PIC16Fxxx的LCD驅動程序(適用于HD44780兼容

PIC16Fxxx的LCD驅動程序(適用于HD44780兼容的驅動器)

;************************************************
;* LCD.ASM *
;************************************************
;* Contains subroutines to control an external *
;* lcd panel in 4-bit mode. These routines *
;* were designed specifically for the panel on *
;* the MCU201 workshop demo board, but should *
;* work with other LCDs with a HD44780 type *
;* controller. *
;* Routines include: *
;* - InitLCD to initialize the LCD panel *
;* - putcLCD to write a character to LCD *
;* - SendCmd to write a command to LCD *
;* - clrLCD to clear the LCD display *
;* - L1homeLCD to return cursor to line 1 home*
;* - L2homeLCD to return cursor to line 2 home*
;* - PutHexLCD to write a HEX Code to LCD *
;* - Hex2ASCII to convert 4 bits to ASCII Code*
;************************************************
;
list p=16f877
＃i nclude p16f877.inc>
;
; Defines for I/O ports that provide LCD data control
; PORTB.0 - PORTB.3 are Data Pins for LCD Module
; PORTB.4 is E Control Signal for LCD
; PORTB.5 is RS Control Signal for LCD
; PORTC.2 is BackLight Control pin for LCD Module
;
global InitLCD
global putcLCD
global clrLCD
global L1homeLCD
global L2homeLCD
global SendCmd
global PutHexLCD
global Hex2ASCII
;
LCD_DATA equ PORTB
LCD_CNTL equ PORTB

; Defines for I/O pins that provide LCD control
RS equ 5
E equ 4

; LCD Module commands
DISP_ON EQU 0x00C ; Display on
DISP_ON_C EQU 0x00E ; Display on, Cursor on
DISP_ON_B EQU 0x00F ; Display on, Cursor on, Blink cursor
DISP_OFF EQU 0x008 ; Display off
CLR_DISP EQU 0x001 ; Clear the Display
ENTRY_INC EQU 0x006 ;
ENTRY_INC_S EQU 0x007 ;
ENTRY_DEC EQU 0x004 ;
ENTRY_DEC_S EQU 0x005 ;
DD_RAM_ADDR EQU 0x080 ; Least Significant 7-bit are for address
DD_RAM_UL EQU 0x080 ; Upper Left coner of the Display
;

; Directs linker to provide 4 variables in GPR memory
UDATA
Byte RES 1
Byte1 RES 1
Count RES 1
Count1 RES 1
W_BUFR RES 1
Hex_Bfr RES 1
;
PROG1 CODE
;*******************************************************************
;* The LCD Module Subroutines *
;* Command sequence for 2 lines of 5x16 characters *
;*******************************************************************
InitLCD
BANKSEL TRISB
movlw 0xc0 ; Initialize inputs/outputs for LCD
movwf TRISB
BANKSEL LCD_DATA
clrf LCD_DATA ; Clear LCD data control bits
;
movlw .50 ; Power=On delay 50mS
Call Delay_MS
;
movlw 0x02 ; Init for 4-bit interface
call Send_4bit
movlw .10 ; Delay 10 mS
Call Delay_MS
;
movlw b'00000011' ; Fully Initial LCD module
call Send_4bit ; Sent '0011' data 4 time
movlw .5 ; Delay 5mS
Call Delay_MS
movlw b'00000011'
call Send_4bit
call Delay_1MS ; Delay 1mS
movlw b'00000011'
call Send_4bit
movlw b'00000010'
call Send_4bit
;
movlw b'00101000' ; Set 2 lines 5 x 7 dots
call SendCmd
movlw DISP_ON ; Turn display on (0x0C)
call SendCmd
movlw ENTRY_INC ; Configure cursor movement
call SendCmd
movlw DD_RAM_ADDR ; Set writes for display memory
call SendCmd
return
;
;*******************************************************************
;*SendChar - Sends character to LCD *
;*This routine splits the character into the upper and lower *
;*nibbles and sends them to the LCD, upper nibble first. *
;*******************************************************************
putcLCD
banksel Byte
movwf Byte ; Save WREG in Byte variable
call Delay_1MS
swapf Byte,W ; Write upper nibble first
andlw 0x0f
movwf LCD_DATA
bsf LCD_CNTL, RS ; Set for data
bsf LCD_CNTL, E ; Clock nibble into LCD
bcf LCD_CNTL, E
movf Byte,W ; Write lower nibble last
andlw 0x0f
movwf LCD_DATA
bsf LCD_CNTL, RS ; Set for data
bsf LCD_CNTL, E ; Clock nibble into LCD
bcf LCD_CNTL, E
return