Adding LEDs for lighting, on the RAMPS 1.4

What would be a good approach to add some LED strips for lighting purposes (mounted onto the X carriage) using the RAMPS 1.4 and Marlin?

I need something I can turn on and off with gcodes.

I use a custom fan controller connected to a series of LEDs I've hot glued to the bottom of my x-carriage. M42 is the g-code to turn the selected pin on and off, or optionally if you're using a PWM port, to what value you want the pin to be at (0-255). You likely will get a flicker when the heated bed or extruder reach temperature as the high current loads rapidly turn on and off. You can either use a constant current driver or run a separate voltage regulator to smooth out the flicker.

The original idea was for a fan, but I don't see any reason you could not use it for a couple of leds. Just check your current ratings first.

[www.thingiverse.com]

Have fun, good luck

I was actually trying to add a led that gets on whenever the head bad is above X degrees.

Marlin has a setting to turn on a pin (normally to control a fan) when the hot end temperature reaches a configured temperature. You'd have to tweak it to look at the bed temp instead of hot end, but you could use that to turn on an pin to show a status LED.

Ok, I'll explore that, most likely it will requite some custom code.
Thanks!