[51] Generating 1 second delay using timers in 8051

[phrbob93]

i am Generating 1 second delay using timers in 8051
my concept is like this
iam using 11.0592 crystal frequency

time required for 1 machine cycle is1.085 micro second

if timer is set to 0000h then time required for timer to run once is 65536*1.085= 7.11 ms

now if 7.11*142(times the loop runs) = 1000ms=1sec

so here is my code

---

Code C - [expand]
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#include<reg51.h>
void delay(void);
void main()
{
  while(1)
  {
    P2=0x00;                // led off
 
    delay();                // delay for 1sec
    P2=0xFF;                // led on
 
    delay();                // delay for  1 sec
  }
}
 
 
 void delay(void)
 {
  int i;
  TMOD=0x01;          // timer 0 in mode 1
           
for(i=0;i<14;i++)
  {
     TL0=0x00; // starting value from 0 
     TH0=0x00;
     TR0=1;              // sart timer
     while(TF0==0);       // polling TF flag for high
     TR0=0;               // stop timer
     TF0=0;                // clear flag TF0
 
    }
 }

---

im not getting delay of 1 second, instead i am geting delay of mili seconds.. plz help me where iam wrong

 

[Genovator]

First, its not 7.11ms. Its 71.1ms. So number of loops will be 14. 11.0592MHz crystals are good for baud rates, not timings.
Second, you didn't specified your question.

 

[phrbob93]

First, its not 7.11ms. Its 71.1ms. So number of loops will be 14. 11.0592MHz crystals are good for baud rates, not timings.
Second, you didn't specified your question.

m not getting delay of 1 second, instead i am geting delay of mili seconds.. plz help me where iam wrong

 

[Genovator]

Can't say about the C language, but in ASM, it can be written like this. I guess your C compiler will support assembly with 'ASM' initial in every line.

MOV R1, 0EH

LOOP:
MOV P2, #00H

CALL DELAY
MOV P2, #0FFH

CALL DELAY
JMP LOOP

DELAY:
MOV TMOD, #01H
MOV TH0, #00H
MOV TL0, #00H
SETB TR0
JNB TF0, $
CLR TF0
DJNZ R1, DELAY
RET

 

[Disha Karnataki]

first of all see your target settings that you have correctly entered the crystal frequency as:11.0592mhz