;                                I2CM.ASM
;***************************************************************************
;*  Listing du 09/05/2002                                                  *
;* Permet au PIC16F84 de communiquer sur un bus i2c en tant que composant  *
;* Maitre                                                                  *
;*                                                                         *
;*                              m6m                                        *
;*                             (o o)                                       *
;*                  <======oOO==(_)==OOo======>                            *
;*                                                                         *
;***************************************************************************

	List P=16c84
	Include p16c84.inc

;--------------- Equivalents utilis‚s pour la transmition i2c -------------
;_I2CM_sda             EQU     0       ;Ligne RB0/INT , ligne de donnée du bus I2C
;_I2CM_scl             EQU     1       ;Ligne RB1 , Ligne d'horloge du bus I2C

;ifndef INDF
;	#include "pic16F876"
;endif

IFNDEF _RAM
	vars equ 0ch
	_RAM	equ vars
	_RAM1	equ vars+1
	_RAM2	equ vars+2
	_RAM3	equ vars+3
	_RAM4	equ vars+4
	_RAM5	equ vars+5
	_RAM6	equ vars+6
	_RAM7	equ vars+7
	_FLAGS equ vars+8
ENDIF

_I2CM_Control	equ	_RAM	; Port number (0-2).
_I2CM_EEADRH	equ	_RAM1	; Port number (0-2).
_I2CM_EEADRL	equ	_RAM2	; Port number (0-2).
_I2CM_EEDATA	equ	_RAM3	; Port number (0-2).
_I2CM_pin_sda	equ	_RAM4	; Pin number (0-7).
_I2CM_pin_scl	equ	_RAM5	; Pin number (0-7).
_I2CM_port	equ	_RAM6	; Port number (0-2).
_I2CM_RCVSTAT	equ	7	; _Flags last byt rx/tx
_I2CM_R/W	equ	6	; _Flags R/W
_I2CM_ACQ	equ	4	; _Flags Acquit


_I2CM_INIT
	bcf	STATUS,RP1		; bank 0
	bcf	STATUS,RP0		; bank 0
	bcf	_FLAGS, _I2CM_RCVSTAT	; dele last byte flag

	MOVF	_I2CM_pin_scl,w
	ANDLW	7
	CALL	_Pinz			; Get bit mask from the table.
	MOVWF	_I2CM_pin_scl	; Put the mask into pin.
	MOVF	_I2CM_pin_sda,w
	ANDLW	7
	CALL	_Pinz			; Get bit mask from the table.
	MOVWF	_I2CM_pin_sda	; Put the mask into pin.

	MOVLW	5h			; Add offset for port RA.
	ADDWF	_I2CM_port,f
	movf	_I2CM_port,w


; suprimer car sur le 876 OPTION_REG est en bank1
;	movwf	FSR
;	sublw	6			; test if Portb
;	btfsc	STATUS,z		; if yes then
;	bcf	OPTION_REG,7	; make sure weak pull-up is on
	
	movlw	080h
	iorwf	FSR,f		; set bank 1 (Indexed Mode)
	comf	_I2CM_pin_scl,w	; make scl as an output
	andwf	INDF,f
	movlw	07fh
	andwf	FSR,f		; set bank 0 (Indexed Mode)
	return

;
; - read modified to do sequential read
;
;######################################################
;	EEPROM READ/WRITE ROUTINE
;######################################################
;		Used reg: EEADRL, EEDATA,RCVSTAT,W
;		IN  : W= READ ADRESS
;		OUT : W= BYTE

_I2CM_R/W_EE
	 	MOVWF	_I2CM_EEADRL		; store byte in reg EEADR
		movf	_I2CM_port,w
		movwf	FSR

_I2CM_R/W_EE_DIR
		CALL	_I2CM_BSTART	; generate start bit
		BCF	STATUS,CY		; WRITE SEQUENCE
		CALL	_I2CM_CONTROL_BYT ; CALC CONTROL BYTE AND TRANSMIT
; 24C16 ou PCF8583
;		MOVF	_I2CM_EEADRH,W 	;GET WORD high ADRESS
;		CALL	_I2CM_TX		;WRITE @ ADRESS COUNTER
		MOVF	_I2CM_EEADRL,W 	; get word low address....
_I2CM_R/W_EE1
		CALL	_I2CM_TX		; and send it
;		btfsc	_FLAGS,_I2CM_RCVSTAT	;if lastbyte then
;		GOTO	_I2CM_BSTOP		;  END READ SEQUENCE
		return

_I2CM_R/W_CURRENT
		CALL	_I2CM_BSTART	; generate start bit
		BSF	STATUS,CY		; READ SEQUENCE
		btfss	_FLAGS,_I2CM_R/W	; Test if R or W
		BCF	STATUS,CY		; Write SEQUENCE
		CALL	_I2CM_CONTROL_BYT ; CALC CONTROL BYTE AND TRANSMIT
		btfsc	_FLAGS,_I2CM_R/W	; Test if R or W
		GOTO	_I2CM_RX		; read 1 byte from serial EE
		GOTO	_I2CM_TX		; write 1 byte to serial EE

;
;**********************************************
;	GENERATE CONTROL BYTE
;**********************************************
_I2CM_CONTROL_BYT
		movf	_I2CM_port,w
		movwf	FSR
		RLF	_I2CM_EEADRH,W	; => CY=1
		ANDLW	B'00000001'		; Keep just R/W bit 
		IORWF	_I2CM_control,w	; Complet with control
;		ANDLW	B'00001111'     ;MASK OUT UPPER NIBBLE
;		IORLW	B'10100000'     ;COMPLETE BYTE 1010AAAD
						;A=ADRESS D=DIRECTION

						;SEND CONTROL BYTE

;**********************************************
;	TRANSMIT DATA SUBROUTINE
;**********************************************

_I2CM_TX
		MOVWF	_I2CM_EEDATA	;STORE BYTE TO TX
_I2CM_TX2
		movlw	080h
		iorwf	FSR,f		; set bank 1 (Indexed Mode)
		comf	_I2CM_pin_sda,w	; sda = 0
		andwf	INDF,f		; set data,clock as outputs
		movlw	07fh		; set bank 0 (Indexed Mode)
		andwf	FSR,f

		CALL	_I2CM_TX4		;TRANSMIT 8 TIMES
		CALL	_I2CM_TX4
		call	_I2CM_BItAcq	;	_I2CM_BITIN
		return

_I2CM_TX4
		CALL	_I2CM_TXLP
		CALL	_I2CM_TXLP
		CALL	_I2CM_TXLP
_I2CM_TXLP
	 	RLF	_I2CM_EEDATA,F	; ROTATE BIT TO CARRY
		goto	_I2CM_BITOUT_R	; send the bit to serial EE

;**********************************************
;	RECEIVE DATA SUBROUTINE
;**********************************************
_I2CM_RX 		
		movf	_I2CM_port,w
_I2CM_RX2	
		movwf	FSR
		movlw	080h
		iorwf	FSR,f		; set bank 1 (Indexed Mode)
		MOVF	_I2CM_pin_sda,w	; Get the pin mask.
		IORWF	INDF,f	; make SDATA an input line/SCLK = OU
		movlw	07fh		; set bank 0 (Indexed Mode)
		andwf	FSR,f
		CALL	_I2CM_RX4
		CALL	_I2CM_RX4

;		btfss	_FLAGs,_I2CM_RCVSTAT	; if not last byte then
		bcf	STATUS,CY		;   set Ack=0
		btfsc	_FLAGs,_I2CM_RCVSTAT	; else
		BSF	STATUS,CY		;   SET ACK BIT=0 Ack OK
		GOTO	_I2CM_BITOUT	; TO FINISH TRANSMISSION

_I2CM_RX4
		CALL	_I2CM_RXLP
		CALL 	_I2CM_RXLP
		CALL	_I2CM_RXLP

_I2CM_RXLP
		CALL	_I2CM_BITIN_R	; READ A BIT
	 	RLF	_I2CM_EEDATA,F	; SHIFT CARRY TO BYTE
   		RETURN



;*********************************************
;	START BIT SUBROUTINE
;*********************************************

_I2CM_BSTART
		movf	_I2CM_port,w
		movwf	FSR
		MOVF	_I2CM_pin_sda,w	; Get the pin mask.
		IORWF	INDF,f		; make sure data is high
		comf	_I2CM_pin_sda,w	; sda = 0
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF
		movlw	080h
		iorwf	FSR,f		; set bank 1 (Indexed Mode)
		andwf	INDF,f		; set data and clock lines for output
		movlw	07fh
		andwf	FSR,f		; set bank 0 (Indexed Mode)
		MOVF	_I2CM_pin_scl,w	; Get the pin mask.
		IORWF	INDF,f		; set clock high
		comf	_I2CM_pin_sda,w
		andwf	INDF,f		; data line goes low during
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF
		GOTO	_I2CM_BC_END	; high clock for start bit



;**********************************************
;	STOP BIT SUBROUTINE
;**********************************************


_I2CM_BSTOP
		comf	_I2CM_pin_sda,w
		andwf	INDF,f		; make sure data line is low
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		movlw	080h
		iorwf	FSR,f		; set bank 1 (Indexed Mode)
		comf	_I2CM_pin_sda,w
		andwf	INDF,f 		; set data/clock lines as outputs
		movlw	07fh
		andwf	FSR,f		; set bank 0 (Indexed Mode)
		MOVF	_I2CM_pin_scl,w	; Get the pin mask.
		IORWF	INDF,f		; set clock line high
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		MOVF	_I2CM_pin_sda,w	; Get the pin mask.
		IORWF	INDF,f		; data goes high while clock high
						; for stop bit
_I2CM_B_END
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

;		NOP
_I2CM_BC_END
		comf	_I2CM_pin_scl,w
		andwf	INDF,f		; set clock low again
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		RETURN



;**********************************************
;	BITOUT ROUTINE , SEND BIT WHEN CARRY SET
;**********************************************

_I2CM_BITOUT
		movlw	080h
		iorwf	FSR,f		; set bank 1 (Indexed Mode)
		comf	_I2CM_pin_sda,w	; sda =0
		andwf	INDF,f		; set data,clock as outputs
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		movlw	07fh
		andwf	FSR,f		; set bank 0 (Indexed Mode)
_I2CM_BITOUT_R
		BTFSc	STATUS,CY	; check for state of data bit to xmit
		goto	_I2CM_BITOUT_R1

		comf	_I2CM_pin_sda,w	; SDA  = 0
		andwf	INDF,f		; set data line low
		goto	_I2CM_CLKOUT
_I2CM_BITOUT_R1
		MOVF	_I2CM_pin_sda,w	; Get the pin clk mask.
		IORWF	INDF,f		; high? set data line high

_I2CM_CLKOUT
		MOVF	_I2CM_pin_scl,w	; Get the pin clk mask.
		IORWF	INDF,f		;  set bit.
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		GOTO	_I2CM_B_END

;**********************************************
;	BITIN ROUTINE
;**********************************************
_I2CM_BITIN
		movlw	080h
		iorwf	FSR,f		; set bank 1 (Indexed Mode)
		movf	_I2CM_pin_sda,w	; make SDATA an input line/SCLK = OUT
		iorwf	INDF,f
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		movlw	07fh
		andwf	FSR,f		; set bank 0 (Indexed Mode)
_I2CM_BITIN_R
		MOVF	_I2CM_pin_scl,w	; Get the pin clk mask.
		IORWF	INDF,f		; set clock line high
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		movf	INDF,w		; read the port
		ANDWF	_I2CM_pin_sda	; mask the data bit
		BSF	 STATUS,CY		; assume input bit is high
		BTFSc	 STATUS,z		; Test if the data bit = 0
		BCF	 STATUS,CY		; Yes, input bit was low ,clear CARRY
		GOTO	 _I2CM_BC_END
;**********************************************
;	BITAcq ROUTINE
;**********************************************
_I2CM_BItAcq
		clrf	_I2CM_EEADRH	; 255 loop for test Ack OK
		movlw	080h
		iorwf	FSR,f		; set bank 1 (Indexed Mode)
		movf	_I2CM_pin_sda,w	; make SDATA an input line/SCLK = OUT
		iorwf	INDF,f
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		movlw	07fh
		andwf	FSR,f		; set bank 0 (Indexed Mode)
_I2CM_BITIN_R
		MOVF	_I2CM_pin_scl,w	; Get the pin clk mask.
		IORWF	INDF,f		; set clock line high
		movf	INDF,w		; read the port
		ANDWF	_I2CM_pin_sda	; mask the data bit
		BSF	 STATUS,CY		; assume input bit is high
		BTFSc	 STATUS,z		; Test if the data bit = 0
		goto	_I2CM_ACKOK
		IFDEF X20MHZ
			call    Wait_10
		ENDIF
		IFNDEF X20MHZ
			call    Wait_04
		ENDIF

		decf	_I2CM_EEADRH,f
		btfss	status,Z
		goto	_I2CM_BITIN_R
_I2CM_NoACK
		BSF	 STATUS,CY		; Yes, input bit was low ,clear CARRY
		GOTO	 _I2CM_BC_END
		
_I2CM_ACKOK
		BCF	 STATUS,CY		; Yes, input bit was low ,clear CARRY
		GOTO	 _I2CM_BC_END

Wait_10 
;	pour 4Mhz
;	nop
;	nop
	call	Wait_02		; pour 20Mhz
	goto    Wait_08
Wait_08 
	call	Wait_04
	goto    Wait_04
Wait_06 
	call	Wait_02
	goto    Wait_04
Wait_04 
;	return ; pour 4Mhz
nop
nop
;nop
;nop
;nop
;nop
;nop
;nop
;nop
;nop
Wait_02
;nop
;nop
;nop
;nop
;nop
nop
return