how to calculate delay time in 8051

[mishra12]

pls help me on this topic



delay2:
mov r5,#180
cont5: mov r2,#255
cont4: mov r1,#255
cont3: djnz r1, cont3
djnz r2, cont4
djnz r5, cont5
ret
end
how 180 comes is there any formula to calculate ? pls help soon
thanks

 

[qwertyuiop415263]

in 8051 assembly programming each instruction takes some machines cycle to execute. machine cycle depend on your controller and crystal value.

e.g 8051 with 11.0952MHz crystal ,machine cycle=1.085us

MOV take 1 machine cycle time delay=1*1.085us
DJNZ takes 2 machine cycles time delay=2*1.085us

adding all the instruction's time sepatrately and add.

you can see this book "8051 and embedded system" by Ali Mazidi for more detail

 

[bassa]

Here you can find a method to calculate the delay time



hope your comments

regards
bassa

 

[ctownsend]

Just download the time8051 program here:
**broken link removed**

you just enter your clock speed, and the amount of microseconds, and you have the source code in assembly. It's really easy.

look at my post here:


Good Luck