159 lines
4.3 KiB
Python
159 lines
4.3 KiB
Python
# SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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"""Custom PWMOut Wrapper for Jetson GPIO PWM Class"""
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from RPi import GPIO
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GPIO.setmode(GPIO.TEGRA_SOC) # Use BCM pins D4 = GPIO #4
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GPIO.setwarnings(True) # shh!
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class PWMError(IOError):
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"""Base class for PWM errors."""
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class PWMOut:
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"""Pulse Width Modulation Output Class"""
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def __init__(self, pin, *, frequency=500, duty_cycle=0, variable_frequency=False):
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self._pwmpin = None
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self._period = 0
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self._open(pin, duty_cycle, frequency, variable_frequency)
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def __del__(self):
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self.deinit()
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def __enter__(self):
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return self
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def __exit__(self, t, value, traceback):
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self.deinit()
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def _open(self, pin, duty=0, freq=500, variable_frequency=False):
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self._pin = pin
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GPIO.setup(pin.id, GPIO.OUT, initial=GPIO.HIGH)
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self._pwmpin = GPIO.PWM(pin.id, freq)
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if variable_frequency:
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print("Variable Frequency is not supported, continuing without it...")
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# set frequency
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self.frequency = freq
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# set duty
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self.duty_cycle = duty
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self.enabled = True
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def deinit(self):
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"""Deinit the PWM."""
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if self._pwmpin is not None:
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self._pwmpin.stop()
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GPIO.cleanup(self._pin.id)
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self._pwmpin = None
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def _is_deinited(self):
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if self._pwmpin is None:
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raise ValueError(
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"Object has been deinitialize and can no longer "
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"be used. Create a new object."
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)
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@property
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def period(self):
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"""Get or set the PWM's output period in seconds.
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Raises:
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PWMError: if an I/O or OS error occurs.
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TypeError: if value type is not int or float.
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:type: int, float
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"""
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return 1.0 / self.frequency
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@period.setter
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def period(self, period):
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if not isinstance(period, (int, float)):
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raise TypeError("Invalid period type, should be int or float.")
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self.frequency = 1.0 / period
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@property
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def duty_cycle(self):
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"""Get or set the PWM's output duty cycle which is the fraction of
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each pulse which is high. 16-bit
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Raises:
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PWMError: if an I/O or OS error occurs.
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TypeError: if value type is not int or float.
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ValueError: if value is out of bounds of 0.0 to 1.0.
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:type: int, float
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"""
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return int(self._duty_cycle * 65535)
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@duty_cycle.setter
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def duty_cycle(self, duty_cycle):
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if not isinstance(duty_cycle, (int, float)):
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raise TypeError("Invalid duty cycle type, should be int or float.")
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if not 0 <= duty_cycle <= 65535:
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raise ValueError("Invalid duty cycle value, should be between 0 and 65535")
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# convert from 16-bit
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duty_cycle /= 65535.0
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self._duty_cycle = duty_cycle
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self._pwmpin.ChangeDutyCycle(round(self._duty_cycle * 100))
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@property
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def frequency(self):
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"""Get or set the PWM's output frequency in Hertz.
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Raises:
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PWMError: if an I/O or OS error occurs.
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TypeError: if value type is not int or float.
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:type: int, float
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"""
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return self._frequency
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@frequency.setter
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def frequency(self, frequency):
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if not isinstance(frequency, (int, float)):
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raise TypeError("Invalid frequency type, should be int or float.")
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self._pwmpin.ChangeFrequency(round(frequency))
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self._frequency = frequency
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@property
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def enabled(self):
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"""Get or set the PWM's output enabled state.
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Raises:
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PWMError: if an I/O or OS error occurs.
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TypeError: if value type is not bool.
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:type: bool
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"""
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return self._enabled
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@enabled.setter
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def enabled(self, value):
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if not isinstance(value, bool):
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raise TypeError("Invalid enabled type, should be string.")
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if value:
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self._pwmpin.start(round(self._duty_cycle * 100))
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else:
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self._pwmpin.stop()
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self._enabled = value
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# String representation
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def __str__(self):
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return "pin %s (freq=%f Hz, duty_cycle=%f%%)" % (
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self._pin,
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self.frequency,
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self.duty_cycle,
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)
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