Merge pull request #162 from makermelissa/master

[Adafruit_Blinka-hackapet.git] / src / adafruit_blinka / microcontroller / generic_linux / sysfs_pwmout.py

diff --git a/src/adafruit_blinka/microcontroller/generic_linux/sysfs_pwmout.py b/src/adafruit_blinka/microcontroller/generic_linux/sysfs_pwmout.py
index 4c975c37e0e7acce335bc2a724c352978013de94..fa7266710cbec98c61b5772757e11a29f0a5437c 100644 (file)
--- a/src/adafruit_blinka/microcontroller/generic_linux/sysfs_pwmout.py
+++ b/src/adafruit_blinka/microcontroller/generic_linux/sysfs_pwmout.py
@@ -55,16 +55,13 @@ class PWMOut(object):
         self._open(pin, duty_cycle, frequency, variable_frequency)
 
     def __del__(self):
-        self.close()
+        self.deinit()
 
     def __enter__(self):
         return self
 
     def __exit__(self, t, value, traceback):
-        self.close()
-
-    def deinit(self):
-        self.close()
+        self.deinit()
 
     def _open(self, pin, duty=0, freq=500, variable_frequency=False):
         self._channel = None
@@ -93,12 +90,12 @@ class PWMOut(object):
         except IOError as e:
             raise PWMError(e.errno, "Exporting PWM pin: " + e.strerror)
 
-        self._set_enabled(False)
+        #self._set_enabled(False) # This line causes a write error when trying to enable
 
         # Look up the period, for fast duty cycle updates
         self._period = self._get_period()
 
-        self.duty_cycle = 0
+        #self.duty_cycle = 0  # This line causes a write error when trying to enable
 
         # set frequency
         self.frequency = freq
@@ -107,8 +104,8 @@ class PWMOut(object):
 
         self._set_enabled(True)
 
-    def close(self):
-        """Close the sysfs PWM."""
+    def deinit(self):
+        """Deinit the sysfs PWM."""
         if self._channel is not None:
             self.duty_cycle = 0
             try:
@@ -121,7 +118,15 @@ class PWMOut(object):
         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),
@@ -133,6 +138,9 @@ class PWMOut(object):
             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),
@@ -145,8 +153,9 @@ class PWMOut(object):
     # Mutable properties
 
     def _get_period(self):
+        period_ns = self._read_pin_attr(self._pin_period_path)
         try:
-            period_ns = int(self._read_pin_attr(self._pin_period_path))
+            period_ns = int(period_ns)
         except ValueError:
             raise PWMError(None, "Unknown period value: \"%s\"" % period_ns)
 
@@ -170,6 +179,8 @@ class PWMOut(object):
         # 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:
@@ -180,8 +191,9 @@ class PWMOut(object):
     """
 
     def _get_duty_cycle(self):
+        duty_cycle_ns = self._read_pin_attr(self._pin_duty_cycle_path)
         try:
-            duty_cycle_ns = int(self._read_pin_attr(self._pin_duty_cycle_path))
+            duty_cycle_ns = int(duty_cycle_ns)
         except ValueError:
             raise PWMError(None, "Unknown duty cycle value: \"%s\"" % duty_cycle_ns)