'reading a PIR (passive infrared) sensor

pirPin PIN 0			'input pin
pirState VAR BIT		'current state of pin (0 or 1)
pirStatePrev VAR BIT	'previous value
pirCount VAR BYTE		'count of how many cycles pirPin has been HIGH

INPUT 0				'make pin an input

top:
pirState = pirPin		'read pin
IF pirState = 1 THEN
	pirCount = pirCount + 1		'if HIGH, increment count
ENDIF
IF pirState <> pirStatePrev THEN	'if state has changed
	pirStatePrev = pirState		'record current state
	DEBUG "state: ",DEC pirState
	IF pirState = 0 THEN			'if pin has gone LOW, reset count
		DEBUG " cycles ON: ",DEC pirCount
	ENDIF
	DEBUG CR
ENDIF
GOTO top

'  CIRCUIT:
'
'  __PIR___
'  |  |   |
' GND V+ OUT
'  |  |   |
'  | +5v  |---INPUT_PIN
'  |      |
'  |-----10k_ohm
'  |
' GND