Subversion Repositories RISCMCU

AVRASM ver. 1.30  COUNTER.ASM Sun Jul 07 15:58:37 2002

         ; This program is for simulation purpose

         ; It demo how the MCU output 3, 2 and 1 to each port (Port B, Port C and Port D)

         ; There are 3 approaches used in accomplishing the above task

          .include "riscmcu.inc"

         ;***** I/O Register Definitions

          .equ  SREG    =$3f

          .equ  GIMSK   =$3b

          .equ  TIMSK   =$39

          .equ  TIFR    =$38

          .equ  MCUCR   =$35

          .equ  TCCR0   =$33

          .equ  TCNT0   =$32

          .equ  PORTB   =$18

          .equ  DDRB    =$17

          .equ  PINB    =$16

          .equ  PORTC   =$15

          .equ  DDRC    =$14

          .equ  PINC    =$13

          .equ  PORTD   =$12

          .equ  DDRD    =$11

          .equ  PIND    =$10

         ;***** Bit Definitions

          .equ  INT0    =6

          .equ  TOIE0   =1

          .equ  TOV0    =1

          .equ  ISC01   =1

          .equ  ISC00   =0

          .equ  CS02    =2

          .equ  CS01    =1

          .equ  CS00    =0

          .def  ZP      =r30

          .def  B = r16

          .def  C = r17

          .def  D = r18

          .def  TEMP = r19

000000 c002             rjmp    reset           ; reset vector

000001 9508             ret                     ; external interrupt vertor(not use)

000002 9508             ret                     ; timer overflow interrupt vertor (not use)

          reset:

000003 2733             clr     TEMP            ; r19 = 00

000004 9530             com     TEMP            ; r19 = FF

000005 bb37             out     DDRB,TEMP       ; set all Port B pins as output

000006 bb34             out     DDRC,TEMP       ; set all Port C pins as output

000007 bb31             out     DDRD,TEMP       ; set all Port D pins as output

         ; Approach 1, output to Port B

000008 e003             ldi     B,3             ; r16 = 03

000009 bb08      again1:        out     PORTB,B         ; Port B now output 03

00000a 950a             dec     B               ; r16 = r16 - 1

00000b 3000             cpi     B,0             ; if r16 = 0,

00000c f7e1             brne    again1          ;   branch to again1

         ; Approach 2, output to Port C

00000d 2733             clr     TEMP            ; r19 = 00

00000e 9513             inc     C               ; r17 = 01

00000f 9513             inc     C               ; r17 = 02

000010 9513             inc     C               ; r17 = 03

000011 bb15      again2:        out     PORTC,C         ; Port C now output 03

000012 5011             subi    C,1             ; r17 = r17 - 1

000013 1313             cpse    C,TEMP          ; if r17 != r19 (means if r17 != 0),

000014 cffc             rjmp    again2          ;    branch to again2

         ; Approach 3, output to Port D

000015 2722             clr     D               ; r18 = 00

000016 5f2d             subi    D,-3            ; r18 = r18 - (-3) = 03

000017 bb22      again3:        out     PORTD,D         ; Port D now output 03

000018 952a             dec     D               ; r18 = r18 -1

000019 b73f             in      TEMP,SREG       ; transfer the value of SR to R19

00001a ff31             sbrs    TEMP,1          ; if bit 1 in R19 (the Z-flag) is set, skip the next instruction

00001b cffb             rjmp    again3          ;    else branch to again3

00001c cfff      end:   rjmp    end             ; Branch Forever

00001d 9478             sei                     ; (Set I-Bit in SR) This 2 instructions won't execute

00001e 9468             set                     ; (Set T-Bit in SR)   even they are fetched to the IR

Assembly complete with no errors.