keep from chaining ValueErrors

[hackapet/Adafruit_Blinka.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 e7d64a0ab066510d6dbe406dc30c0b3a8476847d..d0686f71cdf3ae4b1646b690940d07ec22732e26 100644 (file)
--- a/src/adafruit_blinka/microcontroller/generic_linux/sysfs_pwmout.py
+++ b/src/adafruit_blinka/microcontroller/generic_linux/sysfs_pwmout.py
@@ -118,7 +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),
@@ -130,6 +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),
@@ -142,8 +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)
 
@@ -177,8 +189,9 @@ 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)