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stepcompress: Pass constant velocity and acceleration directly to C code

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Update the C code to take velocity and acceleration directly in step
distances and clock ticks.  This simplifies the mcu.py python code as
it only needs to do unit and axis conversion.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2017-04-04 19:54:32 -04:00
parent e4153a536f
commit 1d81bf5596
3 changed files with 32 additions and 38 deletions
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26
klippy/mcu.py
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@ -29,7 +29,7 @@ class MCU_stepper:
self._dir_pin, pullup, self._invert_dir = parse_pin_extras(dir_pin)
self._commanded_pos = 0
self._step_dist = self._inv_step_dist = 1.
self._velocity_factor = self._inv_accel_factor = 0.
self._velocity_factor = self._accel_factor = 0.
self._mcu_position_offset = 0
self._mcu_freq = self._min_stop_interval = 0.
self._reset_cmd = self._get_position_cmd = None
@ -43,7 +43,7 @@ class MCU_stepper:
def build_config(self):
self._mcu_freq = self._mcu.get_mcu_freq()
self._velocity_factor = 1. / (self._mcu_freq * self._step_dist)
self._inv_accel_factor = self._mcu_freq**2 * self._step_dist
self._accel_factor = 1. / (self._mcu_freq**2 * self._step_dist)
max_error = self._mcu.get_max_stepper_error()
min_stop_interval = max(0., self._min_stop_interval - max_error)
self._mcu.add_config_cmd(
@ -119,29 +119,21 @@ class MCU_stepper:
else:
self._commanded_pos -= 1
def step_const(self, mcu_time, start_pos, dist, cruise_v):
#t = pos/cruise_v
inv_step_dist = self._inv_step_dist
step_offset = self._commanded_pos - start_pos * inv_step_dist
steps = dist * inv_step_dist
count = self._ffi_lib.stepcompress_push_factor(
self._stepqueue, steps, step_offset,
mcu_time * self._mcu_freq, 1. / (cruise_v * self._velocity_factor))
count = self._ffi_lib.stepcompress_push_const(
self._stepqueue, mcu_time * self._mcu_freq, step_offset,
dist * inv_step_dist, cruise_v * self._velocity_factor)
if count == STEPCOMPRESS_ERROR_RET:
raise error("Internal error in stepcompress")
self._commanded_pos += count
def step_accel(self, mcu_time, start_pos, dist, start_v, accel):
#t = sqrt(2*pos/accel + (start_v/accel)**2) - start_v/accel
inv_step_dist = self._inv_step_dist
mcu_freq = self._mcu_freq
inv_accel = 1. / accel
time_offset = start_v * inv_accel * mcu_freq
sqrt_offset = time_offset**2
step_offset = self._commanded_pos - start_pos * inv_step_dist
steps = dist * inv_step_dist
clock = mcu_time * mcu_freq - time_offset
count = self._ffi_lib.stepcompress_push_sqrt(
self._stepqueue, steps, step_offset, clock,
sqrt_offset, 2. * inv_accel * self._inv_accel_factor)
count = self._ffi_lib.stepcompress_push_accel(
self._stepqueue, mcu_time * self._mcu_freq, step_offset,
dist * inv_step_dist, start_v * self._velocity_factor,
accel * self._accel_factor)
if count == STEPCOMPRESS_ERROR_RET:
raise error("Internal error in stepcompress")
self._commanded_pos += count