i came to know that 8051 get interrupted whenever the timer overflows.. ie TF flag is set
so if i use MODE 1 timer one... the maximum delay after which MCU get interrupted comes out to be 71 ms approx(65535*1.085 micro sec)

so what if i need an interrupt delay more than 71 ms say i want an interrupt after 1sec? how it will possible?

 

You make a loop. Reload the timer, reset the flag. Do it as many times as you need.

 

i came to know that 8051 get interrupted whenever the timer overflows.. ie TF flag is set
so if i use MODE 1 timer one... the maximum delay after which MCU get interrupted comes out to be 71 ms approx(65535*1.085 micro sec)

so what if i need an interrupt delay more than 71 ms say i want an interrupt after 1sec? how it will possible?

Loop
Inside of a loop
Inside of a loop
And so on...
And so on...
And so on...

End
End
End
End
End
End

 

Loop
Inside of a loop
Inside of a loop
And so on...
And so on...
And so on...

End
End
End
End
End
End

I used for loop when we did it in class.

 

A for loop is not the structure I would choose for using an interrupt. The idea is to count interrupts in the interrupt routine. This counter could be any number of bytes long, for a mind bendingly long delay. When the counter expires by reaching 0 or some prescribed value you set a flag(bit) in the interrupt routine. This bit is monitored by the non-interrupt code inside the "do forever" loop. Of course you also need a procedure for initializing the timer, the interrupt counter, and the done flag.