I add header for NUCLEO with this design decision:
- 24V-5V step-down power supply, based on MCP16301
- all 6 axis buffered with 74HCT541D and wire with shielded RJ45 connector -additional 9 output opto-isolated NPN
- 15 input also opto-isolated
- nice push-in wago 254 connection
because of not isolated power supply I decide to leave ground connected so there is possibility to destroy something, but risk is much lower than without opto-isolation.
Software based on https://github.com/Schildkroet/GRBL-Advanced
Software modification are simple:- change pin mapping for better pcb routing
- enable all axis
- enable external memory
- add some additional commands for GPIO debugging (show state of input)