Arduino based plotter motherboard copy

The code source comes from the open source project grbl. The arduino nano-based main control board is drawn according to grbl and supports laser pwm, servos and electromagnets. There are many finished motherboards on the market for lasers and servos, but there are no motherboards for electromagnet direct drive. Anyone who likes writing machines knows that although the servo is good for lifting the pen, it makes too much noise. Stepping up the pen depends on a high-cost pen holder. Electromagnets are a good choice, but there is no one on the market that can directly drive the electromagnet. If you want to play with electromagnets on a motherboard, you can only add a relay to drive it directly. However, if you drive the electromagnet directly in this way, the current of the electromagnet will continue to be at the peak value, and it will soon fail or even be damaged due to overheating. My motherboard can not only directly drive the electromagnet, Cooperating with the drive circuit, it can reduce the drive current passing through the electromagnet for a long time, which will shorten the life of the electromagnet.