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SDL_Pi_GROVE_Stepper.py
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#!/usr/bin/env python
# modified by SwitchDoc Labs for the Grove DRV8330 Stepper motor
# roughly based on Hercules_Stepper.cpp Seeed Technology
from time import sleep
class SDL_Pi_GROVE_Stepper():
def __init__(self, GroveDRV8830, number_of_steps ):
self._GroveDRV8830 = GroveDRV8830
self.SPD_BUFF_STEPS = 100
self.step_number = 0 # which step the motor is on
self.direction = 0 # motor direction
self.number_of_steps = number_of_steps; # total number of steps for this motor
# pin_count is used by the stepMotor() method:
self.pin_count = 4;
# Sets the speed in revs per minute
def setSpeed(self, rpm_start, rpm_max):
self.delay_max_speed = 60 * 1000 *1000 / self.number_of_steps / rpm_max;
self.delay_start_speed = 60 * 1000 * 1000/ self.number_of_steps / rpm_start;
return
# Moves the motor steps_to_move steps. If the number is negative,
# the motor moves in the reverse direction.
def step(self, steps_to_move):
steps_left = abs(steps_to_move) # how many steps to take
steps_orig = steps_left
steps_buffer = self.SPD_BUFF_STEPS
if (steps_orig < steps_buffer*2):
steps_buffer = steps_left/2;
delays = self.delay_start_speed;
delay_minus = (delays - self.delay_max_speed)/self.SPD_BUFF_STEPS;
# determine direction based on whether steps_to_mode is + or -:
if (steps_to_move > 0):
self.direction = 1
if (steps_to_move < 0):
self.direction = 0
# decrement the number of steps, moving one step each time:
while(steps_left > 0):
sleep(delays/1000000.0) # in microseconds
if (self.direction == 1):
self.step_number = self.step_number+1
if (self.step_number == self.number_of_steps):
self.step_number = 0;
else:
if (self.step_number == 0):
self.step_number = self.number_of_steps;
self.step_number= self.step_number -1
# decrement the steps left:
steps_left = steps_left-1;
if ((steps_orig - steps_left) <= steps_buffer):
delays = delays - delay_minus
else:
if (steps_left <= steps_buffer):
delays = delays+delay_minus
# step the motor to step number 0, 1, 2, or 3:
self.stepMotor(self.step_number % 4);
# Moves the motor forward or backwards.
def stepMotor(self, thisStep):
if (self.pin_count == 4):
if (thisStep == 0): # 1010
self._GroveDRV8830.drive(0, 100);
self._GroveDRV8830.drive(1, 100);
return
if (thisStep == 1): # 0110
self._GroveDRV8830.drive(0,-100);
self._GroveDRV8830.drive(1, 100);
return
if (thisStep == 2): # 0101
self._GroveDRV8830.drive(0,-100);
self._GroveDRV8830.drive(1,-100);
return
if (thisStep == 3): # 1001
self._GroveDRV8830.drive(0, 100);
self._GroveDRV8830.drive(1,-100);
return
self._GroveDRV8830.drive(0);
self._GroveDRV8830.drive(0);