you have a separate power supply for the leds.
The data input on the WS2812 needs a 5v high signal, especially when the WS2812 is (correctly) powered by 5v. This means you probably need some kind of level shifter, which needs to be able to switch fast as well, cause it's a pretty high frequency signal.
224 WS2812's can chew up a lot of power, so make sure your 5v source can handle that. When all are set to full white, it's 20ma per color per led, that's 60ma per led, so 13,44 AMP maximum. Your average USB charger isn't gonna cope with that :) You can use a power supply which provides less power if you make sure you only turn on a few leds/colors at a time, but if you accidentially turn on more, voltage is gonna drop and stuff will stop working :)