Timer

I need help with my project. Need to do timer from 0 to 999 / (0,1,2 .... 999 every second) and display it in 3 digit 7 segment LED display Here I have a timer from 0 to 9 every second. I need help because I do not know how to proceed ďalej.PIC 16F887.Program is in mikrobasic.
I know I have to use multiplexing. displays are the common cathode.

loop:

PORTA.0 = 1 / on port RA0 - RA2 outputs are the base of the transistor
PORTD = $ 3F / number 0 on the display
delay_ms (900)
PORTD = $ 06
delay_ms (900)
PORTD = $ 5B
delay_ms (900)
PORTD = $ 4F
delay_ms (900)
PORTD = $ 66
delay_ms (900)
PORTD = $ 6D
delay_ms (900)
PORTD = $ 7D
delay_ms (900)
PORTD = $ 07
delay_ms (900)
PORTD = $ 7F
delay_ms (900)
PORTD = $ 6F
delay_ms (900)

goto loop

I have just done something similar but used a MAX7219, as the processor had other things to do.

The delays you are using will probably lead to the seven segment display flashing.

What might help is a loop that just outputs to port D with a variable such as SECONDS.

loop
PORTD = SECONDS;
delay_ms(50); //maybe even faster
goto loop

and just have a timer interupt which fires every second and increases SECONDS by 1

Sorry I dont use basic but hopefully you get the idea.

Set up timer0 as an 8 bit, 64:1 pre-scale, interrupts on. and write to each individually. The numbers shouldn't flash but stay constant..

Have an array for the figures 0 = 0x3f..etc..

Then in the interrupt write figure A.. next interrupt.. figure B.. so on... adjust the count in the main loop.