+# Much code from https://github.com/vsergeev/python-periphery/blob/master/periphery/pwm.py
+# Copyright (c) 2015-2016 vsergeev / Ivan (Vanya) A. Sergeev
+# License: MIT
+
+import os
+import digitalio
+
+try:
+ from microcontroller.pin import pwmOuts
+except ImportError:
+ raise RuntimeError("No PWM outputs defined for this board")
+
+class PWMError(IOError):
+ """Base class for PWM errors."""
+ pass
+
+
+class PWMOut(object):
+ # Sysfs paths
+ _sysfs_path = "/sys/class/pwm/"
+ _channel_path = "pwmchip{}"
+
+ # Channel paths
+ _export_path = "export"
+ _pin_path = "pwm{}"
+
+ # Pin attribute paths
+ _pin_period_path = "period"
+ _pin_duty_cycle_path = "duty_cycle"
+ _pin_polarity_path = "polarity"
+ _pin_enable_path = "enable"
+
+ def __init__(self, pin, *, frequency=500, duty_cycle=0, variable_frequency=False):
+ """Instantiate a PWM object and open the sysfs PWM corresponding to the
+ specified channel and pin.
+
+ Args:
+ pin (Pin): CircuitPython Pin object to output to
+ duty_cycle (int) : The fraction of each pulse which is high. 16-bit
+ frequency (int) : target frequency in Hertz (32-bit)
+ variable_frequency (bool) : True if the frequency will change over time
+
+ Returns:
+ PWMOut: PWMOut object.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if `channel` or `pin` types are invalid.
+ ValueError: if PWM channel does not exist.
+
+ """
+
+ self._pwmpin = None
+ self._open(pin, duty_cycle, frequency, variable_frequency)
+
+ def __del__(self):
+ self.close()
+
+ def __enter__(self):
+ return self
+
+ def __exit__(self, t, value, traceback):
+ self.close()
+
+ def _open(self, pin, duty=0, freq=500, variable_frequency=False):
+ self._channel = None
+ for pwmpair in pwmOuts:
+ if pwmpair[1] == pin:
+ self._channel = pwmpair[0][0]
+ self._pwmpin = pwmpair[0][1]
+
+ self._pin = pin
+ if self._channel is None:
+ raise RuntimeError("No PWM channel found for this Pin")
+
+ channel_path = os.path.join(self._sysfs_path, self._channel_path.format(self._channel))
+ if not os.path.isdir(channel_path):
+ raise ValueError("PWM channel does not exist, check that the required modules are loaded.")
+
+ pin_path = os.path.join(channel_path, self._pin_path.format(self._pwmpin))
+ if not os.path.isdir(pin_path):
+ try:
+ with open(os.path.join(channel_path, self._export_path), "w") as f_export:
+ f_export.write("%d\n" % self._pwmpin)
+ except IOError as e:
+ raise PWMError(e.errno, "Exporting PWM pin: " + e.strerror)
+
+ self._set_enabled(True)
+
+ # Look up the period, for fast duty cycle updates
+ self._period = self._get_period()
+
+ # set frequency
+ self.frequency = freq
+ # set duty
+ self.duty_cycle = duty
+
+ def close(self):
+ """Close the sysfs PWM."""
+ self._channel = None
+ self._pwmpin = None
+
+ def _write_pin_attr(self, attr, value):
+ path = os.path.join(
+ self._sysfs_path,
+ self._channel_path.format(self._channel),
+ self._pin_path.format(self._pwmpin),
+ attr)
+
+ with open(path, 'w') as f_attr:
+ #print(value, path)
+ f_attr.write(value + "\n")
+
+ def _read_pin_attr(self, attr):
+ path = os.path.join(
+ self._sysfs_path,
+ self._channel_path.format(self._channel),
+ self._pin_path.format(self._pwmpin),
+ attr)
+
+ with open(path, 'r') as f_attr:
+ return f_attr.read().strip()
+
+ # Mutable properties
+
+ def _get_period(self):
+ try:
+ period_ns = int(self._read_pin_attr(self._pin_period_path))
+ except ValueError:
+ raise PWMError(None, "Unknown period value: \"%s\"" % period_ns)
+
+ # Convert period from nanoseconds to seconds
+ period = period_ns / 1e9
+
+ # Update our cached period
+ self._period = period
+
+ return period
+
+ def _set_period(self, period):
+ if not isinstance(period, (int, float)):
+ raise TypeError("Invalid period type, should be int or float.")
+
+ # Convert period from seconds to integer nanoseconds
+ period_ns = int(period * 1e9)
+
+ self._write_pin_attr(self._pin_period_path, "{}".format(period_ns))
+
+ # Update our cached period
+ self._period = float(period)
+
+ """Get or set the PWM's output period in seconds.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not int or float.
+
+ :type: int, float
+ """
+
+ def _get_duty_cycle(self):
+ try:
+ duty_cycle_ns = int(self._read_pin_attr(self._pin_duty_cycle_path))
+ except ValueError:
+ raise PWMError(None, "Unknown duty cycle value: \"%s\"" % duty_cycle_ns)
+
+ # Convert duty cycle from nanoseconds to seconds
+ duty_cycle = duty_cycle_ns / 1e9
+
+ # Convert duty cycle to ratio from 0.0 to 1.0
+ duty_cycle = duty_cycle / self._period
+
+ # convert to 16-bit
+ duty_cycle = int(duty_cycle * 65535)
+
+ return duty_cycle
+
+ def _set_duty_cycle(self, duty_cycle):
+ # convert from 16-bit
+ duty_cycle /= 65535
+
+ if not isinstance(duty_cycle, (int, float)):
+ raise TypeError("Invalid duty cycle type, should be int or float.")
+ elif not 0.0 <= duty_cycle <= 1.0:
+ raise ValueError("Invalid duty cycle value, should be between 0.0 and 1.0.")
+
+ # Convert duty cycle from ratio to seconds
+ duty_cycle = duty_cycle * self._period
+
+ # Convert duty cycle from seconds to integer nanoseconds
+ duty_cycle_ns = int(duty_cycle * 1e9)
+
+ self._write_pin_attr(self._pin_duty_cycle_path, "{}".format(duty_cycle_ns))
+
+ duty_cycle = property(_get_duty_cycle, _set_duty_cycle)
+ """Get or set the PWM's output duty cycle as a ratio from 0.0 to 1.0.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not int or float.
+ ValueError: if value is out of bounds of 0.0 to 1.0.
+
+ :type: int, float
+ """
+
+ def _get_frequency(self):
+ return 1.0 / self._get_period()
+
+ def _set_frequency(self, frequency):
+ if not isinstance(frequency, (int, float)):
+ raise TypeError("Invalid frequency type, should be int or float.")
+
+ self._set_period(1.0 / frequency)
+
+ frequency = property(_get_frequency, _set_frequency)
+ """Get or set the PWM's output frequency in Hertz.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not int or float.
+
+ :type: int, float
+ """
+
+ def _get_enabled(self):
+ enabled = self._read_pin_attr(self._pin_enable_path)
+
+ if enabled == "1":
+ return True
+ elif enabled == "0":
+ return False
+
+ raise PWMError(None, "Unknown enabled value: \"%s\"" % enabled)
+
+ def _set_enabled(self, value):
+ if not isinstance(value, bool):
+ raise TypeError("Invalid enabled type, should be string.")
+
+ self._write_pin_attr(self._pin_enable_path, "1" if value else "0")
+
+ """Get or set the PWM's output enabled state.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not bool.
+
+ :type: bool
+ """
+
+ # String representation
+
+ def __str__(self):
+ return "PWM%d, pin %s (freq=%f Hz, duty_cycle=%f%%)" % \
+ (self._channel, self._pin, self.frequency, self.duty_cycle * 100,)
projects / Adafruit_Blinka-hackapet.git / commitdiff