dacs.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

,,,;***************************************************
,,,;       DACS.ASM        MPB     11-2-06
,,,;
,,,;       Test program for parallel
,,,;       and serial D/A Converters
,,,;       DAC0808 & MCP4921
,,,;
,,,;       Proteus simulation DACS.DSN
,,,;
,,,;***************************************************
,,,
,,,        PROCESSOR 16F877A
,,,        INCLUDE "P16F877A.INC"
00002007,3731,,        __CONFIG 0X3731
,,,
,,,Hibyte  EQU     020     ; SPI data high byte
,,,Lobyte  EQU     021     ; SPI data low byte
,,,
,,,        ORG 0           ; Load at default range
00000000,0000,,        NOP             ; for ICD operations
,,,
,,,; Initialise parallel and serial ports -------------
,,,
00000001,1683 1303,,        BANKSEL TRISD
00000003,0188,,        CLRF    TRISD           ; Parallel port
00000004,1287,,        BCF     TRISC,5         ; Serial data
00000005,1187,,        BCF     TRISC,3         ; Serial clock
00000006,1007,,        BCF     TRISC,0         ; Chip select
00000007,0194,,        CLRF    SSPSTAT         ; default SPI mode
,,,
00000008,1283 1303,,        BANKSEL PORTD
0000000A,0188,,        CLRF    PORTD           ; zero PDAC
0000000B,0194,,        CLRF    SSPCON          ; default SPI mode
,,,
0000000C,3039,,        MOVLW   B'00111001'     ; Initial SDAC data
0000000D,00A0,,        MOVWF   Hibyte          ; and store
0000000E,30FF,,        MOVLW   B'11111111'
0000000F,00A1,,        MOVWF   Lobyte
,,,
,,,; Check buttons ------------------------------------
,,,
00000010,1886,up,up      BTFSC   PORTB,1         ; Test UP button
00000011,2816,,        GOTO    down            ; and jump if off
00000012,0A88,,        INCF    PORTD           ; Increment PDAC
00000013,0AA0,,        INCF    Hibyte          ; Increment SDAC
00000014,1C86,waitup,waitup  BTFSS   PORTB,1         ; Wait for..
00000015,2814,,        GOTO    waitup          ; button release
,,,
00000016,1906,down,down    BTFSC   PORTB,2         ; Test DOWN button
00000017,281C,,        GOTO    spi             ; and jump if off
00000018,0388,,        DECF    PORTD           ; Decrement PDAC
00000019,03A0,,        DECF    Hibyte          ; Decrement SDAC
0000001A,1D06,waitdo,waitdo  BTFSS   PORTB,2         ; Wait for..
0000001B,281A,,        GOTO    waitdo          ; button release
,,,
,,,; Send 16-bit data to SDAC via SPI port ------------
,,,
0000001C,1694,spi,spi     BSF     SSPCON,SSPEN    ; Enable SPI port
,,,
0000001D,1007,,        BCF     PORTC,0         ; Enable SDAC chip
0000001E,0820,,        MOVF    Hibyte,W        ; Get high data
0000001F,0093,,        MOVWF   SSPBUF          ; and send it
00000020,1D8C,waithi,waithi  BTFSS   PIR1,SSPIF      ; Wait for..
00000021,2820,,        GOTO    waithi          ; SPI interrupt
00000022,118C,,        BCF     PIR1,SSPIF      ; Reset interrupt
,,,
00000023,0821,,        MOVF    Lobyte,W        ; Get low data
00000024,0093,,        MOVWF   SSPBUF          ; and send it
00000025,1D8C,waitlo,waitlo  BTFSS   PIR1,SSPIF      ; Wait for..
00000026,2825,,        GOTO    waitlo          ; SPI interrupt
00000027,118C,,        BCF     PIR1,SSPIF      ; Reset interrupt
,,,
00000028,1407,,        BSF     PORTC,0         ; Disable SDAC chip
,,,
,,,; Run output loop until reset ---------------------
,,,
00000029,1806,,        BTFSC   PORTB,0         ; Test run button
0000002A,2810,,        GOTO    up              ; and repeat loop
,,,
0000002B,0A88,run,run     INCF    PORTD           ; Increment PDAC
0000002C,282B,,        GOTO    run
,,,
,,,        END ;---------------------------------------