Everyone, let's go back to "simpler times" when if there was insufficient information, we picked the questioner's brain to see if we could help them. Let's not scare people away by being too heavy-handed in our responses. Also, remember that language can be a barrier that causes a light-hearted response to be interpreted as offensive sarcasm.

Ranjit: Having Ext. Int. 0 triggered when the level goes from 1 to 0 is known as being negative-edge-triggered. As was mentioned in a previous post, to configure your program to receive negative-edge-triggered interrupts do the following:

1. Set the EX0 bit (enable External Interrupt 0).
2. Set the IT0 (TCON.0) bit (set edge-triggered mode).
3. Set the EA bit (global interrupt enable).

Subsequently, an external interrupt 0 will be provoked each time the INT0 line goes from 1-0.

Hope this helps,
Craig Steiner