A51 MACRO ASSEMBLER  TIMER                                                                07/28/2006 13:21:21 PAGE     1


MACRO ASSEMBLER A51 V8.00
OBJECT MODULE PLACED IN Timer.OBJ
ASSEMBLER INVOKED BY: e:\Program Files\Keil\C51\BIN\A51.EXE Timer.asm SET(SMALL) DEBUG EP

LOC  OBJ            LINE     SOURCE

0000                   1                     ORG             00H
  2710                 2     TICK    EQU             10000                           ;10000×100us=1s
  009C                 3     T100us  EQU             256-100                         ;100us時間常數（12M）
  0030                 4     C100us  EQU             30H                                     ;100us計數單元
  0040                 5     LEDBUF  EQU             40H                             
  0090                 6     LED             BIT             P1.0
0000 020026            7     LJMP    START                                           ;跳至主程序
000B                   8                     ORG             000BH                           ;中斷子程序起始地址
000B C0D0              9     T0INT:  PUSH    PSW                                     ;狀態保護
000D E531             10                     MOV             A,C100us+1
000F 7002             11                     JNZ             GOON
0011 1530             12                     DEC             C100us                          ;秒計數值減1
0013 1531             13     GOON:   DEC             C100us+1
0015 E530             14                     MOV             A,C100us
0017 4531             15                     ORL             A,C100us+1
0019 7008             16                     JNZ             EXIT                            ;100us計數器不為0，返回
001B 753027           17                     MOV             C100us,#HIGH(TICK)      ;100us計數器為0，重置計數器
001E 753110           18                     MOV             C100us+1,#LOW(TICK)
0021 B240             19                     CPL             LEDBUF                          ;取反LED
0023 D0D0             20     EXIT:   POP             PSW
0025 32               21                     RETI
                      22             
0026 758902           23     START:  MOV             TMOD,#02H                       ;方式2，定時器
0029 758C9C           24                     MOV             TH0,#T100us                     ;置定時器初值
002C 758A9C           25                     MOV             TL0,#T100us
002F 75A882           26                     MOV             IE,#10000010B           ;EA=1，IT0=1
0032 D28C             27                     SETB    TR0                                     ;開始定時
0034 C240             28                     CLR             LEDBUF
0036 C290             29                     CLR             LED
0038 753027           30                     MOV             C100us,#HIGH(TICK)      ;設置10000次計數值
003B 753110           31                     MOV             C100us+1,#LOW(TICK)
003E A240             32     LOOP:   MOV             C,LEDBUF
0040 9290             33                     MOV             LED,C
0042 02003E           34                     LJMP    LOOP
                      35                     END
A51 MACRO ASSEMBLER  TIMER                                                                07/28/2006 13:21:21 PAGE     2

SYMBOL TABLE LISTING
------ ----- -------


N A M E             T Y P E  V A L U E   ATTRIBUTES

C100US . . . . . .  N NUMB   0030H   A   
EXIT . . . . . . .  C ADDR   0023H   A   
GOON . . . . . . .  C ADDR   0013H   A   
IE . . . . . . . .  D ADDR   00A8H   A   
LED. . . . . . . .  B ADDR   0090H.0 A   
LEDBUF . . . . . .  N NUMB   0040H   A   
LOOP . . . . . . .  C ADDR   003EH   A   
P1 . . . . . . . .  D ADDR   0090H   A   
PSW. . . . . . . .  D ADDR   00D0H   A   
START. . . . . . .  C ADDR   0026H   A   
T0INT. . . . . . .  C ADDR   000BH   A   
T100US . . . . . .  N NUMB   009CH   A   
TH0. . . . . . . .  D ADDR   008CH   A   
TICK . . . . . . .  N NUMB   2710H   A   
TL0. . . . . . . .  D ADDR   008AH   A   
TMOD . . . . . . .  D ADDR   0089H   A   
TR0. . . . . . . .  B ADDR   0088H.4 A   


REGISTER BANK(S) USED: 0 

ASSEMBLY COMPLETE.  0 WARNING(S), 0 ERROR(S)