upcase: rmb 3
wchek: rmb 3
dchek: rmb 3
init_sci: rmb 3
input: rmb 3
output: rmb 3
outlhlf: rmb 3
outrhlf: rmb 3
outa: rmb 3
out1byt: rmb 3
out1bsp: rmb 3
out2bsp: rmb 3
outcrlf: rmb 3
outstrg: rmb 3
outstrg0: rmb 3
inchar: rmb 3
*
STACK: equ $8FFF

ONE_MS equ 167 ; for 8 MHz 1000us/6us=167
FIVE_MS equ 835
TEN_MS equ 1670

PORTF equ $2201
DDRF equ $2203
d40us: equ 15 ; 15x6us= 90 us, 60us ok
REG_SEL: equ DB0 ; 0=reg, 1=data
ENABLE: equ DB1
NOT_REG_SEL: equ $FE
NOT_ENABLE: equ $FD
org 0
temp1: rmb 1
pfimg: rmb 1
reset_seq: rmb 1
disp_ram: rmb 3
*
LCDimg: equ pfimg
LCD_RSimg: equ pfimg
LCD_ENimg: equ pfimg

LCD: equ PORTF
LCD_RS: equ PORTF
LCD_EN: equ PORTF
*
org $D000
jmp start

lcd_ini:
ldaa #$FF
staa DDRF
clra
staa pfimg
staa PORTF
ldx #inidsp1 ; point to init. codes.
ldaa #1
staa reset_seq ; need more delay for first reset seq.
jsr outins1 ; output codes.
ldx #inidsp2 ; point to init. codes.
clr reset_seq
jsr outins2 ; output codes.
rts
inidsp1:
fcb 2 ; number of instrutions
fcb $33 ; reset char
fcb $32 ; reste char
inidsp2:
fcb 4 ; number of instrutions
fcb $28 ; 4bit, 2 line, 5X7 dot
fcb $06 ; cursor increment, disable display shift
fcb $0c ; display on, cursor off, no blinking
fcb $01 ; clear display memory, set cursor to home pos
outins1:
pshb ; output instruction command.
jsr sel_inst
ldab 0,x
inx
onext1: ldaa 0,x
jsr wrt_pulse ; initiate write pulse.
inx
jsr d5ms
decb
bne onext1
pulb
rts
*
outins2:
pshb ; output instruction command.
jsr sel_inst
ldab 0,x
inx
onext2: ldaa 0,x
jsr wrt_pulse ; initiate write pulse.
inx
decb
bne onext2
jsr d5ms
pulb
rts
*
delay_10ms:
nop
d10ms: pshx
ldx #TEN_MS
bsr del1
pulx
rts
d5ms: pshx
ldx #FIVE_MS
bsr del1
pulx
rts
del1: dex
inx
dex
bne del1
rts
*
*
sel_data:
psha
* bset LCD_RSimg REG_SEL ; select instruction
ldaa LCD_RSimg
oraa #REG_SEL
bra sel_i
sel_inst:
psha
* bclr LCD_RSimg REG_SEL ; select instruction
ldaa LCD_RSimg
anda #NOT_REG_SEL
sel_i: staa LCD_RSimg
staa LCD_RS
pula
rts
*

lcd_line1:
jsr sel_inst ; select instruction
ldaa #$80 ; starting address for the line1
bra line3
lcd_line2:
jsr sel_inst
ldaa #$C0 ; starting address for the line2
line3: jsr wrt_pulse
*
jsr sel_data
jsr msg_out
rts

* at entry, x must point to the begining of the message,
* b = number of the character to be sent out
*
msg_out:
ldaa 0,x
jsr wrt_pulse
inx
decb
bne msg_out
rts

*
* @ enter, a=data to output
*
wrt_pulse:
pshx
psha ; save it tomporarily.
anda #$f0 ; mask out 4 low bits.
staa temp1 ; save nibble value.
ldaa LCDimg ; get LCD port image.
anda #$0f ; need low 4 bits.
oraa temp1 ; add in low 4 bits.
staa LCDimg ; save it
staa LCD ; output data
*
bsr enable_pulse
ldaa reset_seq
beq wrtpls
jsr d5ms ; delay for reset sequence
*
wrtpls: pula
asla ; move low bits over.
asla
asla
asla
staa temp1 ; store temporarily.
*
ldaa LCDimg ; get LCD port image.
anda #$0f ; need low 4 bits.
oraa temp1 ; add in loiw 4 bits.
staa LCDimg ; save it
staa LCD ; output data
*
bsr enable_pulse
pulx
rts
*
enable_pulse:
* bset LCD_ENimg ENABLE ; ENABLE=high
ldaa LCD_ENimg
oraa #ENABLE
staa LCD_ENimg
staa LCD_EN
* bclr LCD_ENimg ENABLE ; ENABLE=low
ldaa LCD_ENimg
anda #NOT_ENABLE
staa LCD_ENimg
staa LCD_EN
pshx
ldx #d40us
jsr del1
pulx
rts
*
start:
lds #STACK
jsr delay_10ms ; delay 20ms during power up
jsr delay_10ms

jsr lcd_ini ; initialize the LCD

back: ldx #MSG1 ; MSG1 for line1, x points to MSG1
ldab #16 ; send out 16 characters
jsr lcd_line1
*
ldx #MSG2 ; MSG2 for line2, x points to MSG2
ldab #16 ; send out 16 characters
jsr lcd_line2
jsr delay_10ms
jsr delay_10ms
jmp back

MSG1: FCC " ECE3620 WSU "
MSG2: FCC " Prof. M Hassoun "

end