PIC16Fxxx的LCD驅動程序(適用于HD44780兼容
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;
;*********************************************************************
;* To put the HEX value to LCD Display ,,
;* High nibble first than Low nibble
;* Input : W Reg.
;*********************************************************************
PutHexLCD
banksel W_BUFR
movwf W_BUFR ; Save W Register !!
swapf W_BUFR,W ; High nibble first !!
call Hex2ASCII
call putcLCD
;
movf W_BUFR,W
call Hex2ASCII
call putcLCD
return
;
;******************************************************************
;* Convert a low nibble to ASCII code
;* Input : W Reg.
;* Output: W Reg.
;******************************************************************
Hex2ASCII
andlw 0x0f ; Mask Bit 4 to 7
movwf Hex_Bfr
sublw .09
btfsc STATUS,C ; If W less than A (C=1) --> only add 30h
goto Add_W_30
Add_W_37 movlw 0x37
goto Hex_cont
Add_W_30 movlw 0x30
Hex_cont addwf Hex_Bfr,W ; The correct ASCII code for this char !!
return
;
;*******************************************************************
;* SendCmd - Sends command to LCD *
;* This routine splits the command into the upper and lower *
;* nibbles and sends them to the LCD, upper nibble first. *
;*******************************************************************
SendCmd
banksel Byte
movwf Byte ; Save WREG in Byte variable
call Delay_1MS
swapf Byte,W ; Send upper nibble first
andlw 0x0f
movwf LCD_DATA
bcf LCD_CNTL,RS ; Clear for command
bsf LCD_CNTL,E ; Clock nibble into LCD
bcf LCD_CNTL,E
movf Byte,W ; Write lower nibble last
Send_4bit andlw 0x0f
movwf LCD_DATA
bcf LCD_CNTL,RS ; Clear for command
bsf LCD_CNTL,E ; Clock nibble into LCD
bcf LCD_CNTL,E
return
;
;*******************************************************************
;* clrLCD - Clear the contents of the LCD *
;*******************************************************************
clrLCD
movlw CLR_DISP ; Send the command to clear display
call SendCmd
return
;
;*******************************************************************
;* L1homeLCD - Moves the cursor to home position on Line 1 *
;*******************************************************************
L1homeLCD
movlw DD_RAM_ADDR|0x00 ; Send command to move cursor to
call SendCmd ; home position on line 1
return本文引用地址：http://www.104case.com/article/150736.htm
;*******************************************************************
;* L2homeLCD - Moves the cursor to home position on Line 2 *
;*******************************************************************
L2homeLCD
movlw DD_RAM_ADDR|0x28 ; Send command to move cursor to
call SendCmd ; home position on line 2
return
;*******************************************************************
;* Delay - Generic LCD delay (1.024mS @ 4MHz) *
;* Since the microcontroller can not read the busy flag of the *
;* LCD, a specific delay needs to be executed between writes to *
;* the LCD. *
;*******************************************************************
Delay_1MS ; 2 cycles for call
clrf Count ; 1 cycle to clear counter variable
Dloop
nop
decfsz Count,F ; These two instructions provide a
goto Dloop ; (256 * 3) -1 cycle count
return ; 2 cycles for return
;
;*******************************************************************
;* Delay - 1mS base delay *
;* input : W Reg. *
;* *
;*******************************************************************
Delay_MS
movwf Count1
;
DLop1 call Delay_1MS
decfsz Count1,F
goto DLop1
return
;
END
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