Author : Craig Steiner

Source : 8052.com

What Events Can Trigger Interrupts, and where do they go?

We can configure the 8051 so that any of the following events will cause an interrupt:

• Timer 0 Overflow.
• Timer 1 Overflow.
• Reception/Transmission of Serial Character.
• External Event 0.
• External Event 1.

In other words, we can configure the 8051 so that when Timer 0 Overflows or when a character is sent/received, the appropriate interrupt handler routines are called.

Obviously we need to be able to distinguish between various interrupts and executing different code depending on what interrupt was triggered. This is accomplished by jumping to a fixed address when a given interrupt occurs.

By consulting the above chart we see that whenever Timer 0 overflows (i.e., the TF0 bit is set), the main program will be temporarily suspended and control will jump to 000BH. It is assumed that we have code at address 000BH that handles the situation of Timer 0 overflowing.