Arduino ProMini car project ws2812b

[jipaionutcatalin]

Hi all
I have this project in mind, rear signal light and brake to a ws2812b 12 led strip, 6 for a left signal turn yellow, 6 for a right turn yellow and 12 red led when brake. Because it is at the rear I need to take the 'signal' for my mini pro Arduino i/o pins from the light itself which will be 12 v. What I need to use to convert the ground and positive 12 v to a signal input for the pro mini?. Thanks in advance.

[tmadness]

A simple voltage divider should be enough, but automotive 12 v tends to be dirty with spikes >> 12 V so you can feed the reduced voltage through a optocoupler.  You could add a few clamping diodes to further mitigate those nasty spikes.
something like this should work, https://www.vishay.com/docs/84433/voma617a.pdf . But there are probably dozens of alternatives.

[jipaionutcatalin]

Thx for that.

[mikerj]

What are you going to do when braking and indicating?  Turn signal spacing on a strip of 12 LEDs will not be legal in the UK.

[jackthomson43]

You can use simple relay boards or FETs i.e. 75N75. It will be placed in between Arduino Pro Mini & ws2812b and using FET you can easily control 12V LEDs with 5V logic. Read it out. How to use FETs as a switch.

Btw in your case simple NPN transistor i.e. BC547 will also work as ws2812b doesn't need much amperes.