Stepper motor on BeagleBone Blue

README.md

Parts

• Motor
• Wires
• Crimp headers
• Housing

Tools

• Soldering iron
• Exacto knife

Modified unipolar stepper to bipolar

I followed a blog article on how to modify this unipolar stepper to be bipolar, because BeagleBone Blue has built-in H-bridges

Wiring

I used an EduMIP, which has DC motors on M2 and M3, so I grabbed M1 and M4.

I used a wiring housing to line up the wires to the stepper motor header.

• M1+: Pink (2)
• M1-: Orange (4)
• M4+: Yellow (3)
• M4-: Blue (1)
• center-tap (unused): Red (5)

Software

git clone https://gist.github.com/jadonk/1da9f20423c2e6c8a954eca1a3e8f7f2
cd 1da9f20423c2e6c8a954eca1a3e8f7f2
make
./stepper_example

IMG_1160.JPG

IMG_1161.JPG

IMG_1162.JPG

Makefile

# This is a general use makefile for librobotcontrol projects written in C.
# Just change the target name to match your main source code filename.
TARGET = stepper_example

# compiler and linker binaries
CC		:= gcc
LINKER		:= gcc

# compiler and linker flags
WFLAGS		:= -Wall -Wextra -Werror=float-equal -Wuninitialized -Wunused-variable -Wdouble-promotion
CFLAGS		:= -g -c -Wall
LDFLAGS		:= -pthread -lm -lrt -l:librobotcontrol.so.1

SOURCES		:= $(wildcard *.c)
INCLUDES	:= $(wildcard *.h)
OBJECTS		:= $(SOURCES:$%.c=$%.o)

prefix		:= /usr/local
RM		:= rm -f
INSTALL		:= install -m 4755
INSTALLDIR	:= install -d -m 755

SYMLINK		:= ln -s -f
SYMLINKDIR	:= /etc/robotcontrol
SYMLINKNAME	:= link_to_startup_program


# linking Objects
$(TARGET): $(OBJECTS)
	@$(LINKER) -o $@ $(OBJECTS) $(LDFLAGS)
	@echo "Made: $@"


# compiling command
$(OBJECTS): %.o : %.c $(INCLUDES)
	@$(CC) $(CFLAGS) $(WFLAGS) $(DEBUGFLAG) $< -o $@
	@echo "Compiled: $@"

all:	$(TARGET)

debug:
	$(MAKE) $(MAKEFILE) DEBUGFLAG="-g -D DEBUG"
	@echo " "
	@echo "$(TARGET) Make Debug Complete"
	@echo " "

install:
	@$(MAKE) --no-print-directory
	@$(INSTALLDIR) $(DESTDIR)$(prefix)/bin
	@$(INSTALL) $(TARGET) $(DESTDIR)$(prefix)/bin
	@echo "$(TARGET) Install Complete"

clean:
	@$(RM) $(OBJECTS)
	@$(RM) $(TARGET)
	@echo "$(TARGET) Clean Complete"

uninstall:
	@$(RM) $(DESTDIR)$(prefix)/bin/$(TARGET)
	@echo "$(TARGET) Uninstall Complete"

runonboot:
	@$(MAKE) install --no-print-directory
	@$(SYMLINK) $(DESTDIR)$(prefix)/bin/$(TARGET) $(SYMLINKDIR)/$(SYMLINKNAME)
	@echo "$(TARGET) Set to Run on Boot"

stepper_example.c

/**
 * @file stepper_example.c
 */

#include <stdio.h>
#include <robotcontrol.h> // includes ALL Robot Control subsystems

void step(int direction);

/**
 * This template contains these critical components
 * - ensure no existing instances are running and make new PID file
 * - start the signal handler
 * - initialize subsystems you wish to use
 * - while loop that checks for EXITING condition
 * - cleanup subsystems at the end
 *
 * @return     0 during normal operation, -1 on error
 */
int main()
{
	int position = 0;
	int direction = 1;
	
	// make sure another instance isn't running
	// if return value is -3 then a background process is running with
	// higher privaledges and we couldn't kill it, in which case we should
	// not continue or there may be hardware conflicts. If it returned -4
	// then there was an invalid argument that needs to be fixed.
	if(rc_kill_existing_process(2.0)<-2) return -1;

	// start signal handler so we can exit cleanly
	if(rc_enable_signal_handler()==-1){
		fprintf(stderr,"ERROR: failed to start signal handler\n");
		return -1;
	}

	// make PID file to indicate your project is running
	// due to the check made on the call to rc_kill_existing_process() above
	// we can be fairly confident there is no PID file already and we can
	// make our own safely.
	rc_make_pid_file();

	// Keep looping until state changes to EXITING
	rc_set_state(RUNNING);
	rc_led_set(RC_LED_GREEN, 1);
	rc_led_set(RC_LED_RED, 0);
	while(rc_get_state()!=EXITING){
		// do stepping here
		if(position >= 800){
			direction = -1;
		} else if(position <= 0) {
			direction = 1;
		}
		step(direction);
		position += direction;

		// always sleep at some point
		rc_usleep(10000);
	}

	// turn off LEDs and close file descriptors
	rc_led_set(RC_LED_GREEN, 0);
	rc_led_set(RC_LED_RED, 0);
	rc_remove_pid_file();	// remove pid file LAST
	return 0;
}

#define M1 1
#define M2 4

void step(int direction)
{
	static int state = 0;
	static int enabled = 0;
	
	if(!enabled) {
		rc_motor_init();
		enabled = 1;
	}
	
	if(direction > 0) {
		state++;
	} else if (direction < 0) {
		state--;
	}
	
	if(state > 4) state = 0;
	else if(state < 0) state = 3;
	
	switch(state) {
		case 0:
		default:
			rc_motor_set(M1,1);
			rc_motor_set(M2,1);
			break;
		case 1:
			rc_motor_set(M1,-1);
			rc_motor_set(M2,1);
			break;
		case 2:
			rc_motor_set(M1,-1);
			rc_motor_set(M2,-1);
			break;
		case 3:
			rc_motor_set(M1,1);
			rc_motor_set(M2,-1);
			break;
	}
}