pulse.sdi

代码保护功能处于持续发展中。Microchip 承诺将不断改进产品的代码保护功能。任何试图破坏Microchip 代码保护功能的行为均可视 为违反了《数字器件千年版权法案（Digital Mille

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,,,;
,,,;       PULSE.ASM       MPB             21-8-05
,,,;       Generates timed output interval using Timer 2
,,,;       in compare mode
,,,;       Timer interrupt sets output, cleared after 1ms
,,,;
,,,;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
,,,
,,,        PROCESSOR 16F877A
,,,;       Clock = XT 4MHz, standard fuse settings
00002007,3731,,        __CONFIG 0x3731
,,,
,,,;       LABEL EQUATES   ......................................
,,,
,,,        INCLUDE "P16F877A.INC"  ; Standard register labels
,,,
,,,Count   EQU     20              ; soft timer
,,,
,,,; Program begins ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
,,,
,,,        ORG     0               ; Place machine code
00000000,0000,,        NOP                     ; for ICD mode
00000001,2805,,        GOTO    init            ; Jump over ISR vector
,,,
,,,        ORG     4               ; ISR vector address
00000004,2820,,        GOTO    isr             ; run ISR
,,,
00000005,0000,init,init    NOP
00000006,1683 1303,,        BANKSEL TRISC           ; Select bank 1
00000008,30FB,,        MOVLW   B'11111011'     ; RC2 = output
00000009,0087,,        MOVWF   TRISC           ; Initialise display port
0000000A,3004,,        MOVLW   B'00000100'     ; Timer1 interrupt..
0000000B,008C,,        MOVWF   PIE1            ; ..enable
,,,
0000000C,1283 1303,,        BANKSEL PORTC           ; Select bank 0
0000000E,0187,,        CLRF    PORTC           ; Clear output
0000000F,30C0,,        MOVLW   B'11000000'     ; Peripheral interupt..
00000010,008B,,        MOVWF   INTCON          ; ..enable
00000011,3008,,        MOVLW   B'00001000'     ; Compare mode..
00000012,0097,,        MOVWF   CCP1CON         ; ..set output on match
00000013,3027,,        MOVLW   027             ; Initial value..
00000014,0096,,        MOVWF   CCPR1H          ; .. for high byte (10ms)
00000015,3010,,        MOVLW   010             ; Initial value..
00000016,0095,,        MOVWF   CCPR1L          ; .. for low byte (10ms)
00000017,3001,,        MOVLW   B'00000001'     ; Timer1 enable..
00000018,0090,,        MOVWF   T1CON           ; with internal clock (1MHz)
,,,
00000019,2831,,        GOTO    start           ; Jump to main program
,,,
,,,;       SUBROUTINES............................................
,,,
,,,;       1ms delay with 1us cycle time (1000 cycles)
,,,
0000001A,30F9,onems,onems   MOVLW   D'249'          ; Count for 1ms delay
0000001B,00A0,,        MOVWF   Count           ; Load count
0000001C,0000,loop,loop    NOP                     ; Pad for 4 cycle loop
0000001D,0BA0,,        DECFSZ  Count           ; Count
0000001E,281C,,        GOTO    loop            ; until Z
0000001F,0008,,        RETURN                  ; and finish
,,,
,,,
,,,;       INTERRUPT SERVICE ROUTINE..............................
,,,
,,,;       Reset interrupt, check buttons, generate 1ms pulse
,,,
00000020,018C,isr,isr     CLRF    PIR1            ; clear interrupt flags
00000021,018F,,        CLRF    TMR1H           ; clear timer high..
00000022,018E,,        CLRF    TMR1L           ; ..and low byte
,,,
00000023,1808,,        BTFSC   PORTD,0         ; dec frequency button?
00000024,2828,,        GOTO    other           ; no
00000025,0F96,,        INCFSZ  CCPR1H          ; yes, inc period, zero?
00000026,2828,,        GOTO    other           ; no
00000027,0396,,        DECF    CCPR1H          ; yes, step back
,,,
00000028,1888,other,other   BTFSC   PORTD,1         ; inc frequency button?
00000029,282D,,        GOTO    wait            ; no
0000002A,0B96,,        DECFSZ  CCPR1H          ; yes, inc period, zero?
0000002B,282D,,        GOTO    wait            ; no
0000002C,0A96,,        INCF    CCPR1H          ; yes, step back
,,,
0000002D,201A,wait,wait    CALL    onems           ; wait 1ms
0000002E,1197,,        BCF     CCP1CON,3       ; clear output
0000002F,1597,,        BSF     CCP1CON,3       ; re-enable timer mode
,,,
00000030,0009,,        RETFIE                  ; return to main program
,,,
,,,
,,,;-----------------------------------------------------------
,,,;       Main program
,,,;-----------------------------------------------------------
00000031,2831,start,start   GOTO    start           ; wait for timer interrupt
,,,        END                     ; of source code