;============================={INFORMATION}================================== ; File: lcd.asm ; Project: PIC/lcd ; Author: Tamás Nagy ; Version: 1.00 ; Used PIC: PIC16F88A ;**************************************************************************** ;============================={DESCRIPTION}================================== ;LCD functions> ; LCD_Init - initialize LCD display ; LCD_Data - send data to LCD ; LCD_Instr - send instruction to LCD ; LCD_Clear - clear LCD ; LCD_Goto - move cursor to position ; LCD_ON - LCD ON ; LCD_OFF - LCD OFF ; LCD_Shift_Left - shift display left ; LCD_Shift_Right - shift diplay right ; LCD_Cursor_ON - cursor ON ; LCD_CBlink_ON - cursor and cursor blink ON ; LCD_CB_OFF - cursor and cursor blink OFF ; LCD_Cursor_Inc - increment cursor position after writing data ; LCD_Cursor_Dec - decrement cursor position after writing data ; LCD_Home - return home (position 0) ;**************************************************************************** ; Delay times> ; delay_100ms: ; 16MHz = 50ms ; 8MHz = 100ms -> default setting, must change the delay ; 4MHz = 200ms ; 1MHz = 400ms ; delay_1ms: ; 16MHz = 500us ; 8MHz = 1ms -> default setting, must change the delay ; 4MHz = 2ms ; 1MHz = 4ms ;**************************************************************************** ;------------------------------{DEFINITIONS}--------------------------------- #define w 0 #define f 1 ;-------------------------------{VARIABLES}---------------------------------- cblock 0x20 t,t1,t2,LCD_Temp,temp,count endc ;=================================={LCD}===================================== LCD_Init: movlw d'50' ;wait more than 15ms power time call delay_1ms movlw b'00110000' ;function set, interface is 8 bit long call LCD_Instr movlw d'20' ;wait more than 5ms call delay_1ms movlw b'00110000' ;function set, interface is 8 bit long call LCD_Instr movlw d'2' ;wait more than 100us call delay_1ms movlw b'00110000' ;function set, interface is 8 bit long call LCD_Instr movlw d'2' ;wait call delay_1ms movlw b'00100000' ;function set, interface is 4 bit long call LCD_Instr movlw d'2' ;wait call delay_1ms movlw b'00101000' ;0 0 1 DL N F - - call LCD_Instr ;DL=0 (4 bit comunication), N=1 (two lines), F=0 (font= 5x8 dots) movlw d'2' ;wait call delay_1ms movlw b'00001000' ;0 0 0 0 1 D C B call LCD_Instr ;D=0 (display off), C=0 (cursor off), B=0 (cursor blinking off) movlw d'2' ;wait call delay_1ms movlw b'00000001' ;clear display call LCD_Instr movlw d'2' ;wait call delay_1ms movlw b'00000110' ;0 0 0 0 0 1 I/D S call LCD_Instr ;I/D=1 (increment position), S=1 (display shift) movlw d'2' ;wait call delay_1ms movlw b'00001100' ;turn on display, cursor and blinking call LCD_Instr movlw d'2' ;wait call delay_1ms movlw b'00010100' call LCD_Instr return ;-----------------------------{Send LCD data}-------------------------------- LCD_Data: movwf LCD_Temp bcf LCD_D7 ;clear all data pins bcf LCD_D6 bcf LCD_D5 bcf LCD_D4 btfsc LCD_Temp,7 ;writing upper 4 bits bsf LCD_D7 btfsc LCD_Temp,6 bsf LCD_D6 btfsc LCD_Temp,5 bsf LCD_D5 btfsc LCD_Temp,4 bsf LCD_D4 bsf LCD_E fill (nop),30 bcf LCD_E bcf LCD_D7 ;clear again all data pins bcf LCD_D6 bcf LCD_D5 bcf LCD_D4 btfsc LCD_Temp,3 ;write lower 4 bits bsf LCD_D7 btfsc LCD_Temp,2 bsf LCD_D6 btfsc LCD_Temp,1 bsf LCD_D5 btfsc LCD_Temp,0 bsf LCD_D4 bsf LCD_E fill (nop),30 bcf LCD_E return ;--------------------------{Send LCD instruction}---------------------------- LCD_Instr: bcf LCD_RS ;send instruction call LCD_Data bsf LCD_RS return ;--------------------------------{LCD Clear}--------------------------------- LCD_Clear: bcf LCD_RS movlw 0x01 ;LCD clear command call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return ;--------------------------------{LCD Goto}---------------------------------- LCD_Goto: iorlw 0x80 ;LCD goto position bcf LCD_RS call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return ;--------------------------------{LCD Home}---------------------------------- LCD_Home: movlw 0x02 bcf LCD_RS call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return ;-----------------------------{LCD shift left}------------------------------- ;LCD shift instruction: 0 0 0 1 S/C R/L - - ;S/C: 0= Cursor move, 1= Display shift ;R/L: 0= Shift to the left, 1= Shift to the right LCD_Shift_Left: movwf count shiftl: movf count,w iorlw 0x00 btfsc STATUS,Z return movlw b'00011000' ;display shift to left bcf LCD_RS call LCD_Data bsf LCD_RS decf count,f movlw d'2' ;wait between shifts (100ms/shift) call delay_100ms goto shiftl ;----------------------------{LCD shift right}------------------------------- ;LCD shift instruction: 0 0 0 1 S/C R/L - - ;S/C: 0= Cursor move, 1= Display shift ;R/L: 0= Shift to the left, 1= Shift to the right LCD_Shift_Right: movwf count shiftr: movf count,w iorlw 0x00 btfsc STATUS,Z return movlw b'00011100' ;display shift to right bcf LCD_RS call LCD_Data bsf LCD_RS decf count,f movlw d'2' ;wait between shifts (100ms/shift) call delay_100ms goto shiftr ;------------------{OFF/ON DISPLAY, CURSOR, CURSOR BLINKING}----------------- ;Display instruction: 0 0 0 0 1 D C B ;Display ON/OFF bit > D: 1= ON, 0= OFF ;Cursor ON/OFF bit > C: 1= ON, 0= OFF ;Cursor blinking bit > B: 1= ON, 0= OFF LCD_ON: bcf LCD_RS movlw b'00001100' ;Disp = ON, Cursor= OFF, Blink= OFF call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return LCD_OFF: bcf LCD_RS movlw b'00001000' ;Disp = OFF, Cursor= OFF, Blink= OFF call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return LCD_Cursor_ON: bcf LCD_RS movlw b'00001110' ;Disp = ON, Cursor= ON, Blink= OFF call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return LCD_CBlink_ON: bcf LCD_RS movlw b'00001111' ;Disp = ON, Cursor= ON, Blink= ON call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return LCD_CB_OFF: call LCD_ON ;Disp = ON, Cursor= OFF, Blink= OFF return ;--------------{Cursor shift direction and Accompanies shift}--------------- ;Instruction: 0 0 0 0 0 1 I/D S ;I/D: 0= Decrement, 1= Increment ;S: 1= Accompanies display shift LCD_Cursor_Inc: iorlw b'00000110' bcf LCD_RS call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return LCD_Cursor_Dec: iorlw b'00000100' bcf LCD_RS call LCD_Data bsf LCD_RS movlw d'1' call delay_1ms return ;**************************************************************************** ;-------------------------------{DELAY 100ms}-------------------------------- delay_100ms: ;default 8MHz clock movwf t clrf t1 ;16MHz = 50ms clrf t2 ;8MHz = 100ms del: decfsz t2,f ;4MHz = 200ms goto del ;1MHz = 400ms decfsz t1,f goto del decfsz t,f goto del return ;--------------------------------{DELAY 1ms}---------------------------------- delay_1ms: ;default 8MHz clock movwf t clrf t1 ;16MHz = 500us del1: fill (nop),5 ;8MHz = 1ms decfsz t1,f ;4MHz = 2ms goto del1 ;1MHz = 4ms decfsz t,f goto del1 return ;****************************************************************************