By: Masud-ul-Hasan
4
Interrupt System
•- Five interrupt sources in order of polling (priority) sequence are:
• External Interrupt 0
• Timer 0
• External Interrupt 1
• Timer 1
• Serial Port
-The polling sequence is fixed but each interrupt type can be programmed to one of two priority levels.
-If two interrupts of same priority occur simultaneously then polling sequence will determine which is serviced first.
•-   External interrupts can be programmed for edge or level sensitivity.
--   Each interrupt type has a separate vector address.
--   All interrupts are disabled after a system reset and enabled individually by software.