Mechanical Design, Machine Design

Note: The connector going directly into the stepper motor has 6 wires, but the output connecting to the board uses only 4 pins.

Note: Zero-ohm resistors can help when you have no idea how to route a trace, but it is not considered good practice.

Note: The drivers are flipped so they can be soldered from the bottom.

"Flip" Technique for Through-hole Components

To make soldering easier on a single-sided board, I placed the female pins (for drivers and MCU) on the back side. This allows the pins to pass through the board to be soldered comfortably on the copper side.

Design Note: This must be done before routing, as flipping creates a mirror effect on the pin layout.

#include <AccelStepper.h>

// =========================
// Motor 1 Pins
// =========================
#define STEP_PIN_1    D0
#define DIR_PIN_1     D1
#define ENABLE_PIN_1  D2

// =========================
// Motor 2 Pins
// =========================
#define STEP_PIN_2    D3
#define DIR_PIN_2     D4
#define ENABLE_PIN_2  D5

// =========================
// Motor 3 Pins
// =========================
#define STEP_PIN_3    D8
#define DIR_PIN_3     D7
#define ENABLE_PIN_3  D9

// =========================
// Motor 4 Pins (NEW)
// =========================
#define STEP_PIN_4    D10  // Change these pins according to your board
#define DIR_PIN_4     D11
#define ENABLE_PIN_4  D12

// =========================
// Motor Configuration
// =========================
#define FULL_STEPS_PER_REV 200
#define MICROSTEP          1

const long TEST_STEPS = FULL_STEPS_PER_REV * MICROSTEP;
const float MAX_SPEED  = 1000.0;
const float ACCEL      = 2000.0;
const float CONT_SPEED = 750.0;

// ── Four AccelStepper instances ───────────────────────────────────────
AccelStepper stepper1(AccelStepper::DRIVER, STEP_PIN_1, DIR_PIN_1);
AccelStepper stepper2(AccelStepper::DRIVER, STEP_PIN_2, DIR_PIN_2);
AccelStepper stepper3(AccelStepper::DRIVER, STEP_PIN_3, DIR_PIN_3);
AccelStepper stepper4(AccelStepper::DRIVER, STEP_PIN_4, DIR_PIN_4);

bool continuousMode = false;

// ── Enable / disable all four drivers at once ─────────────────────
void enableDrivers(bool enable)
{
  digitalWrite(ENABLE_PIN_1, enable ? LOW : HIGH);
  digitalWrite(ENABLE_PIN_2, enable ? LOW : HIGH);
  digitalWrite(ENABLE_PIN_3, enable ? LOW : HIGH);
  digitalWrite(ENABLE_PIN_4, enable ? LOW : HIGH);
}

void setup()
{
  Serial.begin(115200);
  pinMode(ENABLE_PIN_1, OUTPUT);
  pinMode(ENABLE_PIN_2, OUTPUT);
  pinMode(ENABLE_PIN_3, OUTPUT);
  pinMode(ENABLE_PIN_4, OUTPUT);
  enableDrivers(true);

  // ── Configure all four motors with the same parameters ──────────────
  stepper1.setMaxSpeed(MAX_SPEED);
  stepper1.setAcceleration(ACCEL);
  stepper2.setMaxSpeed(MAX_SPEED);
  stepper2.setAcceleration(ACCEL);
  stepper3.setMaxSpeed(MAX_SPEED);
  stepper3.setAcceleration(ACCEL);
  stepper4.setMaxSpeed(MAX_SPEED);
  stepper4.setAcceleration(ACCEL);

  Serial.println("DRV8825 + AccelStepper Test (4 motors)");
  Serial.println("Commands:");
  Serial.println("  1 -> one revolution direction 1");
  Serial.println("  2 -> one revolution direction 2");
  Serial.println("  3 -> continuous rotation direction 1");
  Serial.println("  4 -> continuous rotation direction 2");
  Serial.println("  0 -> stop");
}

void loop()
{
  if (Serial.available())
  {
    char cmd = Serial.read();
    switch (cmd)
    {
      case '1':
        continuousMode = false;
        stepper1.moveTo(stepper1.currentPosition() + TEST_STEPS);
        stepper2.moveTo(stepper2.currentPosition() + TEST_STEPS);
        stepper3.moveTo(stepper3.currentPosition() + TEST_STEPS);
        stepper4.moveTo(stepper4.currentPosition() + TEST_STEPS);
        Serial.println("One revolution direction 1 (4 motors)");
        break;

      case '2':
        continuousMode = false;
        stepper1.moveTo(stepper1.currentPosition() - TEST_STEPS);
        stepper2.moveTo(stepper2.currentPosition() - TEST_STEPS);
        stepper3.moveTo(stepper3.currentPosition() - TEST_STEPS);
        stepper4.moveTo(stepper4.currentPosition() - TEST_STEPS);
        Serial.println("One revolution direction 2 (4 motors)");
        break;

      case '3':
        continuousMode = true;
        stepper1.setSpeed(CONT_SPEED);
        stepper2.setSpeed(CONT_SPEED);
        stepper3.setSpeed(CONT_SPEED);
        stepper4.setSpeed(CONT_SPEED);
        Serial.println("Continuous rotation direction 1 (4 motors)");
        break;

      case '4':
        continuousMode = true;
        stepper1.setSpeed(-CONT_SPEED);
        stepper2.setSpeed(-CONT_SPEED);
        stepper3.setSpeed(-CONT_SPEED);
        stepper4.setSpeed(-CONT_SPEED);
        Serial.println("Continuous rotation direction 2 (4 motors)");
        break;

      case '0':
        continuousMode = false;
        stepper1.setSpeed(0);
        stepper1.moveTo(stepper1.currentPosition());
        stepper2.setSpeed(0);
        stepper2.moveTo(stepper2.currentPosition());
        stepper3.setSpeed(0);
        stepper3.moveTo(stepper3.currentPosition());
        stepper4.setSpeed(0);
        stepper4.moveTo(stepper4.currentPosition());
        Serial.println("Stop");
        break;
    }
  }

  // ── Run all four motors on each cycle ───────────
  if (continuousMode)
  {
    stepper1.runSpeed();
    stepper2.runSpeed();
    stepper3.runSpeed();
    stepper4.runSpeed();
  }
  else
  {
    stepper1.run();
    stepper2.run();
    stepper3.run();
    stepper4.run();
  }
}