midterm2_q2.bs2

'{$STAMP BS2}
'{$PBASIC 2.5}

Setup:
	tau VAR WORD 
	counter VAR WORD 
	time VAR WORD 
	tau_threshold VAR WORD 

Main:
	tau_threshold = 200
	time = 0
	HIGH 8 
	'train stops for 5 seconds 
	FOR counter = 1 TO 100:
		GOSUB Check_Tau
		IF (tau > tau_threshold) THEN 
			GOSUB Passenger_Detected
		ENDIF 
		PAUSE 47
	NEXT 
	GOSUB No_Passenger_Detected
	END 

' stages ------------
Passenger_Detected:
	DEBUG "passenger" 
	LOW 8 
	DO WHILE (IN1 = 0)
		TOGGLE 11
		PAUSE 50
	LOOP
	GOSUB No_Passenger_Detected 
	RETURN 

No_Passenger_Detected:
	DEBUG "no passenger", CR
	time = 0
	LOW 11
	LOW 8 
	FOR counter = 1 TO 40:
		TOGGLE 10
		PAUSE 50 
	NEXT 
	GOSUB Forward 
	RETURN 

Forward:
	DEBUG "forward", CR
	time = 0
	LOW 10
	LOW 11
	FOR counter = 1 TO 150:
		GOSUB Forward_Pulse
	NEXT
	END 	
	RETURN 

' subroutines --------
Check_Tau:
	HIGH 0
	PAUSE 3 
	RCTIME 0, 1, tau
	DEBUG DEC tau, HOME, CR 
	RETURN 

Forward_Pulse:
  PULSOUT 13, 850
  PULSOUT 12, 650
  PAUSE 20
  RETURN