【发布时间】：2021-01-04 10:40:45
【问题描述】：
在使用 PIC16F1829 间接寻址时，如何正确清空 RAM 并初始化 FSR0 寄存器？
代码有效。我的问题是，在调试时，尽管 FSR0 寄存器保存 0x70 地址，但其值应存储在地址 0x70 和 0x71 的变量（即本例中的 Delay1 和 Delay2）分别存储在 0x120 和 0x121。
我不知道我错过了什么，因为使用 16 位 FSR 寄存器的例子并不多。因此，任何人都可以提供任何帮助，我们将不胜感激。
LIST p=16f1829 ;list directive to define processor
#INCLUDE <p16f1829.inc> ;processor specific variable definitions
__CONFIG _CONFIG1, (_FOSC_INTOSC & _WDTE_OFF & _PWRTE_OFF & _MCLRE_OFF & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_OFF & _FCMEN_OFF);
__CONFIG _CONFIG2, (_WRT_OFF & _PLLEN_OFF & _STVREN_OFF & _LVP_OFF);
;---------------------------------------------- --------------------------
; UDATA declares a section of uninitialised data
VARIABLES UDATA ; VARIABLES is the name of the section of memory
Delay1 RES 1 ; uninitialised data, placed by linker in GPR's.
Delay2 RES 1 ; uninitialised data, placed by linker in GPR's.
;-------------------------------------------------------------------------
; RESET VECTOR
;-------------------------------------------------------------------------
RESET_VECTOR CODE 0x0000
GOTO START
;-------------------------------------------------------------------------
; INTERRUPT SERVICE ROUTINE
;-------------------------------------------------------------------------
INT_VECTOR CODE 0x0004 ; Interrupt vector location
GOTO START
;-------------------------------------------------------------------------
; MAIN PROGRAM
;-------------------------------------------------------------------------
MAIN_PROG CODE
START
;-------------------------------------------------------------------------
; SET OSCILLATOR TO FACTORY FREQUENCY AND CLEAR GPR's
;-------------------------------------------------------------------------
ERRORLEVEL -302 ; Disable warning accessing register not in bank 0
BANKSEL OSCTUNE ; Configure OPTION_REG and TMR0
MOVLW 0x00 ; Set oscillator to factory calibrated frequency
MOVWF OSCTUNE ;
BANKSEL STATUS
ERRORLEVEL +302 ; Enable warning accessing register not in bank 0
CLEAR_RAM ; code sequence initialises all GPR's to 0x00
MOVLW 0x70 ; initialise pointer to RAM
MOVWF FSR0L
CLRF FSR0H
NEXT
CLRF INDF0 ; clear INDF0 register
INCF FSR0L, F ; inc pointer
BTFSS FSR0L, 7 ; all done?
GOTO NEXT ; no clear NEXT
CONTINUE ; yes CONTINUE
NOP
;-------------------------------------------------------------------------
; REMAINDER OF PROGRAM
;-------------------------------------------------------------------------
; Setup main init
BANKSEL OSCCON ; Selects memory bank containing OSCCON register
MOVLW b'00111000' ; Set CPU clock speed of 500KHz -> correlates to (1/(500K/4)) for each instruction
MOVWF OSCCON ; OSCCON <- 0x38
; Configure the LEDs
BCF TRISC,0 ; Make I/O Pin C0 an output for DS1
BANKSEL LATC ; Selects memory bank containing LATC
CLRF LATC ; Start by turning off all of the LEDs
MAINLOOP:
BSF LATC, 0 ; Turn LED on
ONDELAYLOOP:
DECFSZ Delay1,f ; Waste time.
BRA ONDELAYLOOP ; The Inner loop takes 3 instructions per loop * 256 loops = 768 instructions
DECFSZ Delay2,f ; The outer loop takes an additional 3 instructions per lap * 256 loops
BRA ONDELAYLOOP ; (768+3) * 256 = 197376 instructions / 125K instructions per second = 1.579 sec.
BCF LATC,0 ; Turn off LED C0 - NOTE: do not need to switch banks with 'banksel' since bank2 is still selected
OFFDELAYLOOP:
DECFSZ Delay1,f ; same delay as above
BRA OFFDELAYLOOP
DECFSZ Delay2,f
BRA OFFDELAYLOOP
BRA MAINLOOP ; Do it again...
;-------------------------------------------------------------------------
; END OF PROGRAM
;-------------------------------------------------------------------------
END ; End of program
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标签： debugging assembly microcontroller pic microchip