WS2812B Without SPI

Wed 2019.08.07

Hi @Gustav, I'm surprised at the frustration you must be going through as this shouldn't be that difficult. I have successfully driven three rows, two of those strings containing 60 Neopixels each. Rest assured, the MDBT42Q can handle what you are attempting.

'Im using pin D16 and D18'

Any of the GPIO pins will work. D16 and D18 are fine.

'Also cant seem to get the first LED lit up on either of the strips'

What is the result of using the code line in your #6 post? Replace the referenced pin with either of the above, and please explain what is seen.

'So once i write to 2 the API freezes'

Might be electrical noise on the data line, could be in the way code is sent to the pin. Bad data, Null data. Endless loop. Poorly constructed setInterval(). Could be if arrays are accessed that element zero is missed. Post some code here please.

Things to check:
Are the Neopixels and the MDBT42Q sharing a common ground?
What is the pin mode on each pin? getPinMode()
What is powering the MDBT42Q breakout board?
What is powering the Neopixels?
Do you 'actually' have Neopixels and not LED's as constantly referenced?
Logic Shifter could be an issue. Please post an image of it, datasheet and the wiring.

Has the datasheet been reviewed. There are many variants of Neopixel. If they were purchased from an offshore discount site, be aware that many claim to be selling WS2812B and in reality have one of these variants: Post an image of the Neopixel please.

REFERENCE table of RGB Led datasheets

Here is an example even using software SPI

WS2812b Neopixel and nRF52 chips

The onboard regulator is rated between 80-150ma. Attempting to power more than two individual Neopixels as @maze1980, points out, will most likely fry the regulator and possibly rendering the MDBT42Q a smoke detector tester.