Arduino uno + cnc shield v3 + Stepper Motor Driver A4988 + AccelStepper?

Question

I successfully run the AccelStepper examples on an Arduino Mega with a RAMPS 1.4 shield, two A4988 stepper motor drivers and two 17HS16-0284S stepper motors.

I used 3 jumpers on the RAMPS to set the microstep resolution to 1/16.

I used this code inspired by the Polargraph Server for Polargraph:

#include <AccelStepper.h>

/* 
// for the Arduino Uno + CNC shield V3

#define MOTOR_A_ENABLE_PIN 8
#define MOTOR_A_STEP_PIN 2
#define MOTOR_A_DIR_PIN 5

#define MOTOR_B_ENABLE_PIN 8
#define MOTOR_B_STEP_PIN 3
#define MOTOR_B_DIR_PIN 6
*/

// for the Arduino Mega + RAMPS 1.4
#define MOTOR_A_ENABLE_PIN 30
#define MOTOR_A_STEP_PIN 36
#define MOTOR_A_DIR_PIN 34

#define MOTOR_B_ENABLE_PIN 56
#define MOTOR_B_STEP_PIN 60
#define MOTOR_B_DIR_PIN 61

AccelStepper motorA(1, MOTOR_A_STEP_PIN, MOTOR_A_DIR_PIN); 
AccelStepper motorB(1, MOTOR_B_STEP_PIN, MOTOR_B_DIR_PIN); 

void setup()
{
  motorA.setEnablePin(MOTOR_A_ENABLE_PIN);
  motorA.setPinsInverted(false, false, true);
  motorB.setEnablePin(MOTOR_B_ENABLE_PIN);
  motorB.setPinsInverted(false, false, true);

  motorA.setAcceleration(100);  
  motorA.move(1000);
  //motorA.setMaxSpeed(100);
  //motorA.setSpeed(100);

  motorB.setAcceleration(100);  
  motorB.move(1000);
  //motorB.setMaxSpeed(100);
  //motorB.setSpeed(100);

  motorA.enableOutputs();
  motorB.enableOutputs();
}

void loop()
{

  motorA.run();
  motorB.run();

}

I tried to use the same code with the same stepper motor drivers and motors on a Arduino Uno and a CNC shield v3 without success (I also used the 3 jumpers to set the microstep resolution to 1/16). The motors do not work and jitter.

What is wrong with my code?

Bonus questions: I have taken this setup and code from the Polargraph server but I didn't get how I'm suppose to know how to use setEnablePin() and setPinsInverted() methods. In fact, I have troubles finding documentation about the CNC shield V3 and the A4988 drivers (I only found this page) to work with AccelStepper.

Answer 1

Manually set the ENABLE pins as OUTPUTs, i.e. add in the setup() function:

pinMode(MOTOR_A_ENABLE_PIN, OUTPUT);
pinMode(MOTOR_B_ENABLE_PIN, OUTPUT);