'
' Story Teller, Model 7 Gallery Controller
' Tom Jennings
'
' $Id: gal.bas,v 1.3 2003/04/25 23:47:42 tomj Exp $
'
' 
' Attached to the story teller buss, this controls the performance by using
' CTS to pause the datastream.  It powers up idle, lamp blinking, and CTS
' asserted false, stopping the performance. When the switch is pressed,
' CTS is released, and the performance starts. After a predetermined period
' (about 3 minutes) this code waits for the end of the current record
' (EOT, or a NUL indicating inter-record filler) then asserts CTS false
' to stop further performance.
' 
' Note that the hardware contains a NE555 timer. It is no longer used and
' is held reset.
' 
' NOTE: The switch is push on/push off -- not momentary, hence
' the juggling. It was chosen for it's physical characteristics.
' (In fact it's easier to use than a momentary -- no missed
' presses, and it remembers it's own last state!)
'
' 25 Apr 2003
'	Serial code brought up to snuff.
'
' 27 Nov 2002
' 	Rewrote simplified code to eliminate the hardware
'	timer and hangs waiting for idle.
'
' mru 21 Sep 99
'	Changed so that CTS is dropped after every character read.
'	I really need to find a UART chip!
'
'mru 20 Sep 99
'	Added DISCHARGE delay after every reset, since the huge
'	timing cap takes ~50 mS to discharge.

' new 17 Sep 1999

symbol	swlast= bit8				' last state of the switch
symbol	c= b3					' returned serial character
symbol	serflag= b4				' char-ready flag for serinp()
symbol	timer= w3				' per-state cycle timer
symbol	ltimer= w4				' state 2 local loop counter

' PICSTIC I/O pin assignments
symbol	RXD= 7					' serial data in pin #
symbol	CTSpin= pin6				' CTS pin
symbol	CTS= 6					' CTS pin
symbol	SWpin= pin5				' bit front panel switch
symbol	LAMPpin= pin4				' lamp in switch
symbol	LAMP= 4					' lamp in switch

' These are no longer used.
symbol	TRIG= 3					' 555 trigger (0=trig)
symbol	TOUTpin= pin2				' 555 timer output
symbol	RESET= 1				' 555 timer reset (0=reset)
symbol	RESETpin= pin1
symbol	DISCHARGE= 150				' 555 large C discharge time 
						' (was measured at 50mS)

symbol	TINCR1= 1500				' IDLE: lamp blink time,
symbol	TINCR2= 3				' RUNNING: run time, minutes,

symbol	SPEED= N2400

symbol	NUL= 0					' paper tape NUL, 
symbol	SOH= 1					' start of header
symbol	STX= 2					' start of text (data)
symbol	ETX= 3					' end of text (data)
symbol	EOT= 4					' end of transmission,
symbol	ENQ= 5


'	       76543210
	dirs= %01011010				' set directions,
	pins= %00001010				' set initial states,
	RESETpin= 1				' disable 555,
	call serini				' init the serial junk,

'
' STATE 1: IDLE. Turn timer off, flash the lamp,
' wait for switch press.
'
state1:	LAMPpin= 0			' lamp is off,
	swlast= SWpin			' seed "current switch"

s1a:	timer= TINCR1			' lamp-blink timer,
s1b:	if SWpin <> swlast then state2	' go start when switch pressed,
	timer= timer - 1		' else wait,
	if timer <> 0 then s1b		' and blink the lamp,
	toggle LAMP			' 
	goto s1a

'
' STATE 2: RUNNING. Release CTS, start timing. 
'
state2:	LAMPpin= 0			' lamp off,
	swlast= SWpin			' remember current switch,
	timer= TINCR2			' start (outer loop) timer,
	CTSpin= 1			' release CTS,

s2a:	ltimer= 599			' 1 minute inner loop (minus o'head!)
s2b:	if SWpin <> swlast then state2	'     retrigger if switch pressed,
	pause 100			' 10th sec/600th minute,
	ltimer = ltimer - 1 
	if ltimer <> 0 then s2b
	timer = timer - 1 : if timer <> 0 then s2a

'
' STATE 3: WAIT FOR END OF RECORD. Look for an EOT or
' a NUL indicating the current record has ended. This
' will wait forever, however the PTR spews NULs when
' on and idle or in error.
'
state3:	call serinp			' look for a character,
	if serflag = 0 then state3	' 
	if c = EOT then state1		' end of record,
	if c = NUL then state1		' end of record,
	LAMPpin= 1 			' DEBUG
	goto state3			' wait.



ASM


;
; Poll for a serial character, returns serflag=1 and character in C
; and CTS 0 if one is present (eg. start bit visible on serial line). 
;
_serinp	clrf _serflag			; set serflag false,
	bsf portB, _CTS			; assert CTS,
	btfss portB, _RXD		; if start bit not present,
	goto done			; exit now.

	call serin@W			; read character,
	bcf portb, _CTS			; deassert CTS,
	movwf _c			; store W in C,
	bsf _serflag, 0			; set serflag
	goto done


; Ready the args for the later serin() call.

_serini	bcf portB, _CTS			; deassert CTS,
	movlw _RXD			; Rx pin number,
	call BP@Pin
	movlw _SPEED			; port speed,
	movwf GOP			; (local to ass'y code?)
	clrf _serflag			;
	goto done



ENDASM

	end