Added comments to device classes

lib/Device/Display/Pcd8544Device.php

@@ -32,6 +32,7 @@ class Pcd8544Device extends Device
             ->addLogicalPin(1, "sce", "chip select")
             ->addLogicalPin(2, "scl", "clock")
             ->addLogicalPin(3, "sda", "data")
+            ->addLogicalPin(4, "res", "reset")
             ->addLogicalPin(9, "bl", "backlight")
             ;
     }
@@ -43,6 +44,6 @@ class Pcd8544Device extends Device
     
     public function setBacklightState($state)
     {
-        $this->bl->write((int)$state);
+        $this->bl->setValue((bool)$state);
     }
 }