X-Git-Url: https://git.ayoreis.com/Adafruit_Blinka-hackapet.git/blobdiff_plain/cc3f8eccf2dda19777ed270a956d5fc8f201628d..824d525493acfb26728ca74e183417e4a58aaa23:/src/adafruit_blinka/microcontroller/am335x/sysfs_pwmout.py

diff --git a/src/adafruit_blinka/microcontroller/am335x/sysfs_pwmout.py b/src/adafruit_blinka/microcontroller/am335x/sysfs_pwmout.py
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+# 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"
+    _unexport_path = "unexport"
+    _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.deinit()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, t, value, traceback):
+        self.deinit()
+
+    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._channel,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)
+
+        # 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
+
+        self._set_enabled(True)
+
+    def deinit(self):
+      try:
+        """Deinit the sysfs PWM."""
+        channel_path = os.path.join(self._sysfs_path, self._channel_path.format(self._channel))
+        pin_path = os.path.join(channel_path, self._pin_path.format(self._channel,self._pwmpin))
+ 
+        if self._channel is not None:
+            #self.duty_cycle = 0
+            self._set_enabled(False) # make to disable before unexport
+            try:
+                #unexport_path = os.path.join(channel_path, self._unexport_path)
+                with open(os.path.join(channel_path, self._unexport_path), "w") as f_unexport:
+                    f_unexport.write("%d\n" % self._pwmpin)
+            except IOError as e:
+                raise PWMError(e.errno, "Unexporting PWM pin: " + e.strerror)
+      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}:{1} due to: {2}\n".format(self._channel, self._pwmpin, type(e).__name__))
+      finally:
+          self._channel = None
+          self._pwmpin = None
+
+    def _is_deinited(self):
+        if self._pwmpin is None:
+            raise ValueError("Object has been deinitialize and can no longer "
+                             "be used. Create a new object.")
+
+    def _write_pin_attr(self, attr, value):
+        # Make sure the pin is active
+        self._is_deinited()
+
+        path = os.path.join(
+            self._sysfs_path,
+            self._channel_path.format(self._channel),
+            self._pin_path.format(self._channel,self._pwmpin),
+            attr)
+
+        with open(path, 'w') as f_attr:
+            f_attr.write(value + "\n")
+
+    def _read_pin_attr(self, attr):
+        # Make sure the pin is active
+        self._is_deinited()
+
+        path = os.path.join(
+            self._sysfs_path,
+            self._channel_path.format(self._channel),
+            self._pin_path.format(self._channel,self._pwmpin),
+            attr)
+
+        with open(path, 'r') as f_attr:
+            return f_attr.read().strip()
+
+    # Mutable properties
+
+    def _get_period(self):
+        period_ns = self._read_pin_attr(self._pin_period_path)
+        try:
+            period_ns = int(period_ns)
+        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)
+
+    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 or float.
+
+    :type: int, float
+    """
+
+    def _get_duty_cycle(self):
+        duty_cycle_ns = self._read_pin_attr(self._pin_duty_cycle_path)
+        try:
+            duty_cycle_ns = int(duty_cycle_ns)
+        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):
+        if not isinstance(duty_cycle, (int, float)):
+            raise TypeError("Invalid duty cycle type, should be int or float.")
+
+        # convert from 16-bit
+        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.")
+
+        # 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,)