Merge pull request #890 from lurch/patch-1

Prevent negative light values
gpiozero · Mar 1, 2021 · 7949f49 · 7949f49
2 parents a9850a8 + 54f8a7c
commit 7949f49
Showing 1 changed file with 5 additions and 5 deletions.
diff --git a/gpiozero/input_devices.py b/gpiozero/input_devices.py
@@ -723,18 +723,18 @@ def _read(self):
         self.pin.function = 'output'
         self.pin.state = False
         sleep(0.1)
-        # Time the charging of the capacitor
-        start = self.pin_factory.ticks()
         self._charge_time = None
         self._charged.clear()
+        # Time the charging of the capacitor
+        start = self.pin_factory.ticks()
         self.pin.function = 'input'
         self._charged.wait(self.charge_time_limit)
         if self._charge_time is None:
             return 0.0
         else:
-            return 1.0 - (
-                self.pin_factory.ticks_diff(self._charge_time, start) /
-                self.charge_time_limit)
+            return 1.0 - min(1.0, 
+                (self.pin_factory.ticks_diff(self._charge_time, start) /
+                self.charge_time_limit))
 
     @property
     def value(self):