start implementing the new all-great tuerd

[saartuer.git] / pins.py

diff --git a/pins.py b/pins.py
new file mode 100644 (file)
index 0000000..8b699be
--- /dev/null
+++ b/pins.py
@@ -0,0 +1,71 @@
+import RPi.GPIO as GPIO
+from collections import namedtuple
+from libtuer import ThreadRepeater, logger
+from statemachine import StateMachine
+
+class PinsState():
+       pass
+
+class PinWatcher():
+       def __init__(self, pin, histlen):
+               GPIO.setup(pin, GPIO.IN)
+               assert histlen > 1 # otherwise our logic goes nuts...
+               self.pin = pin
+               self._histlen = histlen
+               # state change detection
+               self.state = None
+               self._newstate = None # != None iff we are currently seeing a state change
+               self._newstatelen = 0 # only valid if newstate != None
+       
+       def read(self):
+               curstate = GPIO.input(self.pin)
+               assert curstate in (0, 1)
+               if curstate != self._state:
+                       # the state is about to change
+                       if curstate == self._newstate:
+                               # we already saw this new state
+                               self._newstatelen += 1
+                               if self._newstatelen >= self._histlen:
+                                       # we saw it often enough to declare it the new state
+                                       self.state = curstate
+                                       self._newstate = None
+                                       return True
+                       else:
+                               # now check for how long we see this new state
+                               self._newstate = curstate
+                               self._newstatelen = 1
+               else:
+                       # old state is preserved
+                       self._newstate = None
+               return False
+
+class PinsWatcher():
+       def __init__(self, state_machine):
+               self.pins = {
+                       'bell_ringing': PinWatcher(18, 2),
+                       'door_closed': PinWatcher(8, 5),
+                       'door_locked': PinWatcher(9, 5),
+                       'space_active': PinWatcher(10, 5),
+               }
+               self._sm = state_machine
+               
+               # start a thread doing the work
+               self._t = ThreadRepeater(self._read, 0.02)
+               
+       def _read():
+               saw_change = False
+               for name in self.pins.keys():
+                       pin = pins[name]
+                       if pin.read():
+                               saw_change = True
+                               logger.debug("Pin %s changed to %d" % (name, pin.state)
+               if not saw_change: return
+               # create return object
+               pinsState = PinsState()
+               for name in self.pins.keys():
+                       setattr(pinsState, name, self.pins[name].state)
+               # send it to state machine
+               self._sm.callback(StateMachine.CMD_PINS, pinsState)
+       
+       def stop():
+               self._t.stop()