lcm.s

ARM LCM DISPLAY MOdule control

/* define symbols of system */
.equ	PORTA_MUX,	0x09000000
.equ	PORTA_DATA,	0x09001600
.equ	PORTA_DIR,	0x09001604
.equ	PORTB_MUX,	0x09000004
.equ	PORTB_DIR,	0x0900160c
.equ	PORTB_DATA,	0x09001608
.equ	PORT7_MUX,	0x09000020
.equ	PORT7_DIR,	0x09001644
.equ	PORT7_DATA,	0x09001640
.equ	PORT9_MUX,	0x09000028
.equ	PORT9_DIR,	0x09001654
.equ	PORT9_DATA,	0x09001650

/* define symbols of program */
.set	LCM_WR_1,	0x00000010
.set	LCM_WR_0,	0xffffffef
.set	LCM_RS_1,	0x00000020
.set	LCM_RS_0,	0x000000df
.set	LCM_E_1,	0x00000020
.set	LCM_E_0,	0xffffffdf
.set	LCM_FUNC_SET,	0x00000038
.set	LCM_DISP_ON,	0x0000000e
.set	LCM_DISP_OFF,	0x00000008
.set	LCM_DISP_CLR,	0x00000001
.set	LCM_ENTRY_SET,	0x00000006


.text
.global _start

.code 32
_start:
/* setup PORT B */
start:		ldr	r0, =PORTB_DIR
		ldr	r1, =0x00000000
		str	r1, [r0]
		
		ldr	r0, =PORTB_DATA
		ldr	r1, =0x00000000
		str	r1, [r0]
		
		ldr	r0, =PORTB_MUX
		ldr	r1, =0x00000faa
		str	r1, [r0]

/* setup PORT 9 */
		ldr	r0, =PORT9_DIR
		ldr	r1, =0x00000000
		str	r1, [r0]

		ldr	r0, =PORT9_DATA
		ldr	r1, =0x00000000
		str	r1, [r0]

		ldr	r0, =PORT9_MUX
		ldr	r1, =0x00000140
		str	r1, [r0]

/* initialize LCM */		
		adr	r6, lcm_init_para
		mov	r8, #5
		
lcm_init_loop:	ldrb	r1, [r6]
		ldr	r2, =LCM_RS_0
		bl	lcm_write
		add	r6, r6, #1
		subs	r8, r8, #1
		bne	lcm_init_loop		

/* display Hello! */		
		adr	r6, string_hello
		mov	r8, #6
		
display_loop:	ldrb	r1, [r6]
		ldr	r2, =LCM_RS_1
		bl	lcm_write
		add	r6, r6, #1
		subs	r8, r8, #1
		bne	display_loop

/* program wait here */
end_loop:	b	end_loop		

/* lcm write subroutine */
lcm_write:	mov	r7, lr

		mov	r3, #0
		mov	r5, #0

@ set E=0
		ldr	r0, =PORT9_DATA
		ldr	r4, =LCM_E_0
		and	r3, r3, r4
		str	r3, [r0]

		ldr	r0, =0x1fff
		bl	delay

@ set RS and set R/W=0		
		ldr	r0, =PORT7_DATA
		orr	r5, r5, r2
		str	r5, [r0]
		ldr	r0, =PORT9_DATA
		ldr	r4, =LCM_WR_0
		and	r3, r3, r4
		str	r3, [r0]
	
		ldr	r0, =0x1fff
		bl	delay

@ set E=1			
		ldr	r0, =PORT9_DATA
		ldr	r4, =LCM_E_1
		orr	r3, r3, r4
		str	r3, [r0]

		ldr	r0, =0x1fff
		bl	delay

@ set D[7:0]		
		ldr	r0, =PORTB_DATA
		str	r1, [r0]		

		ldr	r0, =0x1fff
		bl	delay

@ set E=0			
		ldr	r0, =PORT9_DATA
		ldr	r4, =LCM_E_0
		and	r3, r3, r4
		str	r3, [r0]

		ldr	r0, =0x1fff
		bl	delay

		mov	lr, r7
		mov	pc, lr
		
/* delay subroutine */
delay:		subs	r0, r0, #1
		bne	delay
		mov	pc, lr

/* declare constant */
lcm_init_para:
.byte		LCM_FUNC_SET, LCM_DISP_OFF, LCM_DISP_CLR, LCM_DISP_ON, LCM_ENTRY_SET
string_hello:
.ascii		"Hello!"

.end