pic16f877

Mar 13, 2005 1 Replies

hey there, i really need some help in the general area of PIC 16f877. i am using the PICDEM 2 plus board that comes with the mplab icd 2 in circuit debugger. the code below is a simple code but i am unfamiliar with the coding as i have just started assembly.



what does it all mean?



list p=16F877 #include __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_OFF & _HS_OSC & _WRT_ENABLE_ON & _LVP_OFF & _DEBUG_OFF & _CPD_OFF



; '__CONFIG' directive is used to embed configuration data within .asm file.



;***** VARIABLE DEFINITIONS



ctr0 equ 0x20 ctr1 equ 0x21 ctr2 equ 0x22 ctr3 equ 0x23 work equ 0x24



;**********************************************************************


org 0x000 ; processor reset vector clrf PCLATH ; ensure page bits are cleared goto main ; go to beginning of program



main ;beginning of the program banksel TRISB ;select the bank containing TRISB movlw 0xf3 ;port B is the o/p movwf TRISB ; banksel PORTB ;select the bank containing TRISB



movlw 0x08 movwf work movlw 0xf0 movwf PORTB movlw 0xf4 movwf PORTB



mainlo movlw 0xff movwf ctr2 loop1 movlw 0xff movwf ctr0



loop decf ctr0,1 bnz loop decf ctr2,1 bnz loop1



movf work,0 movwf PORTB comf work,1 ; toggle led's



movf work,0 movwf PORTB comf work,1



goto mainlo



END ; directive 'end of program'



because i am just trying to display the nightrider effect with the LEDs but its a little more difficult than i thought. any help would be much apprieciated,



Regards,



Colm


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