I found out why the printer wasn't connecting. Some pins on the socket were bend an the Atmega didn't have a good connection. I still have one problem to solve. Even with these new stepper drivers Z-axis moves only down and it doesn't matter which way I command it to move. I guess I should check if there are more bend pins in the socket.
Edit: I was wrong. The Z-axis moves to both directions but they are swapped. Intreseting. I guess I should build and upload new firmware.
Edit: I was wrong. The Z-axis moves to both directions but they are swapped. Intreseting. I guess I should build and upload new firmware.