6502-OS/system/lcd.s65

;********************************************************************************
; @module LCD-W164B
; @type driver
; @device ELECTRONIC ASSEMBLY - W164B-NLW
; @details
;   The LCD must be connected to a W65C22N Interface Chip:
;     - IO.RB0-7  -> LCD.D0-7 data lines
;     - IO.RA5    -> LCD.RS   register select
;     - IO.RA6    -> LCD.R/W  read/write
;     - IO.RA7    -> LCD.E    enable
;   
; @requires LCD_IO: Base Address of IO Chip
; @optparam LCD_MEM: Memory address for a runtime variable. Default = $300
; @depends IO-W65C22N
;********************************************************************************

    .ifndef LCD_IO
    .fatal "LCD_IO is not defined: set it to the base address of the IO chip of the LCD"
    .endif

    .ifndef INCLUDE_IOW65C22
    .error "IO-W65C22 module is not included"
    .endif

    .include "utility.h65"


; RAM VARIABLES
    .ifndef LCD_MEM
LCD_MEM = $300
    .endif
LCD_CHARCOUNT   = LCD_MEM

; PIN MASKS
LCD_E       = %10000000
LCD_RW      = %01000000
LCD_RS      = %00100000
    ; .local LCD_E,LCD_RW,LCD_RS

; LCD Instructions (see datasheet for more)
LCD_CMD_CLEAR           = %00000001  ; clear display
LCD_CMD_ENTRY_MODE      = %00000110  ; auto-shift cursor
LCD_CMD_DISPLAY_ON      = %00001111  ; everything on, with blinking cursor
LCD_CMD_FUNCTION_SET    = %00111000  ; 8-bit, 4 lines, 5x7 font
LCD_CMD_SET_ADDRESS     = %10000000  ; or with the address
; LCD Constants
LCD_LINE1      = $00
LCD_LINE2      = $40
LCD_LINE3      = $10
LCD_LINE4      = $50

LCD_CLEAR   = %00000000


;********************************************************************************
; @function Initialize the lcd module
; @details call before doing anything else
;********************************************************************************
.proc lcd_init
    ; init IO
    lda #$ff                        ; RB 0-7 output
    sta LCD_IO+IO_DDRB

    ; UT_update_with_mask LCD_IO + IO_DDRA, (LCD_RS | LCD_RW | LCD_E), (LCD_RS | LCD_RW | LCD_E)
    lda #(LCD_RS | LCD_RW | LCD_E)   ; RA 5-7 output
    sta LCD_IO+IO_DDRA

    ; init lcd
    lda #LCD_CMD_FUNCTION_SET  
    jsr _lcd_cmd
    lda #LCD_CMD_DISPLAY_ON
    jsr _lcd_cmd
    lda #LCD_CMD_CLEAR
    jsr _lcd_cmd
    lda #LCD_CMD_ENTRY_MODE
    jsr _lcd_cmd

    stz LCD_CHARCOUNT
    rts
.endproc

;********************************************************************************
; PRINTING TO LCD
;********************************************************************************

;********************************************************************************
; @function Clear the display
; @see lcd_print
;********************************************************************************
.proc lcd_clear
    stz LCD_CHARCOUNT
    lda #LCD_CLEAR
    jsr _lcd_cmd
    lda #(LCD_CMD_SET_ADDRESS | LCD_LINE1)
    jsr _lcd_cmd
    rts
.endproc

;********************************************************************************
; @function Print a null-terminated string
; @param ARG0-1 Address of the string to print
;********************************************************************************
.proc lcd_print
    ldy #$00
@lcd_print_loop:
    lda ARG0,y
    beq @lcd_print_end
    jsr _lcd_char
    iny
    bra @lcd_print_loop
@lcd_print_end:
    rts
.endproc

.macro Print message
    jsr lcd_clear
    lda #.LOBYTE(message)
    sta ARG0
    lda #.HIBYTE(message)
    sta ARG1
    jsr lcd_print
.endmacro

;********************************************************************************
; LCD Commands
;********************************************************************************
; read busy flag
_lcd_wait_nbusy:
    stz LCD_IO + IO_DDRB           ; set IO1-LCD_IO + IO_RB to input
@lcd_wait_nbusy_loop:   ; read the busy flag
    lda #LCD_RW
    sta LCD_IO + IO_RA
    lda #(LCD_RW | LCD_E)
    sta LCD_IO + IO_RA
    
    lda LCD_IO + IO_RB
    and #%10000000      ; and updates zero flag, if not set retry
    bne @lcd_wait_nbusy_loop
    
    lda #%00000000      ; TODO dont overwrite 0-4
    sta LCD_IO + IO_RA
    lda #%11111111   ; set IO1-LCD_IO + IO_RB to output
    sta LCD_IO + IO_DDRB
    rts
    
.proc _lcd_cmd            ; send cmd in acc
    pha
    jsr _lcd_wait_nbusy
    pla

    ; TODO use UT_update_with_mask?
    sta LCD_IO + IO_RB
    lda #LCD_CLEAR
    sta LCD_IO + IO_RA
    lda #LCD_E
    sta LCD_IO + IO_RA
    lda #LCD_CLEAR
    sta LCD_IO + IO_RA
    rts
.endproc

_lcd_char:
    pha
    pha
    ; TODO use UT_update_with_mask?
    jsr _lcd_wait_nbusy
    pla
    sta LCD_IO + IO_RB
    lda #LCD_RS
    sta LCD_IO + IO_RA
    lda #(LCD_RS | LCD_E) 
    sta LCD_IO + IO_RA
    lda #LCD_RS
    sta LCD_IO + IO_RA
    inc LCD_CHARCOUNT
    jsr _lcd_set_address
    pla ; put char back in a

;********************************************************************************
; Set the LCD DD-RAM Address so that text linebreaks after 16 chars
;********************************************************************************
.proc _lcd_set_address
    ; check if checks are necessary
    lda LCD_CHARCOUNT
    beq @lcd_line1
    and #%10001111  ; ($10 | $20 | $30 | $40) = %01110000
    bne @lcd_set_address_done
    ; checks necessary
    lda LCD_CHARCOUNT
    beq @lcd_line1
    cmp #$10
    beq @lcd_line2
    cmp #$20
    beq @lcd_line3
    cmp #$30
    beq @lcd_line4
    cmp #$40  ; set to line1 when full  ; set to line1 when full
    beq @lcd_line1 
@lcd_set_address_done:
    rts
@lcd_line1:
    stz LCD_CHARCOUNT
    lda #(LCD_CMD_SET_ADDRESS | LCD_LINE1)
    jsr _lcd_cmd
    rts
@lcd_line2:
    lda #(LCD_CMD_SET_ADDRESS | LCD_LINE2)
    jsr _lcd_cmd
    rts
@lcd_line3:
    lda #(LCD_CMD_SET_ADDRESS | LCD_LINE3)
    jsr _lcd_cmd
    rts
@lcd_line4:
    lda #(LCD_CMD_SET_ADDRESS | LCD_LINE4)
    jsr _lcd_cmd
    rts
.endproc