3D printer RP2040 fan expansion board

This is a fan expansion board for a 3D printer. The initial motivation was that the mainboard I was using had too few controllable fan and servo motor channels, insufficient for my DIY needs. Furthermore, during initial wiring, a short circuit in the fan burned out an MKS Beast 8 mainboard. It was heartbreaking.
Therefore, I decided to make an expansion board (or rather, a sub-control board) to manage the fans, servos, and LED strips—devices prone to short circuits due to wiring issues. Even if a short circuit occurs again, it's likely only a fuse will burn out; in extreme cases, the sub-control board might be destroyed. The overall price is just over 20 yuan, compared to a main control board that often costs several hundred yuan. This distributed control is obviously lower in risk and repair cost. In addition, it increases DIY possibilities. Create your own unique printer!