' Title IRSerout.Bas
' @ L. Johnson  20th September 1999
'
' Send Asyncronous Serial Data over an Infra-Red Link
' At Various Baud Rates and Inverted Mode
' An Infra-Red LED should be Connected to PORTB.0
' If longer range is required and NPN transistor could be employed
' as an amplifier, as in the BASIC STAMP1 Application Notes

' Place  Include "Irserout.Bas"
' At the front of the Program to load the new subroutine in
'
' To Use the New Routine, Load the Variable:- 
' IR_ByteOut with the appropriate value (0-255)
' And Call the Subroutine:-
' Gosub IRSerout
'
' Three New Defines have been added:-
' IRSEROUT_PORT.....Selects the Port for sending (ie PORTB)
' IRSEROUT_PIN......Selects the Pin for sending (ie 1)
' IRSEROUT_BAUD.....Selects the Baud Rate (ie 300,600,1200,2400)

' IRSerout works with 4Mhz, 8Mhz, 10Mhz and 12Mhz Xtals

' *** The Subroutine is only 56 Bytes in length ***

' This routine is for the 16F84, but any 14bit core PIC could be used

' Define Variables
	Dlctr		Var	Byte		' Counter For Serial Delay Routines
	Bctr		Var	Byte		' Number Of Transmitted Bits
	Tr_B		Var	Byte		' Variable Used In Transmitter
	Ir_Byteout	Var	Byte		' Value To Be Send Out
	IR_Bit		Var	Bit		' Pulse ON or OFF 
	Dl_Temp		Var	Byte		' Counter2 For Serial Delay Routines
	ON_Delay	Var	DL_Temp
	Off_Delay	Var	DL_Temp

' ******************************
' ** Jump Over the Subroutine **
' ******************************
Goto	Over_IRSEROUT			

IRSerout:
Asm
#Define	IR_LED	IRSEROUT_PORT , IRSEROUT_PIN	;' Get the Port and Pin from the two new Defines

;' Set Defaults for IRSEROUT_PORT and IRSEROUT_PIN  to   PORTA BIT 0
	Ifndef IRSEROUT_PORT
IRSEROUT_PORT = PortA
	endif 
	Ifndef IRSEROUT_PIN
IRSEROUT_PIN = 0
	endif

;' Set Default to 1200 Baud Inverted
	Ifndef IRSEROUT_BAUD
IRSEROUT_BAUD = 1200
	endif

			
		Bcf IRSEROUT_PORT,IRSEROUT_PIN	;' Clear the appropriate pin
		Bsf Status,5			;' Set to Bank1
		Bcf IRSEROUT_PORT,IRSEROUT_PIN	;' Make the appropriate pin an Output
		Bcf Status,5			;' Back to Page 0		


;' Send out the Data serially at Various bauds, Inverted
		Mov w,_Ir_Byteout	;' Move the Value into the W register
		Clrwdt			;' Walk the Dog
		Movwf	_TR_B	
		Movlw	08
		Movwf	_Bctr		;' Eight Bits In A Byte!.
		Bsf	_IR_Bit
		Call	Send_Bit	;' Send the Start Bit at Approx 39Khz. 
SIRXmt		Rrf	_Tr_B		;' Rotate Right Moves the Data Bits Into the Carry
					;' Starting With Bit 0. 
   		Btfsc   Status,0	;' Test the Carry Flag
		Bcf	_IR_Bit		;' Send a Zero
    		Btfss   Status,0	;' Test the Carry Flag
		Bsf	_IR_Bit		;' Send A One
		Call	Send_Bit	;' Send the Data Bit at Approx 39 Khz. 
		Decfsz	_Bctr		;' Not Eight Bits Yet? Send the Next Data Bit
		Goto	SIRXmt
		Bcf	_IR_Bit		;' Set LO	
		Call	Send_Bit	;' Send the stop bit at Approx 39khz

;' Delay for X amount of time
		Clrwdt			;' Walk the Dog	
		Movlw	255					
		Movwf	_DlCtr
IRSInner	Clrwdt			;' Walk the Dog		
		Nop
		Nop
		Nop
		Nop
		Nop
		Nop
		Decfsz	_DlCtr		;' Do the Inner Loop		
		Goto	IRSInner
		Return

;' This Routine Sends a Pulse modulated at Approx 39Khz 
;' Out of the Appropriate pin within a Delay of 1 bit time

Send_Bit	
;' Assemble this code if the Baud rate is 300
	If (IRSEROUT_BAUD == 300)
		Movlw	128		;' Set the Delay Time for 300 Baud
	endif
;' Assemble this code if the Baud rate is 600
	If (IRSEROUT_BAUD == 600)
		Movlw	64		;' Set the Delay Time for 600 Baud
	endif
;' Assemble this code if the Baud rate is 1200
	If (IRSEROUT_BAUD == 1200)
		Movlw	32		;' Set the Delay Time for 1200 Baud
	endif
;' Assemble this code if the Baud rate is 2400
	If (IRSEROUT_BAUD == 2400)
		Movlw	16		;' Set the Delay Time for 2400 Baud
	endif

Pulse_Bit	Movwf	_Dlctr		;' Store it
Irlp1		Clrwdt			;' Walk The Dog
   		Btfsc   _Ir_Bit		;' If Ir_Bit=1 Then	
		Bsf	IR_LED		;' Turn the IR_Led On
    		Btfss   _Ir_Bit		;' If Ir_Bit=0 Then	
    		Bcf     IR_LED		;' Turn the IR_Led Off	

;' Assemble this code if the Xtal is 4Mhz
	if  (OSC == 4)
		Movlw	3
		Movwf	_On_Delay
Inner1		Decfsz	_On_Delay
		Goto Inner1
	endif

;' Assemble this code if the Xtal is 8Mhz
	if  (OSC == 8)
		Movlw	8
		Movwf	_On_Delay
Inner1		Decfsz	_On_Delay
		Goto Inner1
	endif

;' Assemble this code if the Xtal is 10Mhz
	if  (OSC == 10)
		Movlw	12			;' *****Not Sure Untested ***
		Movwf	_On_Delay
Inner1		Decfsz	_On_Delay
		Goto Inner1
	endif

;' Assemble this code if the Xtal is 12Mhz
	if  (OSC == 12)
		Movlw	17
		Movwf	_On_Delay
Inner1		Decfsz	_On_Delay
		Goto Inner1
	endif

		Bcf 	IR_LED		;' Turn the IR_LED Off

;' Assemble this code if the Xtal is 4Mhz
	if  (OSC == 4)
		Nop
		Nop
		Nop
		Nop
		Nop
		Nop
	endif
;' Assemble this code if the Xtal is 8Mhz
	if  (OSC == 8)
		Movlw	5
		Movwf	_Off_Delay
Inner2		Decfsz	_Off_Delay
		Goto Inner2
	endif

;' Assemble this code if the Xtal is 10Mhz
	if  (OSC == 10)
		Movlw	5
		Movwf	_Off_Delay
Inner2		Decfsz	_Off_Delay
		Goto Inner2
	endif

;' Assemble this code if the Xtal is 12Mhz
	if  (OSC == 12)
		Movlw	5
		Movwf	_Off_Delay
Inner2		Decfsz	_Off_Delay
		Goto Inner2
	endif

		Decfsz	_Dlctr
		Goto	Irlp1	
		Return

Endasm
Over_IRSEROUT: