-- *********************************
-- *** Robosapien IR-OUT control ***
-- *********************************
-- ***   Created by Mark Craig   ***
-- *********************************
--   Filename: 		saplib2.jal	
--   Date: 		09/04/2005	
--   File Version: 	v1.0	
--   Written by: 	Mark Craig (*)	
--   Homepage:		http://homepages.strath.ac.uk/~lau01246	
--   Project :		Robosapien	
--   Function: 		take control of robosapien through original PCB	
-- 			 by sending IR commands directly to the PCB (as 	
-- 			 opposed to the IR-receiver). 						
-- 			 also receives IR from remote.						

--    (*): The delays are created using the following address:		
-- 	Generated by http://www.golovchenko.org/cgi-bin/delay (January 1, 2002 version) 
-- 	See also various delay routines at http://www.piclist.com/techref/microchip/delays.htm 	

--    (C): You are free to copy, use, distribute etc. but give credit where due.	

-- 	var volatile bit ir_in_pin         is pin_a0 
-- 	var volatile bit ir_out_pin        is pin_a3 

--	Modified for use with JAL compiler
--	 the send_sap is just the assembler whereas the read_sap is mostly JAL.
--       send_sap is pseudo but read_sap isn't, eg:
--	 send_sap = 0h81 will send h'81' to robosapien's IR-OUT pin
--	 read_sap( XYZ ) will return the IR code from the remote to var XYZ


-- *** Send routine, sends command through ir_out_pin to robosapien's PCB ***

procedure send_sap'put( byte in txreg ) is
var byte bitcount, d1, d2
assembler
	local	send_loop, DelayX, DelayX_0, DelayX_1, done

	movlw	0h_08 			; 8 bits of data
	movwf	bitcount		; a counter for bits
	bcf	ir_out_pin		; Low (start bit)	PORTA,3
					; for 8/1200s	
	movlw	0d_16
	call	Delayx


send_loop:
	rlf	txreg, f		; roll leftmost bit into carry		
	bsf	ir_out_pin		; high			PORTA,3	

	movlw	0d_2		; 1/1200
	btfsc	0h0003,0d00		; if carry = 0 skip, 	STATUS,C			
	movlw	0d_8		; 4/1200
	call	Delayx
	bcf	ir_out_pin		; low			PORTA,3

	movlw	0d_2
	call	Delayx
	decfsz	bitcount, f		; one less data bit, skip when 0	
	goto	send_loop		; more bits left, delay this one	
	bsf	ir_out_pin		; Stop high.		PORTA,3
	goto	done

DelayX:
	movwf	d2

DelayX_0:
			;409 cycles
	movlw	0x_88
	movwf	d1
DelayX_1:
	decfsz	d1, f
	goto	DelayX_1

			;2 cycles
	nop
	nop

			;4 cycles (including call)
	decfsz	d2, f
	goto	DelayX_0
	return

done:
end assembler
end procedure


--; *** Read IR ***

procedure alarm_triggered( byte in command_rec ) is
--	if command_rec != 0 then -- this is already checked before alarm_triggered is called
--		send_sap = command_rec
		send_sap = master_command_program_ex
--	end if
end procedure

procedure find_start is
  while( ir_in_pin == on ) loop
	read_from_pic( pic_clock_command )
	if ( pic_clock_command != 0 ) then
		alarm_triggered( pic_clock_command )
	end if
	delay_10us( 1 )	-- 10us delay
  end loop
end procedure

procedure find_fall( byte out timetaken ) is -- find falling edge and return time taken in 100's of uS
  timetaken = 0
  while( ir_in_pin == on ) loop
	timetaken = timetaken + 1
	delay_10us( 5 )	-- 50us delay
  end loop
end procedure

procedure find_rise( byte out timetaken ) is -- find rising edge and return time taken in 100's of uS
  timetaken = 0
  while( ir_in_pin == off ) loop
	timetaken = timetaken + 1
	delay_10us( 5 )	-- 50us delay
  end loop
end procedure

procedure read_sap( byte out command ) is -- read command from IR
var byte time_fall, time_rise
find_start		-- wait for start of transmission ( and check for commands from pic clock )
delay_10us( 1 )			-- give it a little time to settle
find_rise( time_rise )		-- start bit is low for 8/1200s
delay_10us( 1 )			-- give it a little time to settle
 if ( time_rise > 55 & time_rise < 65 ) then
  -- we have the start of a command on IR
  for 8 loop	-- 8 bits in a byte
    find_fall( time_fall )	-- look at length of on pulse. denotes bit: 1/1200s for 0, 4/1200s for 1
    if ( time_fall < 16 ) then	-- which side of 2/1200 is it?
					-- we have a 0 bit
	assembler
	  bcf	0h0003,0d00		; carry = 0	STATUS,C
	  rlf	command, f		; rotate carry into command
	end assembler
    else
					-- we have a 1 bit
	assembler
	  bsf	0h0003,0d00		; carry = 1	STATUS,C
	  rlf	command, f		; rotate carry into command
	end assembler
    end if
    find_rise( time_rise )	-- this should be 1/1200s but for simplicity is ignored
  end loop
 else
    command = 0h55		-- error value
	-- as only values from 0x80 to 0xFF are valid.
 end if
end procedure

-- 1/1200s is 0.000833333s or 833us or 8 x 100us
-- 4/1200s is 0.003333333s or 3333us or 33 x 100us
-- 8/1200s is 0.006666666s or 6666us or 66 x 100us

-- Timing based on 1/1200 second clock (~.833ms)
-- Signal is normally high (idle, no IR).
-- Start: signal goes low for 8/1200 sec.
-- Data bits: for each of 8 data bits, space encoded signal depending on bit value
--     Sends the most significant data bit first
--     If the data bit is 0: signal goes high for 1/1200 sec, and low for 1/1200 sec.
--     If the data bit is 1: signal goes high for 4/1200 sec, and low for 1/1200 sec.
--     BTW: The first bit (msb) is always 1 (valid codes are from $80 to $FF)
-- When completed, signal goes high again.
-- No explicit stop bit. Minimal between signals is not known.