This project I have set aside for some time, I'm working on other projects that are more important currently. Ruibarbazul I see some differences in the pin assignments. I believe you are correct and what I posted is in error thanks. I have X one of the X pins going to PA not PB, which would make code very hard. hum that changes things. I dont have time to work on this project currently, maybe someone is working on STM32 GRBL and could help with coding for this board.