Отправлено Сергей Борщ 21 марта 2002 г. 13:05 В ответ на: А не поделится кто-нибудь примерчиком программы на асме сопряжения MSP430 c HD44780? отправлено Albatros 20 марта 2002 г. 16:30

Связь по 4-битной шине. По 8-битной будет даже проще.

#include	
	NAME	char_lcd
#define	XTAL	4000000		; Hz
#define	ms	*XTAL/4/1000
#define	mks	*XTAL/4/1000000
#define	LCDPort	P1OUT_		; bits <7-4> to LCD D<7-4>
				; D<3-0> pulled low in LCD internaly
#define	_RS	(1<<3)		; bit <3> to LCD RS pin
#define	_E	(1<<2)		; bit <2> to LCD E pin
	PUBLIC  InitLCD		;void InitLCD(void);
	PUBLIC	WriteChar	;void WriteChar(char Char);
        PUBLIC  WriteLCDCommand	;void WriteLCDCommand(char Command);
        PUBLIC  WriteString	;void WriteString(char *String);
	PUBLIC	Delay		;void Delay(unsigned int Time);
	PUBLIC	ClearScreen	;void ClearScreen(void);
	RSEG	CODE
InitLCD:
	BIC.B	#_RS,&LCDPort
	MOV	#50 ms,R12
	CALL	#Delay
;assume display can be here in unknown (8-bit or 4-bit) mode 
;3 states possible here:
;(1) 8-bit mode
;(2) 4-bit mode waiting for higher nibble
;(3) 4-bit mode waiting for lower nibble
	MOV.B	#0x30,R12
;data reconized as:
;(1)"set 8-bit mode" command	->	DL=8,LINES=1,FONT=5*7
;(2)"set 8-bit mode" command higher nibble (*)	->	DL=8
;(3)"dummy", lower nibble of previous command
	CALL	#OutNibble
	MOV	#50 ms,R12
	CALL	#Delay
;now states are:
;(1) 8-bit mode
;(2) 4-bit mode waiting for lower nibble
;(3) 4-bit mode waiting for higher nibble
	MOV.B	#0x30,R12
;(1)"set 8-bit mode" command	->	DL=8,LINES=1,FONT=5*7
;(2)lower nibble of (*) command ->	LINES=1,FONT=5*7
;(3)"set 8-bit mode" command higher nibble (**)	->	DL=8
	CALL	#OutNibble
	MOV	#200 mks,R12
	CALL	#Delay
;now states are:
;(1) 8-bit mode
;(2) 8-bit mode
;(3) 4-bit mode waiting for lower nibble
	MOV.B	#0x30,R12
;(1)"set 8-bit mode" command	->	DL=8,LINES=1,FONT=5*7
;(2)"set 8-bit mode" command	->	DL=8,LINES=1,FONT=5*7
;(3)lower nibble of (**) command ->	LINES=1,FONT=5*7
	CALL	#OutNibble
	MOV	#200 mks,R12
	CALL	#Delay
;now states are:
;(1) 8-bit mode
;(2) 8-bit mode
;(3) 8-bit mode
	MOV.B	#0x20,R12	; DL=4,LINES=1,FONT=5*7
	CALL	#OutNibble	; one nible because in 8-bit mode
	MOV	#40 mks,R12
	CALL	#Delay
;display in 4-bit mode now and requires 2 nibbles per command
	MOV.B	#0x28,R12	; DL=4,LINES=2,FONT=5*7
	CALL	#WriteLCDCommand
	MOV.B	#0x0C,R12	; Display On, Cursor Off
	CALL	#WriteLCDCommand
ClearScreen:
	MOV.B	#0x01,R12	;Clear Display, return cursor
	CALL	#WriteLCDCommand
	MOV	#1600-40 mks,R12
	CALL	#Delay
	RET
OutNibble:			; bits <7-4> of R12
	AND.B	#0xF0,R12	; mask low tetrade
	AND.B	#0x0F,&LCDPort	; clear D<7-4>
	BIS.B	R12,&LCDPort	; write 4 bits to LCD
	BIS.B	#_E,&LCDPort
	BIC.B	#_E,&LCDPort
	RET
WriteLCDCommand:		; command code in R12
	BIC.B	#_RS,&LCDPort	; data is a Command
WriteChar:			; char code in R12
; _RS remains high after previous write if WriteChar
	PUSH	R13
	MOV.B	R12,R13		; save lo tetr
	call	#OutNibble	; high nibble
	RLC.B	R13
	RLC.B	R13
	RLC.B	R13
	RLC.B	R13
	MOV.B	R13,R12
	CALL	#OutNibble	; low nibble
	BIS.B	#_RS,&LCDPort	; next data is a character
	MOV	#40 mks,R12
	POP	R13
Delay:				; Time in R12
	NOP			; 1 cycle
	ADD	#-1,R12		; 1 cycle
	JNE	Delay		; 2 cycles
	RET
WriteString:			; pointer to string in R12
	PUSH	R13
	MOV	R12,R13
WriteStrLoop:
	MOV.B	@R13+,R12
	TST.B	R12
	JEQ	WriteStrDone
	CALL	#WriteChar
	JMP     WriteStrLoop
WriteStrDone:
	POP	R13
	RET
	END