initial logic for interrupt

Hello greats,

I use external interrupt in my project.initially if the interrupt signal is low (from spdt switch sw5) when switching on the controller,controller runs very slowly in proteus simulation and real time also.can anybody tell the reason for that? this is my circuit.

The interrupt could be triggering from noise on the line, or oscilate briefly during startup, one of the first things the init code for a program that uses interrupts should do is to immediately disable interrupts until the chip has been initialized.

Do you really need an interrupt?

I usually avoid them by the use of polling.

First off...you don't need SPDT switches on I/O pins. The ports on the 8051 have internal weak pull ups (except Port 0, which is open drain) so no external pull up is needed.

Second off...without seeing your code we cannot even begin to help you with your issue.

If you can post the code for this circuit we can proceed further in assisting you with your design.