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gnea / grbl-Mega

An open source, embedded, high performance g-code-parser and CNC milling controller written in optimized C that will run on an Arduino Mega2560
https://github.com/gnea/grbl/wiki
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grbl-Mega on MKS BASE 1.6 board #105

Open scmaher opened 5 years ago

scmaher commented 5 years ago

I am using grbl on the MKS BASE 1.6 board. It is basically an arduino mega combined with a RAMPS 1.4 on a single board. Currently available for around $30 (with 5 A4982 drivers installed), so its pretty attractive.

The first problem I encountered was that the microstepping settings were different for the various axis. On the RAMPS 1.4 board these settings are controlled via jumpers. On the MKS BASE board, the MS1 and MS2 pins on the A4982 drivers are routed to pins on the atmega mpu:

              atmega pin

X MS1 PE2 (4) MS2 PH3 (15)

Y MS1 PF5 (92) MS2 PF4 (93)

Z MS1 PA0 (78) MS2 PG2 (70)

E0 MS1 PK1 (88) MS2 PK2 (87)

E1 MS1 PF3 (94) MS2 PG5 (1)

As far as I can tell, these pins are not initialized anywhere in the grbl code. Its not reasonable to expect grbl to account for every variation of board in the world. I've added some code to steppers.c to initialize these pins as outputs and set them to the correct state during the rest of the stepper initialization.

However, this doesn't seem like a very sustainable solution, as I'd like to be able to easily take updates as they become available. I know that I can add custom board definitions to the various .h files, but where should I locate board-specific code?

The second issue isn't really an issue, just a note for others who might be struggling with the problem. The MKS BASE 1.6 board has limit switch inputs for both min and max limits for x, y, and z axis. However, grbl reports only a single pin state variable for each axis. If you define the limit switches to be active high (a positive voltage on the limit pin indicates that that limit switch has been activated), any unconnected limit switch inputs can mask the connected input.

As an example, I have a X- (minimum) limit switch, but no X+ limit switch. Since grbl reports only one pin state for X axis limit switches, it always reports "active" for the X axis, regardless of the state of the X- limit switch.

The solution to this is simple, I just added a jumper between the limit pin and ground (conveniently located next to each other on the board I am using) for each limit switch input I am not using.

GRBL is an outstanding project, I've been using it since the early releases!

Steve

alexc57 commented 1 year ago

can you share your code please, I am on mks base v1.6 . thks and best regards