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scanengine-3/core/rotation.py
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Thomas K Ales [MSE] 880b05fe86 working state commit
2026-09-25 08:13:03 -05:00

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Python
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"""GR rotation axis: the T3R configuration and move policy for scanning.
Qt-free façade over hardware.t3r_driver.T3RDriver that owns the drive
settings the scan depends on, so the engine never re-derives them.
"""
from __future__ import annotations
import logging
from dataclasses import dataclass
logger = logging.getLogger(__name__)
@dataclass(frozen=True)
class RotationSettings:
"""Drive settings for the GR axis during a scan."""
microsteps: int = 8 # microsteps/full-step on the GR axis (ch3)
velocity: int = 4000 # steps/s for inter-angle moves
accel: int = 2000 # steps/s² for inter-angle moves
run_current_ma: int = 1200 # drive current while moving
hold_current_ma: int = 400 # standstill current
ihold_delay: int = 6 # run→hold current ramp delay (TMC IHOLDDELAY units)
# The sample rotates CW instead of CCW to clear wiring and avoid a stall.
rotation_sign: int = -1
DEFAULT_ROTATION = RotationSettings()
class RotationAxis:
"""Blocking rotation control for the GR axis.
``configure()`` must run before any move: ``steps_for_angle()`` assumes
the configured microstep setting, so the device has to be told to match
rather than trusting whatever the T3R panel or firmware default left it
at.
"""
def __init__(self, driver, settings: RotationSettings = DEFAULT_ROTATION):
self.driver = driver
self.settings = settings
self._current_deg = 0.0
@property
def is_available(self) -> bool:
return self.driver is not None and self.driver.is_open
@property
def current_deg(self) -> float:
return self._current_deg
def configure(self) -> None:
s = self.settings
ch = self.driver.GR_AXIS_CH
self.driver.set_microstep(ch, s.microsteps)
self.driver.set_current(ch, s.run_current_ma, s.hold_current_ma, s.ihold_delay)
self.driver.enable(ch)
def estimate_move_secs(self, delta_deg: float) -> float:
"""Trapezoidal move time: cruise + accel/decel ramps."""
s = self.settings
steps = abs(self.driver.steps_for_angle(delta_deg, s.microsteps))
return steps / s.velocity + s.velocity / s.accel
def rotate_to(self, angle_deg: float, timeout_margin_s: float = 5.0) -> float:
"""Rotate to an absolute angle and block until the move completes.
Returns the estimated move time (for status reporting). Waits on the
driver's MOTION_DONE event rather than sleeping for a guessed
duration; falls back to the estimate only if the event never arrives.
"""
delta_deg = angle_deg - self._current_deg
if abs(delta_deg) <= 0.001:
return 0.0
s = self.settings
est_secs = self.estimate_move_secs(delta_deg)
self.driver.rotate_stage(delta_deg, s.microsteps, s.velocity, s.accel)
if not self.driver.wait_motion_done(self.driver.GR_AXIS_CH,
est_secs + timeout_margin_s):
logger.warning(
"GR axis did not report MOTION_DONE within %.1f s for a "
"%.1f° move; continuing", est_secs + timeout_margin_s, delta_deg)
self._current_deg = angle_deg
return est_secs
def return_to_zero(self) -> float:
return self.rotate_to(0.0)