Problems with the PWM signal on the SKR

[Squid]

@royag

I also tested the L and H connection of the power supply for the laser fire pin. The PWM is connected to the IN connection.

You need to connect only one wire from skr’s ground of the fet you’re using to L port on the LPSU. is that how you wired it? can you share the diagram showing how you connected the SKR to LaserPSU? also share your laser section in smoothie’s config file.

How to set up the SKR 1.3/1.4 Board with the K40 Laser

I don’t know how different laser power supplies are labeled and wired. i did this mod about a year ago so i am slow to remember what i did. yes - pin2.3 (Fan Fet) of my smoothie pulls-down L terminal of my laser power supply like so: [ice_screenshot_20201202-192255 - Copy] I guess you can chose to use pins 2.4, 2.5, or 2.7 the same way. i chose 2.3 as the fet is “quicker/faster” than the others and i thought it wont hurt thinking fast engraving and such but frankly - all are much faster t…