[求助]汇编指令解释
; Compiled with: PIC Simulator IDE v6.80; Microcontroller model: PIC16F877
; Clock frequency: 4.0 MHz
;
; The address of 'ad_action' (bit) (global) is 0x1F,2
; The address of 'display' (byte) (global) is 0x6
display EQU 0x6
; Begin
R0L EQU 0x20
R0H EQU 0x21
R1L EQU 0x22
R1H EQU 0x23
R2L EQU 0x24
R2H EQU 0x25
R3L EQU 0x26
R3H EQU 0x27
R4L EQU 0x28
R4H EQU 0x29
R5L EQU 0x2A
R5H EQU 0x2B
ORG 0x0000
BCF PCLATH,3
BCF PCLATH,4
GOTO L0003
ORG 0x0004
RETFIE
L0003:
; 1: Symbol ad_action = ADCON0.GO_DONE 'set new name for A/D conversion start bit
; 2: Symbol display = PORTB 'set new name for PORTB used to display the conversion result
; 3:
; 4: TRISB = %00000000 'set PORTB pins as outputs
BSF STATUS,RP0
CLRF 0x06
; 5: TRISA = %111111 'set PORTA pins as inputs
MOVLW 0x3F
MOVWF 0x05
; 6: ADCON0 = 0xc0 'set A/D conversion clock to internal source
BCF STATUS,RP0
MOVLW 0xC0
MOVWF 0x1F
; 7: ADCON1 = 0 'set PORTA pins as analog inputs
BSF STATUS,RP0
CLRF 0x1F
; 8: High ADCON0.ADON 'turn on A/D converter module
BCF STATUS,RP0
BSF 0x1F,0
; 9:
; 10: main:
L0001:
; 11: Gosub getadresult 'go to conversion routine
CALL L0002
; 12: display = ADRESH 'display the result of the conversion
MOVF 0x1E,W <----------------------此处W是什么？
MOVWF 0x06
; 13: Goto main 'repeat forever
GOTO L0001
; 14: End
L0004: GOTO L0004
; 15:
; 16: getadresult: 'conversion routine
L0002:
; 17: High ad_action 'start the conversion
BSF 0x1F,2
; 18: While ad_action 'wait until conversion is completed
L0005:
BTFSS 0x1F,2
GOTO L0006
; 19: Wend
GOTO L0005
L0006: MOVLW 0x1F
ANDWF STATUS,F <----------------------此处F是什么？
; 20: Return
RETURN
; End of program
L0007: GOTO L0007
; End of listing
END
刚学PIC，请学长释疑。谢谢 MOVF 0x1E,W ;传送寄存器地址为0x1E中的内容到工作寄存器(累加器)
ANDWF STATUS,F ;工作寄存器(累加器)和STATUS寄存器做逻辑与运算,结果放入STATUS. MOVF f,d
ANDWF f,d
Destination select; d = 0: store result in W,
d = 1: store result in file register f.
Default is d = 1.
-------------------------------------------
MOVLW 0x1F
ANDWF STATUS,F <----------------------此处F=1？ 为什么不写成ANDWF STATUS,1
接着执行
MOVF 0x1E,W ;从上面两个指令看出 W = 0x1F。那就不是"传送寄存器地址为0x1E中的内容到工作寄存器(累加器)" 沉下去了。 请学长们指教一下。谢谢 wangjiati 发表于 2011-8-15 19:21
MOVF 0x1E,W ;传送寄存器地址为0x1E中的内容到工作寄存器(累加器)
ANDWF STATUS,F ;工作寄存器(累加 ...
高手是否知道PIC的MPY指令结果为什么会加倍？ MOVWF PCLATH 请问这个语句什么意思呢？楼主！？
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