PIC16F877A timing TMR0

The following experimental program is written to make the 8 LEDs on the RC port light up one by one, and then turn off one by one after all are lit, and repeat this cycle. The timer query method is used to control the delay, and the timer interrupt is not used. The interrupt program will be written above later.

            tmr0     equ    01h
             pcl      equ    02h
             status   equ    03h
             option_reg  equ  81h
             intcon    equ    0bh
             portc equiv 07h
             trisc     equ    87h
             tmr0data  equ     15h
             count     equ    20h
             rp0       equ    5h
             org      0000h
             nop
             goto     main
             org      0005h
       main  
             nop
             bsf      status,rp0
             movlw 00h
             movwf    trisc
             movlw 07h
             movwf    option_reg
             bcf      status,rp0
             clrf     count
      walk1
             movf     count,0
             call     read
             movwf portc
             incf     count,1
             movlw 0fh
             andwf    count,1
             call     delay
             call     delay
             call     delay
             call     delay
             call     delay
             call     delay
             call     delay
             goto      loop1
       delay
             bcf      intcon,2
             movlw tmr0data
             movwf    tmr0
       delay1
             btfss    intcon,2
             goto      delay1
             return
       
      read   
             addwf     pcl,1
            retlw      b'10000000'
            retlw      b'11000000'  
            retlw      b'11100000'
            retlw      b'11110000'
            retlw      b'11111000'
            retlw      b'11111100'
            retlw      b'11111110'
            retlw      b'11111111'
            retlw      b'11111110'
            retlw      b'11111100'
            retlw      b'11111000'
            retlw      b'11110000'
            retlw      b'11100000'
            retlw      b'11000000'
            retlw      b'10000000'
            retlw      b'00000000'
            end

This program uses TMR0 of 16F877A. For specific settings, please look up the function descriptions of INTCON, OPTION_REG, TMR0 and other related special working registers in 16F877C. I recommend the PIC microcontroller practical tutorial written by Mr. Li Xuehai.