Mips-Assembly/main2.asm at main · StavrosLzp/Mips-Assembly · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
.include "m328PBdef.inc"    ;ATmega328P microcontroller definitions

;Init Stack Pointer
    ldi r24, LOW(RAMEND)
    out SPL, r24
    ldi r24, HIGH(RAMEND)
    out SPH, r24

; delay = (1000*F1+14) cycles (abougt DEL_mS in mSeconds)
.equ FOSC_MHZ=16	;MHz
.equ DEL_mS=1000	;mS
.equ F1=FOSC_MHZ*DEL_mS

ldi r24, low(F1)	    ;
ldi r25, high(F1)	    ;Set delay

.def cart = R17
.def temp = R16

;Set PORTD as output
    ser temp
    out DDRD, temp

right:
    ldi cart, 0b10000000    ;Place cart at the left
loopr:
    out PORTD,cart	    ;Show cart on screen
    rcall delay_1s	    ;wait about 1 second
    lsr cart		    ;move cart to the right
    brcc loopr		    ;repeat until cart is out of screen (at C)

    ldi cart, 0b00000001    ;Place it at the right edge
loopl:
    out PORTD, cart	    ;Show it on screen
    rcall delay_1s	    ;Wait 1 sec
    lsl cart		    ;Move it to the left
    brcc loopl		    ;repeat until cart is out of screen (at C)
    jmp right		    ;Repeat from the beginning


;this routine is used to produce a delay 993 cycles
delay_inner:
    ldi	r23, 247	    ; (1 cycle)
loop3:
    dec r23		    ; 1 cycle
    nop			    ; 1 cycle
    brne loop3		    ; 1 or 2 cycles
    nop			    ; 1 cycle
    ret			    ; 4 cycles

;this routine is used to produce a delay of (1000*F1+14) cycles
delay_1s:
    push r24		    ; (2 cycles)
    push r25		    ; (2 cycles) Save r24:r25

loop4:
    rcall delay_inner	    ; (3+993)=996 cycles
    sbiw r24 ,1		    ; 2 cycles
    brne loop4		    ; 1 or 2 cycles

    pop r25		    ; (2 cycles)
    pop	r24		    ; (2 cycles) Restore r24:r25
    ret			    ; 4 cycles