; WRITTEN BY PETER BIRNIE
; COPYRIGHT P. B. MICRO DESIGNS - 01494 531709
; DATE 11.8.95
; ITERATION 1.0
; FILE SAVED AS DOTLCD.ASM
; FOR PIC16C74-04/P WDT=off CP=off
; CLOCK 4.00 MHz RESONATOR
; INSTRUCTION CLOCK 1.00 MHz T= 1us
TITLE "DOTLCD.asm - LCD dot matrix driver and string handler"
LIST P=16C74
;----------------------------------------------------------------------------
; Program handle all aspects of setup and display on a dot matrix lcd
; display. Routines are provided to allow display of strings or
; characters, place the cursor and clear the display.
;----------------------------------------------------------------------------
; Register File Assignment
;----------------------------------------------------------------------------
INCLUDE "P16Cxx.INC"
;----------------------------------------------------------------------------
; Physical Port Assignment
;----------------------------------------------------------------------------
LCDPORT EQU RA ; Port A - LCD
;----------------------------------------------------------------------------
; Physical Bit Assignment
;----------------------------------------------------------------------------
; A port assignment
LCDRS EQU 4 ; Lcd register select output
LCDEN EQU 5 ; Lcd enable output
;----------------------------------------------------------------------------
; Constant Assignment
;----------------------------------------------------------------------------
MEMBAS EQU 20h ; Base address of user file registers
CLKR EQU 100h ; Roll over value for rtc - subtract count
; value from this to preset count down time.
DIV256 EQU %00000111 ; 256us prescale setting
; LCD commands
LCDCLER EQU %00000001 ; Clears display, resets curcor
LCDCM EQU %10000000 ; Sets cursor using bits 0 - 6
; Line 1 range - 0 to .15
; Line 2 range - .40 to .55
; NOTE that subroutine LCDCUR2 take the
; value in W in range 0 - 15 and adjusts for
; line 2 offset.
;----------------------------------------------------------------------------
; Variable Assignment
;----------------------------------------------------------------------------
GP1 EQU MEMBAS ; General purpose register
; LCD variables here
STRNUM EQU GP1+1
CHPT EQU STRNUM+1 ; Character string pointer in string.
LCDCH EQU CHPT+1 ; Saves byte to be sent to lcd while
; it is processed.
TABOFF EQU LCDCH+1 ; Table ofset pointer in lcd string lookup
;--------------------------------------------------------------------------
; Macros
;--------------------------------------------------------------------------
;******
; CLKLCD clocks data/command to the lcd by making the EN line
; high then low.
CLKLCD MACRO
SETB LCDPORT.LCDEN ; Lcd enable LOW
CLRB LCDPORT.LCDEN ; Lcd enable HIGH
ENDM
;******
; TABSET sets up the lcd table offset pointer before string output
; starts
TABSET MACRO
MOV W, #%11111111 ; Offset is incremented on each call to
; table - first call must generate zero value
; offset.
MOV TABOFF, W
ENDM
;******
; POINT increments the string pointer offset and adds it to the
; PLC ready for string lookup
POINT MACRO
INC TABOFF
MOV W, TABOFF
ADD PC, W
ENDM
;******
; POINT8 increments the string pointer offset and adds it to the
; PLC ready for string lookup. Sets PCLATH to 8
POINT8 MACRO
MOV W, #8
;*** WARNING: PCLATH register bits are in STATUS PAx bits. Or use PAGE/IREAD if possible
; MOVWF PCLATH
MOV PCLATH, W
INC TABOFF
MOV W, TABOFF
ADD PC, W
ENDM
;******
; POINT9 increments the string pointer offset and adds it to the
; PLC ready for string lookup. Sets PCLATH to 9
POINT9 MACRO
MOV W, #9
;*** WARNING: PCLATH register bits are in STATUS PAx bits. Or use PAGE/IREAD if possible
; MOVWF PCLATH
MOV PCLATH, W
INC TABOFF
MOV W, TABOFF
ADD PC, W
ENDM
;******
; TSTRTC moves TIMER0 to W reg and sets ZERO status
TSTRTC MACRO
MOV W, RTCC ; Test for timeout
ENDM
;******
; BANK0 selects register file bank 0
BANK0 MACRO
CLRB STATUS.RP0 ; Select BANK 0
ENDM
;******
; BANK1 selects register file bank 1
BANK1 MACRO
SETB STATUS.RP0 ; Select BANK 1
ENDM
;******
; PAGE0 selects rom page 0
PAGE0 MACRO
;*** WARNING: PCLATH register bits are in STATUS PAx bits. Or use PAGE/IREAD if possible
; BCF PCLATH,3 ; Select rom page 0
CLRB PCLATH.3 ; Select rom page 0
ENDM
;******
; PAGE1 selects rom page 1
PAGE1 MACRO
;*** WARNING: PCLATH register bits are in STATUS PAx bits. Or use PAGE/IREAD if possible
; BSF PCLATH,3 ; Select rom page 1
SETB PCLATH.3 ; Select rom page 1
ENDM
;--------------------------------------------------------------------------
; Vectors
;--------------------------------------------------------------------------
;******
; Reset vector
ORG 000
JMP INIT ; Do a cold start on power up
;******
; Interrupt vector - timer, keypad
ORG 004
JMP INIT ; No interrupt so reset
;--------------------------------------------------------------------------
; Subroutines
;--------------------------------------------------------------------------
;******
; STRING sends the string with number in W register - to the lcd
STRING
MOV STRNUM, W
TABSET ; Xero the offset
PAGE1
CALL DOSTR ; Character from string
PAGE0 ; Restore rom page
RET
;******
; BCDLCD sends the bcd character in W to lcd
BCDLCD OR W, #'00110000' ; Convert to ascii
;******
; PUTLCD sends the ASCII character in W to lcd
PUTLCD
MOV LCDCH, W
PAGE1
CALL CHALCD ; Character to lcd
PAGE0 ; Restore rom page
RET
;******
; CUR1 and CUR2 are indirect subroutine calls to LCDCUR1/2
; Enter with character placement in W in range 0 - 15
CUR1
PAGE1
CALL LCDCUR1 ; Line 1 please
PAGE0
RET
CUR2
PAGE1
CALL LCDCUR2 ; Line 2 please
PAGE0
RET
;******
; LCDCLR is an indirect call to LCDCLR1 on page 1
LCDCLR
PAGE1
CALL LCDCLR1
PAGE0
RET
;******
; WAITGP waits for the number of ms in GP1
WAITGP MOV W, #CLKR-4 ; 1ms timeout in TIMER0
MOV RTCC, W
WAITGPA TSTRTC
;*** WARNING: MPASM macro BNZ is not supported yet. Replace manually.
BNZ WAITGPA ; Wait for rtc to time out
DEC GP1
;*** WARNING: MPASM macro BNZ is not supported yet. Replace manually.
BNZ WAITGP ; Loop until delay is complete
RET ; Exit from WAITGP
;--------------------------------------------------------------------------
; Setup
;--------------------------------------------------------------------------
;*** WARNING: PCLATH register bits are in STATUS PAx bits. Or use PAGE/IREAD if possible
;INIT CLRF PCLATH
INIT CLR PCLATH
;******
;
; Set up peripheral control registers.
; Set port data directions: unused port pins set to outputs.
; A port setup
; Outputs
; RA0 - 3 lcd data
; RA4 lcd register select
; RA5 lcd enable
CLR LCDPORT
BANK1
MOV W, #%00000111 ; Select port A as digital
MOV ADCON1, W
MOV W, #%00000000 ; Set port data directions
;*** WARNING: TRIS registers are accessed by MOV !Rx, W (M = $0F or $1F).
; MOVWF TRISA
MOV TRISA, W
BANK0
;******
; Set up timer options
; Timer0 is set for internal, 1/4 ms pre scale
MOV W, #DIV256 ; Set RTC0 for 1/4 ms tick
BANK1
;*** WARNING: OPTION register is accessed only by MOV !OPTION, W.
; MOVWF OPTION_REG
MOV OPTION_REG, W
BANK0
;******
; Reset the lcd
INITA MOV W, #20 ; Delay for 20 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000011 ; Reset
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #6 ; Delay to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000011 ; Reset
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000011 ; Reset
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000010 ; 4 bit interface
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000010 ; 4 bit interface
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #%00001000 ; 2 LINES, 5*7
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000000 ; Display OFF
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #%00001000 ;
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000000 ; Display clear
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #%00000001 ;
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000000 ; Entry mode set
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #%00000110 ;
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
MOV W, #%00000000 ; Display on
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #%00001100 ;
MOV LCDPORT, W ; Command to lcd port
CLKLCD ; Clock the nibble to the lcd
MOV W, #5 ; Delay for 5 ms to let lcd settle
MOV GP1, W
CALL WAITGP ; Wait for lcd
;--------------------------------------------------------------------------
; Program start
;--------------------------------------------------------------------------
; Display demonstration banner
IDLE
CALL LCDCLR ; Not really required here as display has
; just been set up!
MOV W, #3
CALL CUR1 ; Position text on line 1
MOV W, #1 ; 'Microchip' - NOTE that the string is on
; second page of ROM at 0X800.
CALL STRING
; Move cursor for line 2 of banner
MOV W, #0
CALL CUR2 ; Position text on line 2
MOV W, #3 ; '16C74 drives lcd' - NOTE that the string
; is on second page of ROM at 0x900.
CALL STRING
IDLE1 JMP IDLE1 ; Just loop here please
;--------------------------------------------------------------------------
; Second page of ROM
;--------------------------------------------------------------------------
; Text strings and control subroutines must be stored on the correct
; page or this pcogram WILL NOT FUNCTION CORRECTLY.
; Only move code around if you are absoluteley clear as to what you
; are doing!
ORG $800
LAST EQU %10000000 ; Value to add to last character in a string
;******
; DOSTR uses CALLSTR table to direct flow to the correct lookup table
; for lcd strings. Gets string characters and outputs to lcd
DOSTR
MOV W, #8
;*** WARNING: PCLATH register bits are in STATUS PAx bits. Or use PAGE/IREAD if possible
; MOVWF PCLATH ; Keep the pageing ok
MOV PCLATH, W ; Keep the pageing ok
MOV W, STRNUM ; Get the string number
CALL CALLSTR
MOV LCDCH, W
CALL CHALCD ; Character to lcd
SB LCDCH.7 ; Test if end of string flagged - bit 7 set
JMP DOSTR ; Loop until all sent
RET
;******
; CALLSTR is the dispatch table for lcd string lookup
CALLSTR ADD PC, W
NOP
JMP MSG1 ; 'Microchip'
JMP MSG2 ; 'On page 9'
; more jumps can be added here
JMP MSG3 ; '16C74 drives lcd'
;******
; THE TEXT STRINGS!
MSG1 POINT8 ; Use macro POINT8 when the string is in 0x800
; address area
RETW #'M'
RETW #'i'
RETW #'c'
RETW #'r'
RETW #'o'
RETW #'c'
RETW #'h'
RETW #'i'
RETW #'p'+LAST
MSG2 POINT8
RETW #'O'
RETW #'n'
RETW #' '
RETW #'P'
RETW #'a'
RETW #'g'
RETW #'e'
RETW #' '
RETW #'8'+LAST
ORG $900
MSG3 POINT9 ; Use macro POINT9 when the string is in 0x900
; address area
RETW #'1'
RETW #'6'
RETW #'C'
RETW #'7'
RETW #'4'
RETW #' '
RETW #'d'
RETW #'r'
RETW #'i'
RETW #'v'
RETW #'e'
RETW #'s'
RETW #' '
RETW #'l'
RETW #'c'
RETW #'+LAST
;--------------------------------------------------------------------------
; Subroutines to handle the lcd
;--------------------------------------------------------------------------
; NOTE: these must be on page 1 of rom
; ------------------------------------
;*****
; CHALCD writes the character in W register to the lcd.
; On entry, the display character is in LCDCH.
CHALCD
; Get the upper nibble and load to the lcd port
MOV W, <>LCDCH ; Get the ms nibble to ls position
AND W, #07H ; Strip to ms nibble in ls position,
; and mask top bit in case this is the lset
; character in a string
MOV LCDPORT, W ; Data to lcd port
SETB LCDPORT.LCDRS ; Select lcd data
; Clock the ms nibble to the lcd
CLKLCD
; Get the lower nibble and load to the lcd port
MOV W, LCDCH ; Get back the character
AND W, #0FH ; Strip to ms nibble in ls position
MOV LCDPORT, W ; Data to lcd port
SETB LCDPORT.LCDRS ; Select lcd data
; Clock the ls nibble to the lcd.
CLKLCD
CLRB LCDPORT.LCDRS
JMP LCD64 ; Delay then exit from CHALCD
;*****
; COMLCD writes the command in W register to the lcd
; On entry, the command character is in LCDCH.
COMLCD
; Get the upper nibble and load to the lcd port
MOV W, <>LCDCH ; Get the ms nibble to ls position
AND W, #0FH ; Strip to ms nibble in ls position
MOV LCDPORT, W ; Command to lcd port
; Clock the ms nibble to the lcd
CLKLCD
; Get the lower nibble and load to the lcd port
MOV W, LCDCH ; Get back the character
AND W, #0FH ; Strip to ms nibble in ls position
MOV LCDPORT, W ; Command to lcd port
; Clock the ls nibble to the lcd.
CLKLCD
JMP LCD2 ; Delay then exit from COMLCD
;******
; LCDCL1R clears the display and resets the cursor
LCDCLR1 MOV W, #LCDCLER ; LCD clear command
MOV LCDCH, W
JMP COMLCD
;******
; LCDCUR1 sets cursor to position on line 1 using value in W register
LCDCUR1 OR W, #LCDCM ; Cursor move command
MOV LCDCH, W
JMP COMLCD
;******
; LCDCUR2 sets cursor to position on line 2 using value in W register
LCDCUR2 OR W, #LCDCM ; Cursor move command
MOV LCDCH, W
SETB LCDCH.6 ; This bit set for line 2
JMP COMLCD
;******
; LCD64/2 gives a delay of 64us or 1.6ms while the lcd accepts the
; data or command.
; Uses TMR0 - prescale is set to 16us in OPTION.
LCD64 MOV W, #CLKR-3 ; Gives 48/64 us delay
JMP LCDEL
LCD2 MOV W, #CLKR-100 ; Gives 1.6ms delay
LCDEL MOV RTCC, W ; Set TMR0 prescalar
LCDELA TSTRTC
;*** WARNING: MPASM macro BNZ is not supported yet. Replace manually.
BNZ LCDELA ; Wait for TMR0 to time out
RETW #0 ; Exit from CHA/COMLCD routines
END
| file: /Techref/scenix/lib/io/dev/lcd/dotlcd_sx.htm, 15KB, , updated: 2000/6/29 14:46, local time: 2024/11/23 03:58,
3.138.32.53:LOG IN
|
| ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://massmind.org/techref/scenix/lib/io/dev/lcd/dotlcd_sx.htm"> scenix lib io dev lcd dotlcd_sx</A> |
| Did you find what you needed? |
Welcome to massmind.org! |
Welcome to massmind.org! |
.