prog44b.asm

主要是8051源代码

;  PROG44b - Run through the Tones  
;
;  Simple Application to Run Through Each Tone Twice a Second
;
;  This Application after power up, Sets up Timer 0 to Interrupt at
;   880 Hz and Outputs a 440 Hz Tone, Waits one Second and then Goes
;   to the Next Tone Up, Up to "HighD"
;
;  Myke Predko
;  98.05.30
;
;  Hardware Notes:
;  AT89C2051 is used as the Microcontroller
;   - Oscillator Speed is 1.8432 MHz
;  P1.7 is Connected to a 8 Ohm Speaker Through 0.47 uF Cap

;  Constant Declarations
LA  EQU 81                      ;  A  -  880 Hz
LAS EQU 91                      ;  A# -  932 Hz
LB  EQU 101                     ;  B  -  988 Hz
LC  EQU 109                     ;  C  - 1046 Hz
LCS EQU 117                     ;  C# - 1108 Hz
LD  EQU 125                     ;  D  - 1174 Hz
LDS EQU 133                     ;  D# - 1249 Hz
LE  EQU 139                     ;  E  - 1318 Hz
LF  EQU 146                     ;  F  - 1396 Hz
LFS EQU 152                     ;  F# - 1480 Hz
LG  EQU 158                     ;  G  - 1568 Hz
LGS EQU 164                     ;  G# - 1662 Hz
HA  EQU 169                     ;  A  - 1760 Hz
HAS EQU 174                     ;  A# - 1873 Hz
HB  EQU 178                     ;  B  - 1976 Hz
HC  EQU 183                     ;  C  - 2094 Hz
HCS EQU 187                     ;  C# - 2218 Hz
HD  EQU 191                     ;  D  - 2350 Hz

;  Variable Declarations
Flags EQU 020h                  ;  Bit 0 Is Set for a "Pause"


;  Macros


;  Mainline
 org 0                          ;  Execution Starts Here
  ajmp    Mainline

 org 00Bh                       ;  Timer0 Interrupt
Timer0:

  jb      0,Timer0End           ;  If a Pause, Don't Trigger the Timer

  cpl     P1.7                  ;  Toggle the Timer

Timer0End:

  reti

 org 01Bh
Timer1:                         ;  Interrupt Every 0.02 Seconds

  djnz    R0,Timer1End          ;  If Not Zero, Then Don't Change Note

  mov     R0,#9                 ;  Reset the Note Timer

  inc     R1                    ;  Point to the Next Value

  clr     0                     ;  Can Output the Note
  mov     A,R1                  ;  Can We Get the Note?
  acall   GetNote               ;  Get the Next Note
  mov     TL0,A                 ;   Save the Next Note
  mov     TH0,A

  jc      Timer1End             ;  Did We Go Too Far?

  mov     R1,#0                 ;  Yes, Reset the Timer

  setb    0                     ;  Execute a Pause

Timer1End:                      ;  Timer1 Interrupt Handler Finished

  reti


MainLine:                       ;  Mainline of the Program

  mov     R0,#9                 ;  R0 is the Beat Timer

  mov     R1,#1                 ;  R1 is the Note Counter

  clr     0                     ;  No Pause

  mov     TMOD,#%00000010       ;  Run Timer0 in Mode 2 and Timer1 in Mode 1
  mov     A,#1                  ;  Get the First Note
  acall   GetNote
  mov     TH0,A                 ;  Enable the Timer to Reload at 880 Hz.  
  mov     TL0,A
  orl     TCON,#050h            ;  Enable Timer0 to Run

  mov     IE,#%10001010         ;  Enable Timer0 Interrupt

Loop:
  ajmp    Loop


GetNote:                        ;  Return the Note Value for the Index in "A"

  clr     C                     ;  Do We Have a Valid Note?
  subb    A,#19
  jnc     InitNoteTable         ;  If Carry NOT Set, then "NO" Value to Get

  add     A,#(19+NoteTable-InitNoteTable)  ;  Restore the Table Position with Note
  movc A,@A+PC			;  Get the Table Value
InitNoteTable:			;  Table Offset to Display

  ret

NoteTable:                      ;  Table of Notes
  db      1                     ;  First Value is a "Pause"
  db      LA
  db      LAS
  db      LB
  db      LC
  db      LCS
  db      LD
  db      LDS
  db      LE
  db      LF
  db      LFS
  db      LG
  db      LGS
  db      HA
  db      HAS
  db      HB
  db      HC
  db      HCS
  db      HD