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# Printer stepper support
#
# Copyright (C) 2016,2017 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import math, logging
import homing, pins
# Code storing the definitions for a stepper motor
class PrinterStepper:
def __init__(self, printer, config):
self.name = config.section
if self.name.startswith('stepper_'):
self.name = self.name[8:]
self.step_dist = config.getfloat('step_distance', above=0.)
self.inv_step_dist = 1. / self.step_dist
self.min_stop_interval = 0.
self.mcu_stepper = pins.setup_pin(
printer, 'stepper', config.get('step_pin'))
dir_pin_params = pins.get_printer_pins(printer).parse_pin_desc(
config.get('dir_pin'), can_invert=True)
self.mcu_stepper.setup_dir_pin(dir_pin_params)
self.mcu_stepper.setup_step_distance(self.step_dist)
enable_pin = config.get('enable_pin', None)
self.mcu_enable = None
if enable_pin is not None:
self.mcu_enable = pins.setup_pin(printer, 'digital_out', enable_pin)
self.mcu_enable.setup_max_duration(0.)
self.need_motor_enable = True
def _dist_to_time(self, dist, start_velocity, accel):
# Calculate the time it takes to travel a distance with constant accel
time_offset = start_velocity / accel
return math.sqrt(2. * dist / accel + time_offset**2) - time_offset
def set_max_jerk(self, max_halt_velocity, max_accel):
# Calculate the firmware's maximum halt interval time
last_step_time = self._dist_to_time(
self.step_dist, max_halt_velocity, max_accel)
second_last_step_time = self._dist_to_time(
2. * self.step_dist, max_halt_velocity, max_accel)
min_stop_interval = second_last_step_time - last_step_time
self.mcu_stepper.setup_min_stop_interval(min_stop_interval)
def motor_enable(self, print_time, enable=0):
if enable and self.need_motor_enable:
self.mcu_stepper.reset_step_clock(print_time)
if (self.mcu_enable is not None
and self.mcu_enable.get_last_setting() != enable):
self.mcu_enable.set_digital(print_time, enable)
self.need_motor_enable = not enable
# Support for stepper controlled linear axis with an endstop
class PrinterHomingStepper(PrinterStepper):
def __init__(self, printer, config):
PrinterStepper.__init__(self, printer, config)
# Endstop and its position
self.mcu_endstop = pins.setup_pin(
printer, 'endstop', config.get('endstop_pin'))
self.mcu_endstop.add_stepper(self.mcu_stepper)
self.position_endstop = config.getfloat('position_endstop')
# Axis range
self.position_min = config.getfloat('position_min', 0.)
self.position_max = config.getfloat(
'position_max', 0., above=self.position_min)
# Homing mechanics
self.homing_speed = config.getfloat('homing_speed', 5.0, above=0.)
self.homing_retract_dist = config.getfloat(
'homing_retract_dist', 5., above=0.)
self.homing_positive_dir = config.getboolean('homing_positive_dir', None)
if self.homing_positive_dir is None:
axis_len = self.position_max - self.position_min
if self.position_endstop <= self.position_min + axis_len / 4.:
self.homing_positive_dir = False
elif self.position_endstop >= self.position_max - axis_len / 4.:
self.homing_positive_dir = True
else:
raise config.error(
"Unable to infer homing_positive_dir in section '%s'" % (
config.section,))
# Endstop stepper phase position tracking
self.homing_stepper_phases = config.getint(
'homing_stepper_phases', None, minval=0)
endstop_accuracy = config.getfloat(
'homing_endstop_accuracy', None, above=0.)
self.homing_endstop_accuracy = self.homing_endstop_phase = None
if self.homing_stepper_phases:
self.homing_endstop_phase = config.getint(
'homing_endstop_phase', None, minval=0
, maxval=self.homing_stepper_phases-1)
if self.homing_endstop_phase is not None:
# Adjust the endstop position so 0.0 is always at a full step
micro_steps = self.homing_stepper_phases // 4
phase_offset = (
((self.homing_endstop_phase + micro_steps // 2) % micro_steps)
- micro_steps // 2) * self.step_dist
full_step = micro_steps * self.step_dist
es_pos = (int(self.position_endstop / full_step + .5) * full_step
+ phase_offset)
if es_pos != self.position_endstop:
logging.info("Changing %s endstop position to %.3f"
" (from %.3f)", self.name, es_pos,
self.position_endstop)
self.position_endstop = es_pos
if endstop_accuracy is None:
self.homing_endstop_accuracy = self.homing_stepper_phases//2 - 1
elif self.homing_endstop_phase is not None:
self.homing_endstop_accuracy = int(math.ceil(
endstop_accuracy * self.inv_step_dist / 2.))
else:
self.homing_endstop_accuracy = int(math.ceil(
endstop_accuracy * self.inv_step_dist))
if self.homing_endstop_accuracy >= self.homing_stepper_phases // 2:
logging.info("Endstop for %s is not accurate enough for stepper"
" phase adjustment", name)
self.homing_stepper_phases = None
if self.mcu_endstop.get_mcu().is_fileoutput():
self.homing_endstop_accuracy = self.homing_stepper_phases
def get_homing_speed(self):
# Round the configured homing speed so that it is an even
# number of ticks per step.
adjusted_freq = self.mcu_stepper.get_mcu().get_adjusted_freq()
dist_ticks = adjusted_freq * self.step_dist
ticks_per_step = round(dist_ticks / self.homing_speed)
return dist_ticks / ticks_per_step
def get_homed_offset(self):
if not self.homing_stepper_phases or self.need_motor_enable:
return 0
pos = self.mcu_stepper.get_mcu_position()
pos %= self.homing_stepper_phases
if self.homing_endstop_phase is None:
logging.info("Setting %s endstop phase to %d", self.name, pos)
self.homing_endstop_phase = pos
return 0
delta = (pos - self.homing_endstop_phase) % self.homing_stepper_phases
if delta >= self.homing_stepper_phases - self.homing_endstop_accuracy:
delta -= self.homing_stepper_phases
elif delta > self.homing_endstop_accuracy:
raise homing.EndstopError(
"Endstop %s incorrect phase (got %d vs %d)" % (
self.name, pos, self.homing_endstop_phase))
return delta * self.step_dist
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