OK, I'm a novice with the 8051. How do you map a port pin to an external interrupt (or visa versa, say External interrupt 2)? I'm assuming that there are no dedicated pins for each of the seven Ex. interrupts on my chip and they have to be assigned somehow to a pin/bit on a specific port. Is this assumption correct? -Michael
In standard 8051 types, these assignements are fixed in hardware. Some variants may be assignable, but I havent seen any yet. The best place to start is with the data sheet from the specific chip manufacturer, since there are so many variants, you really need the data sheet. Normally you would just put the vector to you interrupt code at a predefined address, and just enable the specific interrupt to get a response.