Dimming a LED using 8051.

[ikelectro]

I want to make a LED glow slowly. But haven't succeed yet. I learn only these command still now over one and half month : mov, add, clr, setb, djnz, lcall, cjne, rr, rl, swap, jnb, jb, ret, nop, jmp, sjmp, jz, jnz. So, is it possible to make a led dimmer with with these instruction?

 

[Ian Rogers]

I think that is most of them...

The two you need are SETB and CLR.... these turn off / on an LED connected ( via a transistor ) to a micro pin..

you then place the code in a forever loop with a variable delay between these two commands

var1   equ   250     ; on time
var2   equ   50     ; off time

loop:
   mov   R0, #var1
   setb   P0.0
on:
   djnz   R0, on     ; wait here for on time
   mov   R0, #var2
   clr    P0.0
off:
   djnz   R0, off    ; wait here for off time
   jmp   loop

end

Something like this... To make the LED come on slowly... Increase var2 while decreasing var1..

 

[dengxinjun]

Why not use the C language to write? So convenient point