Mirroring X axis without GRBL

Projects General Guidance
1

Hello. I'm trying to use a CNC shield v3 for a robotics application. I would like to write my own code for now, using the AccelStepper library. Unfortunately, I can't seem to get the A axis to mirror the X axis.

My setup is as follows:
Arduino board: Arduino Uno Rev 3
Shield: CNC shield v3
Motors: NEMA17 (rated for 350mA)
Motor controllers: DRV8825 (Vref set to 0.17 V)
Power supply: 12V DC, 6A

The corresponding pins that mirror the A axis and the X axis are jumpered together.
The motor connected to the X axis moves on it's own just fine. The motor connected to the A axis doesn't move at all. I tried running the code below and also running it just with the commands for motorA.

The code I'm running as a test:

#include <AccelStepper.h>

// Voor de Arduino Uno + CNC shield V3
#define MOTOR_X_ENABLE_PIN 8
#define MOTOR_X_STEP_PIN 2
#define MOTOR_X_DIR_PIN 5

#define MOTOR_A_ENABLE_PIN 8
#define MOTOR_A_STEP_PIN 12
#define MOTOR_A_DIR_PIN 13

AccelStepper motorX(1, MOTOR_X_STEP_PIN, MOTOR_X_DIR_PIN);
AccelStepper motorA(1, MOTOR_A_STEP_PIN, MOTOR_A_DIR_PIN);

void setup()
{
   pinMode(MOTOR_X_ENABLE_PIN, OUTPUT);
   pinMode(MOTOR_A_ENABLE_PIN, OUTPUT);

   motorX.setEnablePin(MOTOR_X_ENABLE_PIN);
   motorX.setPinsInverted(false, false, true);
   motorX.setAcceleration(500);
   motorX.setMaxSpeed(2000);
   motorX.setSpeed(1000);
   motorX.enableOutputs();

   motorA.setEnablePin(MOTOR_X_ENABLE_PIN);
   motorA.setPinsInverted(false, false, true);
   motorA.setAcceleration(500);
   motorA.setMaxSpeed(2000);
   motorA.setSpeed(1000);
   motorA.enableOutputs();
}

void loop()
{
   motorX.move(3000);
   motorX.run();
   motorA.move(3000);
   motorA.run();
}
2

Hi @claim_7z ,

the code you posted cannot be the one that's running your test :wink:

motorA.setEnablePin(MOTOR_Z_ENABLE_PIN);

MOTOR_Z_ENABLE_PIN is not defined (but MOTOR_A_ENABLE_PIN !).

After correcting this your sketch runs on Wokwi: https://wokwi.com/projects/419975573394419713

Wokwi provides a A4988 driver board only but that should not be of importance as your motor X moves and motor A does not ...

What happens if you replace motor X by motor A? Does A work when wired to the DRV8825 board that is connected to pins 2 and 5?

3

You are correct, sorry! Code has been modified.

   motorA.setEnablePin(MOTOR_X_ENABLE_PIN);
   motorA.setPinsInverted(false, false, true);
   motorA.setAcceleration(500);
   motorA.setMaxSpeed(2000);
   motorA.setSpeed(1000);
   motorA.enableOutputs();

I also switched the motors around just in case something was faulty but the motors work ok. It's when I connect them to the A axis slot that the issues appear.

4

So both motors are stepping if wired to "X driver" but both don't when wired to the "A driver"?

5

Yup, that's correct.

6

Okay ... Now if you replace the "X driver" by the "A driver" do they still work?

If not, there must be something different with your "A driver" board ... :wink:

7

So I've done all combinations (switched around motors and motor drivers) and it turns out one of the motors had failed. Not entirely sure why - probably something I did while setting up, I'm still getting the hang of this.

The code works now, even managed to move stuff around. Have new problems now, but it's a step forward.

Thank you, @ec2021 !

8

You are welcome; sorry for the new problems

However, if it was easy what be the fun? :wink:

Good luck and success!
ec2021

9

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