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.