This implements a Stepper class currently missing in gpiozero's API [4].
This code is somewhat an adaptation of Arduino's built-in Stepper class [1,2].
Tested and works on unipolar stepper motor 28BYJ-48 with UL2003AN driver. However, during tests, higher rpm settings (>1600) caused motor to intermittently stop. Motor seem to work fine however with about 1500 rpm, or about 1.25ms delay.
Example 1: Setting rotation speed and doing full or half turn
import sys
from time import sleep
from gpiostepper import Stepper
if __name__ == "__main__":
if len(sys.argv) > 1:
speed = int(sys.argv[1])
else:
speed = 100
print("Speed: {} rpm".format(speed))
number_of_steps = 32
step_motor1 = Stepper(motor_pins=[17, 18, 22, 23], number_of_steps = number_of_steps)
step_motor1.set_speed(speed)
amount_of_gear_reduction = 64
number_of_steps_per_revolution_geared_output = number_of_steps * amount_of_gear_reduction
# Do a full CW rotation
print("One Full Clockwise Rotation")
step_motor1.step(number_of_steps_per_revolution_geared_output)
sleep(1)
# Do a half CCW rotation
print("Half Counter-clockwise Rotation Slowly")
step_motor1.set_speed(speed/3)
step_motor1.step(-number_of_steps_per_revolution_geared_output/2)Example 2: Setting step sequence and rotating indefinitely
import sys
from time import sleep
from gpiostepper import Stepper
if __name__ == "__main__":
if len(sys.argv) > 1:
speed = int(sys.argv[1])
else:
speed = 100
print("Speed: {} rpm".format(speed))
number_of_steps = 32
step_motor2 = Stepper(
motor_pins=[17, 22, 18, 23],
number_of_steps = number_of_steps,
step_sequence = [[1,0,1,0], [0,1,1,0], [0,1,0,1], [1,0,0,1]]
)
step_motor2.set_speed(speed)
# Rotate CW indefinitely
print("Clockwise Rotation")
step_motor2.forward()Important! With the step sequence similar to [2], you need to specify the output pins in 1-3-2-4 sequence. This video [3] explains why it's so: https://youtu.be/0qwrnUeSpYQ?t=1068
- Stepper Library. https://www.arduino.cc/en/Reference/Stepper
- Stepper.cpp. https://github.com/arduino-libraries/Stepper/blob/master/src/Stepper.cpp
- Stepper Motors with Arduino - Controlling Bipolar & Unipolar stepper motors. https://www.youtube.com/watch?v=0qwrnUeSpYQ
- Add Stepper Motor. gpiozero/gpiozero#144