My question is :-

1) If it is required that the controller should start its execution when it gets a High from an external Device then how to use the controller pin as input...

2) the condition is that the software should start to execute when an external device sents a low to High Signal. As initially the port pins are in High State.



External Device = logic 0..at this stage controller should not do any thing..

logical =1 ... at this stage controller should do some thing and the state of external device cannot be changed

now suppose that this device is attached at p2.0

how should i write the instruction