[SOLVED] code for AT89S52 timer1 to generate delay rolls faster than expected

[papunblg]

I need to generate 1 sec delay. I use the following code. AT89S52 with 12MHZ XTAL. Number of counts C3F4(49,999) + 1.
But P2.1 going high in less than 1 sec.

ORG 0000H

STT: MOV R0,#20
MOV TMOD,#10H
AGAIN: MOV TL1,#4FH
MOV TH1,#0C3H
SETB TR1
BACK: JNB TF1,BACK
CLR TF1
CLR TR1
DJNZ R0,AGAIN
CPL P2.1
SJMP STT
END

 

[qwertyuiop415263]

write this code it will generate the delay of 1.06 sec

ORG 0000H

STT: MOV R0,#15
MOV TMOD,#10H
AGAIN: MOV TL1,#0
MOV TH1,#0
SETB TR1
BACK: JNB TF1,BACK
CLR TF1
CLR TR1
DJNZ R0,AGAIN
CPL P2.1
SJMP STT
END

 

[papunblg]

Thanks for your try. But I need 1 sec delay. Your code is giving 1.9s with 12Mhz xtal.

I myself have solved the problem. My formula to calculate the delay was wrong. Th1 should be 3CH and Tl1 should be B1H
Thanks