E (Interrupt Enable) Register
E (Interrupt Enable) Register
E (Interrupt Enable) Register
external sources and execute their task. It then passes the control to the main program where it
had left off.
8051 has 5 interrupt signals, i.e. INT0, TFO, INT1, TF1, RI/TI. Each interrupt can be enabled or
disabled by setting bits of the IE register and the whole interrupt system can be disabled by
clearing the EA bit of the same register.
In 8051, five type of interrupt
It disables all interrupts. When EA = 0 no interrupt will be acknowledged and EA = 1
EA IE.7
enables the interrupt individually.
A low priority interrupt can only be interrupted by the high priority interrupt, but not interrupted by
another low priority interrupt.
If two interrupts of different priority levels are received simultaneously, the request of higher priority
level is served.
If the requests of the same priority levels are received simultaneously, then the internal polling
sequence determines which request is to be serviced.
TCON Register
TCON register specifies the type of external interrupt to the microcontroller.