[gnea/grbl-Mega Issue#107] not working with mega2560 + cnc shield v3

#1 – chamnit 于 2019-07-19

Grbl on Mega has a different pin configuration that isn’t compatible with Arduino Uno shields. See the wiki for the pin outs and you’ll have to find a way to connect them correctly.

#2 – drf5n 于 2022-03-13

Oh my– it is very different. The CNC Shield V3 schematic from https://blog.protoneer.co.nz/arduino-cnc-shield/ has the step pins to the Mega’s 2,3,4, which are PE4,PE5,PG5, which aren’t on the same port, etc… The definitions in https://github.com/gnea/grbl-Mega/blob/df87b36f48b90930714accf03b411b60d5d948e5/grbl/cpu_map.h#L29 map those pins to Port A, PA2,PA3, PA4 on the Arduino Mega’s pins 24,25,26, etc …

It looks like one could use the V3 shield’s double-row of connectors for XSTEP/DIR…ASTEP/DIR with jumpers to the MEGA’s extended pins. grbl doesn’t do 4 axes of steppers, so it’s these 9 wires up to the CNC Shield V3 for control:

Mega 13 >> EN | GND
Mega 24 >> XSTEP | XDIR << Mega 30 Mega 25 >> YSTEP | YDIR << Mega 31 Mega 26 >> ZSTEP | ZDIR << Mega 32 ASTEP | ADIR Mega 5V >> 5V | GND << Mega GND Then bypass the board and hook your X,Y,Z stops up as 10,11,12; and RESET, HOLD, RESUME, DOOR as A8,A9, A10,A11, and the spindle EN,DIR as 6,7, and the coolant Flood/Mist as 8,9. The CNC Shield V3 won't work neatly attached to the Arduino Mega as it does to the Uno https://github.com/gnea/grbl/wiki/Connecting-Grbl It might be nice do do an image like https://github.com/gnea/gnea-Media/raw/master/Grbl%20Help/GrblPinDiagram_v0.9+.png?raw=true for the Mega2560.