Have a look at Pololu’s design notes on the Fault Pin. https://www.pololu.com/product/2133 They Pololu DRV8825 has a pull-up resistor on the Fault pin and is fine with logic voltage as used on the A4988.

You have done a nice job with this board and the instructions. In looking at the schematic I have a concern when using the DRV8825 from Pololu.
The 8825 has a pin labeled nFAULT. This is an open drain output from the 8825. Your board has the pin tied to +5V. If the 8825 signals a fault will this not cause a short of the 5V power and potentially destroy the chip?

Thanks,
Ron Wensley

would be great with some insight. I find that making a UI on stm32f7 and attaching a grbl arduino nano to that would be a good compact solution.. if i could figure out how i would access the pins (thats why im tinkering with the idea of taking an existing arduino shield)

Would it be possible to run the CNC Shield on Due with the TinyG firmware? I’m thinking it should work, since you are really just extending the Arduino pins to the shield and incorporating the driver circuitry.

I’m complete noob in the Grbl word, but not in the Arduino one.
I am trying to connect a CDROM step motor, but can´t manage to have a smooth motion. Each time I send a command it moves but with a lot of hiccups, instead of a nice “ZZZZZZZZZ” noice, I get a “BrrZBrrZBrrZ”, and the motion is not clean.

I assume I might need some jumper somewhere and/or need to setup the Grbl with proper values.

Can anyone assist me?