+"""PWMOut Class for NXP LPC4330"""
+
+from greatfet import GreatFET
+from greatfet.interfaces.pattern_generator import PatternGenerator
+
+try:
+ from microcontroller.pin import pwmOuts
+except ImportError:
+ raise RuntimeError("No PWM outputs defined for this board")
+
+from microcontroller.pin import Pin
+
+
+# pylint: disable=unnecessary-pass
+class PWMError(IOError):
+ """Base class for PWM errors."""
+ pass
+
+
+# pylint: enable=unnecessary-pass
+class PWMOut:
+ """Pulse Width Modulation Output Class"""
+
+ MAX_CYCLE_LEVEL = 1024
+
+ def __init__(self, pin, *, frequency=750, duty_cycle=0, variable_frequency=False):
+ """This class makes use of the GreatFET One's Pattern Generator to create a
+ Simulated Pulse width modulation. The way that the Pattern Generator works is that
+ takes a pattern in the form of bytes and will repeat the output. The trick to simulate
+ PWM is to generate the correct byte pattern for the correct channel.
+
+ 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)
+
+ 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._gf = GreatFET()
+
+ if variable_frequency:
+ raise NotImplemented("Variable Frequency is not currently supported.")
+
+ self._pattern = None
+ self._channel = None
+ self._enable = False
+ self._open(pin, duty_cycle, frequency)
+
+ def __enter__(self):
+ return self
+
+ def __exit__(self, t, value, traceback):
+ self.deinit()
+
+ def _open(self, pin, duty=0, freq=500):
+ self._channel = None
+ for pwmpair in pwmOuts:
+ if pwmpair[1] == pin:
+ self._channel = pwmpair[0]
+
+ self._pin = pin
+ if self._channel is None:
+ raise RuntimeError("No PWM channel found for this Pin")
+
+ # set duty
+ self.duty_cycle = duty
+
+ # set frequency
+ self.frequency = freq
+
+ self._set_enabled(True)
+
+ def deinit(self):
+ """Deinit the GreatFET One PWM."""
+ # pylint: disable=broad-except
+ try:
+ if self._channel is not None:
+ # self.duty_cycle = 0
+ self._set_enabled(False)
+ except Exception as e:
+ # due to a race condition for which I have not yet been
+ # able to find the root cause, deinit() often fails
+ # but it does not effect future usage of the pwm pin
+ print(
+ "warning: failed to deinitialize pwm pin {0} due to: {1}\n".format(
+ self._channel, type(e).__name__
+ )
+ )
+ finally:
+ self._pattern = None
+ self._channel = None
+ # pylint: enable=broad-except
+
+ def _is_deinited(self):
+ if self._pattern is None:
+ raise ValueError(
+ "Object has been deinitialize and can no longer "
+ "be used. Create a new object."
+ )
+
+ # Mutable properties
+
+ def _get_period(self):
+ return 1.0 / self._get_frequency()
+
+ def _set_period(self, 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
+ """
+ if not isinstance(period, (int, float)):
+ raise TypeError("Invalid period type, should be int or float.")
+
+ self._set_frequency(1.0 / period)
+
+ period = property(_get_period, _set_period)
+
+
+ def _get_duty_cycle(self):
+ """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
+ """
+ return self._duty_cycle
+
+ 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.")
+
+ # convert from 16-bit
+ if isinstance(duty_cycle, int):
+ duty_cycle /= 65535.0
+ if not 0.0 <= duty_cycle <= 1.0:
+ raise ValueError("Invalid duty cycle value, should be between 0.0 and 1.0.")
+
+ # Generate a pattern for 1024 samples of the duty cycle
+ pattern = [(1 << self._channel)] * round(PWMOut.MAX_CYCLE_LEVEL * duty_cycle)
+ pattern += [(0 << self._channel)] * round(PWMOut.MAX_CYCLE_LEVEL * (1.0 - duty_cycle))
+
+ self._pattern = pattern
+ self._duty_cycle = duty_cycle
+ if self._enable:
+ self._set_enabled(True)
+
+ duty_cycle = property(_get_duty_cycle, _set_duty_cycle)
+
+ def _get_frequency(self):
+ return int(PWMOut._nova.getIOpinPWMFreq(self._pwmpin).split("PWMFREQ ")[1])
+
+ def _set_frequency(self, 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
+ """
+ if not isinstance(frequency, (int, float)):
+ raise TypeError("Invalid frequency type, should be int or float.")
+
+ # We are sending 1024 samples per second already
+ self._gf.pattern_generator.set_sample_rate(frequency * len(self._pattern))
+
+ frequency = property(_get_frequency, _set_frequency)
+
+ def _get_enabled(self):
+ enabled = self._enable
+
+ if enabled == "1":
+ return True
+ if enabled == "0":
+ return False
+
+ raise PWMError(None, 'Unknown enabled value: "%s"' % enabled)
+
+ def _set_enabled(self, value):
+ """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
+ """
+ if not isinstance(value, bool):
+ raise TypeError("Invalid enabled type, should be string.")
+ self._enable = value
+ if self._gf:
+ if self._enable:
+ if self._pattern:
+ self._gf.pattern_generator.scan_out_pattern(self._pattern)
+ else:
+ self._gf.pattern_generator.stop()
projects / Adafruit_Blinka-hackapet.git / commitdiff