diff --git a/Lib/PIR.py b/Lib/PIR.py
new file mode 100644
index 0000000..9dd11c5
--- /dev/null
+++ b/Lib/PIR.py
@@ -0,0 +1,67 @@
+#Passive infrared motion sensor.
+
+import pyb
+
+class PIR(object):
+  """Passive Infrared Motion Sensor driver.  Supports on/off through an output pin
+     trigger reading as well as an interrupt callback on trigger high/low changes."""
+
+  def __init__(self, power, trigger, callback = None):
+    """Power and trigger pins, optional interrupt callback in the format
+       of fun( bOnOff ).  This will be called whenever the trigger state
+       changes."""
+    self._power = pyb.Pin(power, pyb.Pin.OUT_PP)
+    self._power.low()
+    self._trigger = pyb.Pin(trigger, pyb.Pin.IN, pyb.Pin.PULL_DOWN)
+    self.interrupt = callback
+
+  def _on( self, aTF ) :
+    """Turn device on/off"""
+    if (aTF):
+      oldon = self.inton
+      self.inton = False  #Make sure interrupt is off while turning on power to avoid false callbacks.
+      self._power.high()
+      if (oldon):
+        pyb.delay(200)     #Need to wait a bit after turning on to make sure we don't get false values.
+        self.inton = oldon
+    else:
+      self._power.low()
+
+  @property
+  def on(self): return self._power.value()
+
+  @on.setter
+  def on(self, value): self._on(value)
+
+  @property
+  def trigger(self): return self._trigger.value()
+
+  @property
+  def interrupt(self): return self._interrupt
+
+  @interrupt.setter
+  def interrupt(self, func):
+    self._interrupt = None;
+    self._func = func
+    if (aFunc != None):
+      self._interrupt = pyb.ExtInt(self._trigger, pyb.ExtInt.IRQ_RISING_FALLING, pyb.Pin.PULL_DOWN, self._inthandler)
+      self._inton = True
+
+  def _inthandler(self, aLine):
+    '''Function to handle interrupts and pass on to callback with on/off trigger state.'''
+       call
+    if (self._func != None):
+      self._func(self.trigger)
+
+  @property
+  def inton(self): return self._inton
+
+  @inton.setter
+  def inton(self, value):
+    self._inton = value
+    if self._interrupt != None:
+      if value :
+        self._interrupt.enable()
+      else:
+        self._interrupt.disable()
+