Test four-wire stepper motor with Propeller QuickStart board and L298N stepper motor driver

README.md

Test four-wire stepper motor with Propeller QuickStart board and L298N stepper motor driver controller board.

Makefile

.PHONY: all clean

TARGET = test_stepper_motor

WRITE_TO_EEPROM ?= true

# See https://sites.google.com/site/propellergcc/documentation for details.
MEMORY_MODEL ?= lmm

BOARD = QUICKSTART

CC = /opt/parallax/bin/propeller-elf-gcc
CFLAGS = -m$(MEMORY_MODEL) -std=c99 -m32bit-doubles -O2
LOADER = /opt/parallax/bin/propeller-load
LFLAGS = -b $(BOARD)

all: $(TARGET)

$(TARGET):
	$(CC) $(CFLAGS) test_stepper_motor.c -o $@

load: $(TARGET)
ifeq ($(WRITE_TO_EEPROM),true)
	$(LOADER) $(LFLAGS) -e -r $<
else
	$(LOADER) $(LFLAGS) -r $<
endif

clean:
	-rm -f $(TARGET)

test_stepper_motor.c

#include <propeller.h>

#define FORWARD_BUTTON_ID  7
#define BACKWARD_BUTTON_ID 5

/* 4-wire stepper motor. */
#define MOTOR_COIL1_A_PIN 10  /* RGBY */
#define MOTOR_COIL1_B_PIN 11
#define MOTOR_COIL2_C_PIN 12
#define MOTOR_COIL2_D_PIN 13

#define NUM_STEPS_PER_REVOLUTION 200  /* 360 / 1.8 */
#define STEP_DELAY 3  /* 60 * 1000 / NUM_STEPS_PER_REVOLUTION / speed */

#define FORWARD 1
#define BACKWARD 0

#define PAUSE(time) waitcnt((time * (CLKFREQ / 1000)) + CNT)

#define SET_OUTPUT(pin, state)        \
  do {                                \
    if ((state) == 0) {               \
      _OUTA &= ~(1 << (pin));         \
    } else {                          \
      _OUTA |= 1 << (pin);            \
    }                                 \
  } while (0)

static volatile int step_id = 0;

void encode_step(char step) {
  switch (step) {
  case 0:  /* 1010 */
    OUTA |= 1 << (MOTOR_COIL1_A_PIN);
    OUTA &= ~(1 << (MOTOR_COIL1_B_PIN));
    OUTA |= 1 << (MOTOR_COIL2_C_PIN);
    OUTA &= ~(1 << (MOTOR_COIL2_D_PIN));
    break;
  case 1:  /* 0110 */
    OUTA &= ~(1 << (MOTOR_COIL1_A_PIN));
    OUTA |= 1 << (MOTOR_COIL1_B_PIN);
    OUTA |= 1 << (MOTOR_COIL2_C_PIN);
    OUTA &= ~(1 << (MOTOR_COIL2_D_PIN));
    break;
  case 2:  /* 0101 */
    OUTA &= ~(1 << (MOTOR_COIL1_A_PIN));
    OUTA |= 1 << (MOTOR_COIL1_B_PIN);
    OUTA &= ~(1 << (MOTOR_COIL2_C_PIN));
    OUTA |= 1 << (MOTOR_COIL2_D_PIN);
    break;
  case 3:  /* 1001 */
    OUTA |= 1 << (MOTOR_COIL1_A_PIN);
    OUTA &= ~(1 << (MOTOR_COIL1_B_PIN));
    OUTA &= ~(1 << (MOTOR_COIL2_C_PIN));
    OUTA |= 1 << (MOTOR_COIL2_D_PIN);
    break;
  }
}

void drive(char direction) {
  if (direction == FORWARD) {
    PAUSE(STEP_DELAY);
    if (step_id == NUM_STEPS_PER_REVOLUTION) {
      step_id = 0;
    }
    encode_step(++step_id & 3);
  } else {
    PAUSE(STEP_DELAY);
    if (step_id == 0) {
      step_id = NUM_STEPS_PER_REVOLUTION;
    }
    encode_step(--step_id & 3);
  }
}

int main() {
  int result;
  char pin;

  DIRA &= ~0xFF;  /* setup buttons */

  DIRA |= 1 << (MOTOR_COIL1_A_PIN);  /* setup motor */
  DIRA |= 1 << (MOTOR_COIL1_B_PIN);
  DIRA |= 1 << (MOTOR_COIL2_C_PIN);
  DIRA |= 1 << (MOTOR_COIL2_D_PIN);

  OUTA &= ~0xFF0000;  /* setup LEDs */
  DIRA |= 0xFF0000;

  OUTA |= 0xFF0000;  /* flash LEDs */
  PAUSE(1000);
  OUTA &= ~0xFF0000;

  while (1) {
    result = INA & (unsigned)(0xFF);
    for (pin = 0; pin < 16; pin++, result >>= 1) {
      SET_OUTPUT(pin + 16, result & 1UL);
      if (result & 1UL) {
        switch (pin) {
        case FORWARD_BUTTON_ID:
          drive(FORWARD);
          break;
        case BACKWARD_BUTTON_ID:
          drive(BACKWARD);
          break;
        }
      }
    }
  }
  
  return 0;
}