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<file>
;
; MIOS Custom LCD Driver Example for character LCDs
;
; NOTE:	this is just a template for LCDs which are different to 
;       HD44780 (that is natively supported by MIOS -> LCD type #0)
;       Note also that this driver only supports a single CLCD
;       and no free definable enable (E) line
;
; ==========================================================================
;
;  Copyright (C) 2003  Thorsten Klose (tk@midibox.org)
;  Licensed for personal non-commercial use only.
;  All other rights reserved.
; 
; ==========================================================================

;; --------------------------------------------------------------------------
;;  Following system variables are given by MIOS and can be directly 
;;  accessed by the driver. The addresses are defined in mios.h and
;;  should not be changed
;; 
;;  MIOS_GLCD_BUFFER	     a 8 byte buffer for data transfers
;;  MIOS_LCD_OPTION1	     contains the first LCD option given by MIOS_LCD_TypeSet
;;  MIOS_LCD_OPTION2	     contains the second LCD option given by MIOS_LCD_TypeSet
;;  MIOS_LCD_CURSOR_POS	     the current cursor pos of characters (GLCD: multiplied by width)
;;  MIOS_GLCD_GCURSOR_X	     for GLCDs: the current X position of graphical cursor
;;  MIOS_GLCD_GCURSOR_Y	     for GLCDs: the current Y position of graphical cursor
;;  MIOS_GLCD_FONT_WIDTH     for GLCDs: the fontwidth given by MIOS_GLCD_FontInit
;;  MIOS_GLCD_FONT_HEIGHT    for GLCDs: the fontheight given by MIOS_GLCD_FontInit
;;  MIOS_GLCD_FONT_X0        for GLCDs: the first byte within a char entry
;;  MIOS_GLCD_FONT_OFFSET    for GLCDs: the byte offset between the characters
;;  MIOS_GLCD_FONT_PTRL      for GLCDs: pointer to the character table, low-byte
;;  MIOS_GLCD_FONT_PTRH      for GLCDs: pointer to the character table, high-byte
;;  MIOS_LCD_TIMEOUT0        can be used for timeout loops
;;  MIOS_LCD_TIMEOUT1        can be used for timeout loops
;;  MIOS_GLCD_TMP1           can be used as temporary buffer
;;  MIOS_GLCD_TMP2           can be used as temporary buffer
;;  MIOS_GLCD_TMP3           can be used as temporary buffer
;;  MIOS_GLCD_TMP4           can be used as temporary buffer
;;  MIOS_LCD_Y0_OFFSET       Y0 offset of LCD
;;  MIOS_LCD_Y1_OFFSET       Y1 offset of LCD
;;  MIOS_LCD_Y2_OFFSET       Y2 offset of LCD
;;  MIOS_LCD_Y3_OFFSET       Y3 offset of LCD
;;  MIOS_LCD_CURSOR_POS_REAL unmapped cursor position which has been set with MIOS_LCD_CursorSet
;; 
;;  Note: the addresses are located in an upper bank and therefore have to
;;        be accessed with the BANKED flag. Also the BSR has to be justified
;;        before using the registers
;;  Example:
;;	SET_BSR MIOS_LCD_OPTION1	; sets BSR to the bank where MIOS_LCD_*
;;					; has been located. You don't need to
;;					; change the BSR for the other LCD registers
;;      movf    MIOS_LCD_OPTION1, W, BANKED	; get LCD option #1
;; 
;;  Important: to allow a proper interaction with MIOS applications, you are
;;  only allowed to modify MIOS_PARAMETER[123], the mutliplication registers
;;  and FSR1. You are not allowed to change TMP[1-5] or FSR0
;;  if you need some temporary registers, use the given addresses above or
;;  locate them to addresses which are not used by the application
;; --------------------------------------------------------------------------

;; Pins of LC-Display
USER_LCD_LAT_D		EQU	LATB	; Pin B.7-0
USER_LCD_PORT_D	EQU     PORTB
USER_LCD_TRIS_D	EQU     TRISB

USER_LCD_LAT_RW	EQU     LATD
USER_LCD_PIN_RW	EQU     6               ; Pin D.6
USER_LCD_LAT_RS	EQU     LATD
USER_LCD_PIN_RS	EQU     5               ; Pin D.5

USER_LCD_LAT_E	EQU     LATD		; Pin D.7
USER_LCD_PIN_E	EQU     7

;; new names for CLCD registers
USER_LCD_STATUS		EQU	MIOS_GLCD_TMP1
USER_LCD_SC_CTR		EQU	MIOS_GLCD_TMP3

#define USER_LCD_STATUS_LCD0_DISABLED	0	; bit0:	if set, first LCD disabled
#define USER_LCD_STATUS_LCD1_DISABLED	1	; bit1:	if set, second LCD disabled -- not provided by this driver!
#define USER_LCD_STATUS_CUR_DISABLED	2	; bit2:	if set, currently selected LCD disabled
#define USER_LCD_STATUS_CUR_LCD		3	; bit3: if cleared: current LCD is first LCD, else second LCD

;; --------------------------------------------------------------------------
;;  This function is called by MIOS when the custom LCD should be initialized
;;  In:  MIOS_LCD_OPTION1 - contains the first LCD option given by MIOS_LCD_TypeSet
;;       MIOS_LCD_OPTION2 - contains the second LCD option given by MIOS_LCD_TypeSet
;;  Out: -
;; --------------------------------------------------------------------------
USER_LCD_Init
	;; notify that no graphical LCD is connected
	bcf	MIOS_BOX_CFG0, MIOS_BOX_CFG0_USE_GLCD

	movlw	0xf9		; set only TRISE[2:1] as output
	andwf	TRISE, F

	; (Initialization of Ports: done in Init_Ports)
	SET_BSR	MIOS_LCD_TIMEOUT1
	clrf	USER_LCD_STATUS, BANKED

	movlw	100			; 100 ms delay
	call	MIOS_Delay

        bcf     USER_LCD_LAT_RW, USER_LCD_PIN_RW	; LCD_WRITE
        bcf     USER_LCD_LAT_RS, USER_LCD_PIN_RS	; USER_LCD_PIN_RS_0

	;; initialize LCD
	movlw	0x38
	movwf	USER_LCD_LAT_D
	rcall	USER_LCD_Strobe_Set
	rcall	USER_LCD_Strobe_Clr
	movlw	50			; 50 ms delay
	call	MIOS_Delay
	rcall	USER_LCD_Strobe_Set
	rcall	USER_LCD_Strobe_Clr
	movlw	50			; 50 ms delay
	call	MIOS_Delay
	rcall	USER_LCD_Strobe_Set
	rcall	USER_LCD_Strobe_Clr

	movlw	0x08			; Display Off
	rcall	USER_LCD_Cmd
	movlw	0x0c			; Display On
	rcall	USER_LCD_Cmd
	movlw	0x06			; Entry Mode
	rcall	USER_LCD_Cmd
	movlw	0x01			; Clear Display
	call	USER_LCD_Cmd
	bcf	MIOS_LCD_TIMEOUT1, 7, BANKED	; everything ok, make sure that LCD_TIMEOUT, bit 7 is cleared
	
	movlw	0x38			; without these lines the LCD will not work
	rcall	USER_LCD_Cmd		; correctly after a second USER_LCD_Init
	movlw	0x0c
	rcall	USER_LCD_Cmd
	movlw	0x00			; set cursor to zero pos
	rgoto	USER_LCD_CursorSet

;; --------------------------------------------------------------------------
;;  FUNCTION: USER_LCD_Data
;;  DESCRIPTION: sends a data value to the LCD display.<BR>
;;  On CLCDs: branch directly to USER_LCD_PrintChar<BR>
;;  On GLCDs: ignore this function!
;;  IN:  data which should be sent
;;  OUT: -
;; --------------------------------------------------------------------------
USER_LCD_Data
	;; store byte in data latch
	movwf	USER_LCD_LAT_D
	;; store bits 3:2 into port E bits 2:1
	rrncf 	WREG, 0, 0	;; shift right
	movwf	LATE		;; store in port E latch
	rlncf	WREG, 0, 0	;; shift left, leave WREG as it was!

	;; wait until display unbusy
	rcall	USER_LCD_WaitUnbusy

	;; exit if current LCD not available due to timeout
	BIFSET	USER_LCD_STATUS, USER_LCD_STATUS_CUR_DISABLED, BANKED, return

	;; select data register
        bsf     USER_LCD_LAT_RS, USER_LCD_PIN_RS

	;; activate write
        bcf     USER_LCD_LAT_RW, USER_LCD_PIN_RW

	;; strobe and exit
	rcall	USER_LCD_Strobe_Set
	rgoto	USER_LCD_Strobe_Clr


;; --------------------------------------------------------------------------
;;  FUNCTION: USER_LCD_Cmd
;;  DESCRIPTION: sends a command to the LCD display.<BR>
;;  On CLCDs: use this function to decode the HD44780 commands if required<BR>
;;  On GLCDs: ignore this function!
;;  IN:  command which should be sent
;;  OUT: -
;; --------------------------------------------------------------------------
USER_LCD_Cmd
	;; store byte in data latch
	movwf	USER_LCD_LAT_D
	;; store bits 3:2 into port E bits 2:1
	rrncf 	WREG, 0, 0	;; shift right
	movwf	LATE		;; store in port E latch
	rlncf	WREG, 0, 0	;; shift left, leave WREG as it was!

	;; wait until display unbusy
	rcall	USER_LCD_WaitUnbusy

	;; exit if current LCD not available due to timeout
	BIFSET	USER_LCD_STATUS, USER_LCD_STATUS_CUR_DISABLED, BANKED, return

	;; select command register
        bcf     USER_LCD_LAT_RS, USER_LCD_PIN_RS

	;; activate write
        bcf     USER_LCD_LAT_RW, USER_LCD_PIN_RW

	;; strobe and exit
	rcall	USER_LCD_Strobe_Set
	rgoto	USER_LCD_Strobe_Clr


;; --------------------------------------------------------------------------
;;  This function is NOT called by MIOS, but only used by the custom driver
;;  to wait until the LCD is unbusy
;;  In:  -
;;  Out: -
;; --------------------------------------------------------------------------
USER_LCD_WaitUnbusy
	;; exit if current LCD not available due to timeout
	BIFSET	USER_LCD_STATUS, USER_LCD_STATUS_CUR_DISABLED, BANKED, return

	;; turn off output drivers
	movlw	0xf3		; set all except TRISB[3:2] as input
	iorwf	USER_LCD_TRIS_D, F
	movlw	0x06		; set only TRISE[2:1] as input
	iorwf	TRISE, F

	;; select command register
        bcf     USER_LCD_LAT_RS, USER_LCD_PIN_RS

	;; poll busy bit
	clrf	MIOS_LCD_TIMEOUT0, BANKED
	clrf	MIOS_LCD_TIMEOUT1, BANKED

        bsf     USER_LCD_LAT_RW, USER_LCD_PIN_RW	; LCD_READ
USER_LCD_WaitUnbusy_Loop
	rcall	USER_LCD_Strobe_Clr
	incf	MIOS_LCD_TIMEOUT0, F, BANKED
	skpnz
	incf	MIOS_LCD_TIMEOUT1, F, BANKED
	bz	USER_LCD_WaitUnbusy_Disable	; leave loop when LCD_TIMEOUT = 0xff. Up to now bit 7 is set and the LCD
						; busy routine will never be called again
	rcall	USER_LCD_Strobe_Set
	IFSET	USER_LCD_PORT_D, 7, rgoto USER_LCD_WaitUnbusy_Loop
	rcall	USER_LCD_Strobe_Clr

USER_LCD_WaitUnbusy_End
	;; turn on output drivers again
	movlw	0x0c		; set all except TRISB[3:2] as output
	andwf	USER_LCD_TRIS_D, F
	movlw	0xf9		; set only TRISE[2:1] as output
	andwf	TRISE, F
	return

USER_LCD_WaitUnbusy_Disable
	;; disable currently selected LCD
	btfss	USER_LCD_STATUS, USER_LCD_STATUS_CUR_LCD, BANKED
	bsf	USER_LCD_STATUS, USER_LCD_STATUS_LCD0_DISABLED, BANKED
	btfsc	USER_LCD_STATUS, USER_LCD_STATUS_CUR_LCD, BANKED
	bsf	USER_LCD_STATUS, USER_LCD_STATUS_LCD1_DISABLED, BANKED
	rgoto	USER_LCD_WaitUnbusy_End


;; --------------------------------------------------------------------------
;;  This function is NOT called by MIOS, but only used by the custom driver
;;  to set the strobe line to logic-1
;;  In:  -
;;  Out: -
;; --------------------------------------------------------------------------
USER_LCD_Strobe_Set
	;; (code for variable E output removed)
	bsf	USER_LCD_LAT_E, USER_LCD_PIN_E
	nop
	nop
	nop
	nop
	nop
	return

;; --------------------------------------------------------------------------
;;  This function is NOT called by MIOS, but only used by the custom driver
;;  to set the strobe line to logic-0
;;  In:  -
;;  Out: -
;; --------------------------------------------------------------------------
USER_LCD_Strobe_Clr
	;; (code for variable E output removed)
	nop
	nop
	nop
	nop
	nop
	bcf	USER_LCD_LAT_E, USER_LCD_PIN_E
	return


;; --------------------------------------------------------------------------
;;  This function is called by MIOS when the custom LCD should be cleared
;;  In:  MIOS_LCD_OPTION1 - contains the first LCD option given by MIOS_LCD_TypeSet
;;       MIOS_LCD_OPTION2 - contains the second LCD option given by MIOS_LCD_TypeSet
;;  Out: -
;; --------------------------------------------------------------------------
USER_LCD_Clear
	movlw	0x01
	call	USER_LCD_Cmd
	BIFSET	MIOS_LCD_Y2_OFFSET, 7, BANKED, rgoto USER_LCD_Clear2
	BIFSET	MIOS_LCD_Y3_OFFSET, 7, BANKED, rgoto USER_LCD_Clear2
	return
USER_LCD_Clear2
	bsf	MIOS_LCD_CURSOR_POS, 7, BANKED
	movlw	0x01
	call	USER_LCD_Cmd
	bcf	MIOS_LCD_CURSOR_POS, 7, BANKED
	return

;; --------------------------------------------------------------------------
;;  This function is called by MIOS when the cursor should be changed
;;  In:  MIOS_LCD_OPTION1 - contains the first LCD option given by MIOS_LCD_TypeSet
;;       MIOS_LCD_OPTION2 - contains the second LCD option given by MIOS_LCD_TypeSet
;;       MIOS_GLCD_CURSOR_X - horizontal cursor position (for GLCDs)
;;       MIOS_GLCD_CURSOR_Y - vertical cursor position   (for GLCDs)
;;       MIOS_LCD_CURSOR_POS - character cursor position  (for CLCDs)
;;  Out: -
;; --------------------------------------------------------------------------
USER_LCD_CursorSet
	SET_BSR	MIOS_LCD_CURSOR_POS
	movf	MIOS_LCD_CURSOR_POS, W, BANKED
	iorlw	0x80
	rgoto	USER_LCD_Cmd

;; --------------------------------------------------------------------------
;;  This function is called by MIOS when a character should be print
;;  In:  WREG - character
;;       all other MIOS_*LCD_* registers
;;  Out: GLCDs should justify the X/Y cursor position
;; --------------------------------------------------------------------------
USER_LCD_PrintChar
	rgoto	USER_LCD_Data


;; --------------------------------------------------------------------------
;;  FUNCTION: USER_LCD_SpecialCharInit
;;  DESCRIPTION: see MIOS_CLCD_SpecialCharInit
;;  IN:  number of special character (0-7) in WREG
;;       pointer to special char pattern in TBLPTR (consists of 8
;;          entries for every character-line)
;;  OUT: TBLPTR has to be set to next table entry (TBLPTR+=8)
;; --------------------------------------------------------------------------
USER_LCD_SpecialCharInit
	;; transfer special character to display
	swapf	WREG, F
	rrf	WREG, W
	andlw	0x38
	iorlw	0x40
	rcall	USER_LCD_Cmd

	SET_BSR	USER_LCD_SC_CTR
	clrf	USER_LCD_SC_CTR, BANKED
USER_LCD_SpecialCharInitLoop
	tblrd*+
	movf	TABLAT, W
	rcall	USER_LCD_Data
	incf	USER_LCD_SC_CTR, F, BANKED
	BIFCLR	USER_LCD_SC_CTR, 3, BANKED, rgoto USER_LCD_SpecialCharInitLoop

	goto	USER_LCD_CursorSet
</file>
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