CNC Pen Plotter Help Required

Projects General Guidance
1

Greetings,

I am very new to arduino and microcontrollers in general.

I am building a cnc pen plotter using:

-MEGA 2560 R3 Board
-2x 28BYJ-48 Stepper Motors
-2x ULN2003 Stepper Motor Driver Board
-1x SG90 Servo Motor

Ive already got the mechanical frame setup.

I have installed this GitHub - 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 GRBL Library on my MEGA Board, and it is recognized in "Universal Gcode Sender".

I can send files to it and the process runs, however none of my motors or servo get activated. Also no "Machine Status"

My question:

Where can i setup the correct pins for the motors?

Is this even possible with ULN2003?

Thanks in advance

2

Google will show you many on line tutorials describing how to use that stepper with Arduino.

For informed help, please read and follow the directions in the "How to use this forum" post.

3

I suspect that GRBL does not work with ULN2003 stepper drivers. AFAIK it is designed for the the sort of stepper motor driver that takes step and direction signals.

...R

4

A couple of A4988 modules can probably be pressed into service if you can modify the 28BYJ-48's to
4-wire (I think I've seen articles about doing this - have a search)

GRBL doesn't have enough output pins or free processor cycles to drive anything but step/direction
stepper drivers. Such drivers require bipolar stepper motors (not 5 wire).

Having said that some one somewhere might have hacked GRBL or something similar (normally GRBL
has to handle 3 sets of limit switches, 3 steppers and a spindle motor, which is why it doesn't
come with spare pins for unipolar).

5

I found a GRBL hack for 328p boards so i used my Nano for it.

This seems to work.

Now i just have to setup the right parameters such as workspace size etc.

6

krakc:
I found a GRBL hack for 328p boards so i used my Nano for it.

Please post a link to it for the benefit of other readers.

...R

7

The official version 1.1 of grbl is for 328 processors only.

From the version 1.1 cpu_map.h file.

/* The cpu_map.h files serve as a central pin mapping selection file for different
processor types or alternative pin layouts. This version of Grbl officially supports
only the Arduino Mega328p. */

8

I suspect that the hack the OP found is for a 28BYJ stepper motor - we will see if and when he posts a link to it.

...R

9

It is for the 28BYJ stepper motor:

Setup:

The schematic has a ULN2003 Driver.

The servo portion (z-axis) doesnt work however. this needs to be manually changed in the code or by using a post processor for editing the gcode files. I will be trying to change the code.

10

its work?
http://www.glan.com.br/Nerduino_004_Arduino_007.html