imptube.pistepper

  1""" An example implementation of the Stepper class for movable termination.
  2In this case, implemented for the original impedance tube operated solely
  3by Raspberry Pi 4 Model B. Because of some sound stability issues,
  4newer implementation relies on FT232H breakout board from Adafruit.
  5
  6This module provides a PiStepper class that contains methods for controlling
  7a stepper motor using a Raspberry Pi and a DRV8825 driver. The class allows
  8for setting the microstepping resolution, defining the ramping of the motor
  9speed, initiating GPIO settings, enabling/disabling the motor, and performing
 10the actual spinning of the motor.
 11
 12Constants:
 13- DIR: Direction GPIO Pin
 14- STEP: Step GPIO Pin
 15- MODE: Microstep Resolution GPIO Pins
 16- ENABLE: Enable GPIO Pin
 17- CW: Clockwise Rotation
 18- CCW: Counterclockwise Rotation
 19- SPR: Steps per Revolution
 20- FREQ: Frequency
 21- RESOLUTION: Dictionary mapping microstepping resolution names to GPIO pin values
 22- RESOLUTION_M: Dictionary mapping microstepping resolution names to step multipliers
 23
 24"""
 25from time import sleep
 26# import RPi.GPIO as GPIO
 27import numpy as np
 28
 29DIR = 20   # Direction GPIO Pin
 30STEP = 21 # Step GPIO Pin
 31MODE = (14, 15, 18)   # Microstep Resolution GPIO Pins
 32ENABLE = 16
 33
 34CW = 1     # Clockwise Rotation
 35CCW = 0    # Counterclockwise Rotation
 36SPR = 200   # Steps per Revolution
 37FREQ = 2
 38RESOLUTION = {'Full': (0, 0, 0),
 39              'Half': (1, 0, 0),
 40              '1/4': (0, 1, 0),
 41              '1/8': (1, 1, 0),
 42              '1/16': (0, 0, 1),
 43              '1/32': (1, 0, 1)}
 44RESOLUTION_M = {'Full': 1,
 45                'Half': 2,
 46                '1/4': 4,
 47                '1/8': 8,
 48                '1/16': 16,
 49                '1/32': 32}
 50
 51class PiStepper:
 52    """
 53    Contains methods for stepper motor operation using Pi and DRV8825 driver
 54    
 55    Attributes:
 56    ----------
 57    res : str
 58        The microstepping resolution of the stepper motor.
 59    delay : numpy.ndarray
 60        The delay values for each step in the stepper motor movement.
 61    
 62    Methods:
 63    --------
 64    __init__(res="Half"):
 65        Initializes a PiStepper object with the specified microstepping resolution.
 66        
 67        Parameters:
 68        ----------
 69        res : str, optional
 70            The microstepping resolution of the stepper motor. Default is "Half".
 71    
 72    set_delay(step_count, fade=1, sin_begin=4):
 73        Sets the delay values for each step in the stepper motor movement.
 74        
 75        Parameters:
 76        ----------
 77        step_count : int
 78            The total number of steps in the stepper motor movement.
 79        fade : float, optional
 80            The duration of the ramping effect at the beginning and end of the movement. Default is 1.
 81        sin_begin : int, optional
 82            The number of steps over which the ramping effect is applied. Default is 4.
 83    
 84    on():
 85        Initializes the GPIO settings for the stepper motor operation.
 86    
 87    off():
 88        Cleans up the GPIO settings after the stepper motor operation.
 89    
 90    enable():
 91        Enables the stepper motor by operating the ENABLE pin on the driver.
 92    
 93    disable():
 94        Disables the stepper motor by operating the ENABLE pin on the driver.
 95    
 96    turn(revolutions=1, clockwise=True):
 97        Performs the actual spinning of the stepper motor.
 98        
 99        Parameters:
100        ----------
101        revolutions : float, optional
102            The number of full revolutions to be performed by the stepper motor. Default is 1.
103        clockwise : bool, optional
104            Specifies the direction of rotation. True for clockwise, False for counterclockwise. Default is True.
105    """
106
107    def __init__(self, res="Half"):
108        """
109        Initializes a PiStepper object with the specified microstepping resolution.
110        
111        Parameters:
112        ----------
113        res : str, optional
114            The microstepping resolution of the stepper motor. Default is "Half".
115        """
116        self.res = res
117
118    def set_delay(self, step_count, fade=1, sin_begin=4):
119        """
120        Sets the delay values for each step in the stepper motor movement.
121        
122        Parameters:
123        ----------
124        step_count : int
125            The total number of steps in the stepper motor movement.
126        fade : float, optional
127            The duration of the ramping effect at the beginning and end of the movement. Default is 1.
128        sin_begin : int, optional
129            The number of steps over which the ramping effect is applied. Default is 4.
130        """
131        self.delay = np.full(
132            step_count,
133            1 / FREQ / SPR / RESOLUTION_M[self.res]
134            )
135        len_fade = int(fade * SPR)
136        ramp_in = 1/np.sin(np.linspace(
137            np.pi/sin_begin,
138            np.pi/2,
139            len_fade
140            ))
141        ramp_out = 1/np.sin(np.linspace(
142            np.pi/2,
143            np.pi - np.pi/sin_begin,
144            len_fade
145            ))
146        ramp_shape = ramp_in.shape[0]
147        self.delay[0:ramp_shape] = self.delay[0:ramp_shape] * ramp_in
148        self.delay[-ramp_shape:] = self.delay[-ramp_shape:] * ramp_out
149
150    def on(self):
151        """
152        Initializes the GPIO settings for the stepper motor operation.
153        """
154        GPIO.setmode(GPIO.BCM)
155        GPIO.setup(DIR, GPIO.OUT)
156        GPIO.setup(STEP, GPIO.OUT)
157        GPIO.setup(ENABLE, GPIO.OUT)
158        GPIO.output(DIR, CW)
159        GPIO.setup(MODE, GPIO.OUT)
160
161        GPIO.output(MODE, RESOLUTION[self.res])
162
163    def off(self):
164        """
165        Cleans up the GPIO settings after the stepper motor operation.
166        """
167        GPIO.cleanup()
168
169    def enable(self):
170        """
171        Enables the stepper motor by operating the ENABLE pin on the driver.
172        """
173        GPIO.output(ENABLE, 0)
174
175    def disable(self):
176        """
177        Disables the stepper motor by operating the ENABLE pin on the driver.
178        """
179        GPIO.output(ENABLE, 1)
180
181
182    def turn(self, revolutions=1, clockwise=True):
183        """
184        Performs the actual spinning of the stepper motor.
185        
186        Parameters:
187        ----------
188        revolutions : float, optional
189            The number of full revolutions to be performed by the stepper motor. Default is 1.
190        clockwise : bool, optional
191            Specifies the direction of rotation. True for clockwise, False for counterclockwise. Default is True.
192        """
193        if clockwise:
194            GPIO.output(DIR, CW)
195        else:
196            GPIO.output(DIR, CCW)
197
198        step_count = int(revolutions * SPR * RESOLUTION_M[self.res])
199        
200        self.set_delay(step_count)
201
202        for d in self.delay:
203            GPIO.output(STEP, GPIO.HIGH)
204            sleep(d)
205            GPIO.output(STEP, GPIO.LOW)
206            sleep(d)
207
208
209
210if __name__ == "__main__":
211    p = PiStepper()
212    p.on()
213    p.turn(0.75)
214    p.off()
215
216
217