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"""
# Xytronic LF-1600
# Open Source firmware
# PWM calculation
#
# Copyright (c) 2019 Michael Buesch <m@bues.ch>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
"""
__all__ = [
"PWMGenerator",
]
class PWMGenerator(object):
__slots__ = (
"f",
"duty",
"cycleT",
"out",
"__errors",
)
def __init__(self, f, duty=0.0):
self.f = max(f, 0.0)
self.duty = max(min(duty, 1.0), 0.0)
self.cycleT = 0.0
self.out = False
self.__errors = 0
@property
def cycleDur(self):
return 1.0 / self.f
def calc(self, dt):
if self.f:
self.cycleT += dt
dur = self.cycleDur
wrap = False
if self.out:
if self.cycleT >= dur:
if self.duty < 1.0:
self.out = False
wrap = True
else:
if self.cycleT >= dur * (1.0 - self.duty):
if self.duty > 0.0:
self.out = True
else:
wrap = True
if wrap:
self.cycleT -= dur
if self.cycleT >= dur:
if self.__errors < 10:
print("The PWM frequency %f Hz is "
"too fast. Loosing steps." % (
self.f))
self.__errors += 1
self.cycleT = 0.0
return self.out
if __name__ == "__main__":
import time
pwm = PWMGenerator(f=0.5, duty=0.3)
dt = 0.1
i = 0.0
while 1:
out = pwm.calc(dt)
print("t=%.1f, out=%d, cycleT=%.3f" % (i, int(out), pwm.cycleT))
time.sleep(dt)
i += dt
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