--- /dev/null
+import os
+from time import sleep
+from errno import EACCES
+
+try:
+ from microcontroller.pin import pwmOuts
+except ImportError:
+ raise RuntimeError("No PWM outputs defined for this board.") from ImportError
+
+
+class PWMError(IOError):
+ """Base class for PWM errors."""
+
+ pass
+
+
+class PWMOut:
+ """Pulse Width Modulation Output Class"""
+
+ # Number of retries to check for successful PWM export on open
+ PWM_STAT_RETRIES = 10
+ # Delay between check for successful PWM export on open (100ms)
+ PWM_STAT_DELAY = 0.1
+
+ # Sysfs paths
+ _sysfs_path = "/sys/class/pwm"
+ _chip_path = "pwmchip{}"
+ _channel_path = "pwm{}"
+
+ # Sysfs commands
+ _export = "export"
+ _unexport = "unexport"
+
+ # Pin commands
+ _pin_period = "period"
+ _pin_duty_cycle = "duty_cycle"
+ _pin_polarity = "polarity"
+ _pin_enable = "enable"
+
+ def __init__(self, pwm, *, frequency=500, duty_cycle=0, variable_frequency=False):
+ """Instantiate a PWM object and open the sysfs PWM corresponding to the
+ specified chip and channel.
+ Args:
+ pwm (str): PWM pin.
+ frequency (int, float): target frequency in Hertz (32-bit).
+ duty_cycle (int, float): The fraction of each pulse which is high (16-bit).
+ variable_frequency (bool): True if the frequency will change over time.
+ Returns:
+ PWM: PWM object.
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if `chip` or `channel` types are invalid.
+ LookupError: if PWM chip does not exist.
+ TimeoutError: if waiting for PWM export times out.
+ """
+
+ self._chip = None
+ self._channel = None
+ self._period_ns = 0
+ self._open(pwm, frequency, duty_cycle, variable_frequency)
+
+ def __del__(self):
+ self.close()
+
+ def __enter__(self):
+ return self
+
+ def __exit__(self, exc_type, exc_val, exc_tb):
+ self.close()
+
+ def _open(self, pwm, frequency, duty_cycle, variable_frequency):
+ for pwmout in pwmOuts:
+ if pwmout[1] == pwm:
+ self._chip = pwmout[0][0]
+ self._channel = pwmout[0][1]
+
+ self._pwm = pwm
+
+ self._chip_path = os.path.join(self._sysfs_path, self._chip_path.format(self._chip))
+ self._channel_path = os.path.join(self._chip_path, self._channel_path.format(self._channel))
+
+ if not os.path.isdir(self._chip_path):
+ raise LookupError("Opening PWM: PWM chip {} not found.".format(self._chip))
+
+ if not os.path.isdir(self._channel_path):
+ # Exporting the PWM.
+ try:
+ with open(os.path.join(self._chip_path, self._export), "w") as f_export:
+ f_export.write("{:d}\n".format(self._channel))
+ except IOError as e:
+ raise PWMError(e.errno, "Exporting PWM channel: " + e.strerror)
+
+ # Loop until PWM is exported
+ exported = False
+ for i in range(PWMOut.PWM_STAT_RETRIES):
+ if os.path.isdir(self._channel_path):
+ exported = True
+ break
+
+ sleep(PWMOut.PWM_STAT_DELAY)
+
+ if not exported:
+ raise TimeoutError("Exporting PWM: waiting for \"{:s}\" timed out.".format(self._channel_path))
+
+ # Loop until 'period' is writable, This could take some time after
+ # export as application of the udev rules after export is asynchronous.
+ # Without this loop, the following properties may not be writable yet.
+ for i in range(PWMOut.PWM_STAT_RETRIES):
+ try:
+ with open(os.path.join(self._channel_path, "period"), "w",):
+ break
+ except IOError as e:
+ if e.errno != EACCES or (e.errno == EACCES and i == PWMOut.PWM_STAT_RETRIES - 1):
+ raise PWMError(e.errno, "Opening PWM period: " + e.strerror) from IOError
+
+ sleep(PWMOut.PWM_STAT_DELAY)
+
+ self.frequency = frequency
+ self.duty_cycle = duty_cycle
+
+ # Cache the period for fast duty cycle updates
+ self._period_ns = self._get_period_ns()
+
+ def close(self):
+ """Close the PWM."""
+ if self._channel is not None:
+ # Unexporting the PWM channel
+ try:
+ unexport_fd = os.open(os.path.join(self._chip_path, self._unexport), os.O_WRONLY)
+ os.write(unexport_fd, "{:d}\n".format(self._channel).encode())
+ os.close(unexport_fd)
+ except OSError as e:
+ raise PWMError(e.errno, "Unexporting PWM: " + e.strerror)
+
+ self._chip = None
+ self._channel = None
+
+ def _write_channel_attr(self, attr, value):
+ with open(os.path.join(self._channel_path, attr), 'w') as f_attr:
+ f_attr.write(value + "\n")
+
+ def _read_channel_attr(self, attr):
+ with open(os.path.join(self._channel_path, attr), 'r') as f_attr:
+ return f_attr.read().strip()
+
+ # Methods
+
+ def enable(self):
+ """Enable the PWM outout."""
+ self.enabled = True
+
+ def disable(self):
+ """Diable the PWM output."""
+ self.enabled = False
+
+ # Mutable properties
+
+ def _get_period(self):
+ return float(self.period_ms) / 1000
+
+ def _set_period(self, period):
+ if not isinstance(period, (int, float)):
+ raise TypeError("Invalid period type, should be int.")
+
+ self.period_ms = int(period * 1000)
+
+ period = property(_get_period, _set_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.
+
+ :type: int, float
+ """
+
+ def _get_period_ms(self):
+ return self.period_us / 1000
+
+ def _set_period_ms(self, period_ms):
+ if not isinstance(period_ms, int):
+ raise TypeError("Invalid period type, should be int.")
+ self.period_us = int(period_ms * 1000)
+
+ period_ms = property(_get_period_ms, _set_period_ms)
+ """Get or set the PWM's output period in milliseconds.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not int.
+
+ :type: int
+ """
+
+ def _get_period_us(self):
+ return self.period_ns / 1000
+
+ def _set_period_us(self, period_us):
+ if not isinstance(period_us, int):
+ raise TypeError("Invalid period type, should be int.")
+
+ self.period_ns = int(period_us * 1000)
+
+ period_us = property(_get_period_us, _set_period_us)
+ """Get or set the PWM's output period in microseconds.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not int.
+
+ :type: int
+ """
+
+ def _get_period_ns(self):
+ period_ns = self._read_channel_attr(self._pin_period)
+ try:
+ period_ns = int(period_ns)
+ except ValueError:
+ raise PWMError(None, "Unknown period value: \"%s\"." % period_ns) from ValueError
+
+ self._period_ns = period_ns
+
+ return period_ns
+
+ def _set_period_ns(self, period_ns):
+ if not isinstance(period_ns, int):
+ raise TypeError("Invalid period type, should be int.")
+
+ self._write_channel_attr("period", str(period_ns))
+
+ # Update our cached period
+ self._period_ns = period_ns
+
+ period_ns = property(_get_period_ns, _set_period_ns)
+ """Get or set the PWM's output period in nanoseconds.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not int.
+
+ :type: int
+ """
+
+ def _get_duty_cycle_ns(self):
+ duty_cycle_ns_str = self._read_channel_attr("duty_cycle")
+
+ try:
+ duty_cycle_ns = int(duty_cycle_ns_str)
+ except ValueError:
+ raise PWMError(None, "Unknown duty cycle value: \"{:s}\"".format(duty_cycle_ns_str))
+
+ return duty_cycle_ns
+
+ def _set_duty_cycle_ns(self, duty_cycle_ns):
+ if not isinstance(duty_cycle_ns, int):
+ raise TypeError("Invalid duty cycle type, should be int.")
+
+ self._write_channel_attr("duty_cycle", str(duty_cycle_ns))
+
+ duty_cycle_ns = property(_get_duty_cycle_ns, _set_duty_cycle_ns)
+ """Get or set the PWM's output duty cycle in nanoseconds.
+
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not int.
+
+ :type: int
+ """
+
+ def _get_duty_cycle(self):
+ return float(self.duty_cycle_ns) / self._period_ns
+
+ def _set_duty_cycle(self, duty_cycle):
+ 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 nanoseconds
+ self.duty_cycle_ns = int(duty_cycle * self._period_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.period
+
+ def _set_frequency(self, frequency):
+ if not isinstance(frequency, (int, float)):
+ raise TypeError("Invalid frequency type, should be int or float.")
+
+ self.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_polarity(self):
+ return self._read_channel_attr("polarity")
+
+ def _set_polarity(self, polarity):
+ if not isinstance(polarity, str):
+ raise TypeError("Invalid polarity type, should be str.")
+ elif polarity.lower() not in ["normal", "inversed"]:
+ raise ValueError("Invalid polarity, can be: \"normal\" or \"inversed\".")
+
+ self._write_channel_attr("polarity", polarity.lower())
+
+ polarity = property(_get_polarity, _set_polarity)
+ """Get or set the PWM's output polarity. Can be "normal" or "inversed".
+ Raises:
+ PWMError: if an I/O or OS error occurs.
+ TypeError: if value type is not str.
+ ValueError: if value is invalid.
+ :type: str
+ """
+
+ def _get_enabled(self):
+ enabled = self._read_channel_attr("enable")
+
+ if enabled == "1":
+ return True
+ elif enabled == "0":
+ return False
+
+ raise PWMError(None, "Unknown enabled value: \"{:s}\"".format(enabled))
+
+ def _set_enabled(self, value):
+ if not isinstance(value, bool):
+ raise TypeError("Invalid enabled type, should be bool.")
+
+ self._write_channel_attr("enable", "1" if value else "0")
+
+ enabled = property(_get_enabled, _set_enabled)
+ """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}, chip {:d} (period={:f} sec, duty_cycle={:f}%, polarity={:s}, enabled={:s})" \
+ .format(self._channel, self._chip, self.period, self.duty_cycle * 100, self.polarity, str(self.enabled))
\ No newline at end of file
projects / Adafruit_Blinka-hackapet.git / blobdiff