This firmware was first modified by Longer3D, based on Marlin 1.1.9 and applied to U20_Pro and U30_Pro. Marlin1.1.9 LGT0.3.X supports the U30 Pro / LK4 Pro printer by default. If you are using U20 Pro / LK5 Pro, you need unremark "U20_Pro" in Configuration.h.
Polamento added new changes in 2020 to enhance Marlin 1.1.9 in this printers, bringing new functions.
- Mesh bed leveling
- Calibrate extruder steps by screen
- Translation to Spanish
You MUST also install the screen software: