21.7.3 Interrupt Sources

FIQ always drives Interrupt Source 0.

The System Controller interrupt drives Interrupt Source 74.

The System Controller interrupt is the result of the OR-wiring of the System Controller interrupt lines. When a System Controller interrupt occurs, the service routine must first distinguish the cause of the interrupt. This is performed by reading successively the status registers of the System Controller peripherals.

Interrupt sources 2 to 73 and 75 to 127 can either be connected to the interrupt outputs of an embedded user peripheral, or to external interrupt lines. The external interrupt lines can be connected either directly or through the PIO Controller.

PIO controllers are considered as user peripherals in the scope of interrupt handling. Accordingly, the PIO controller interrupt lines are connected to interrupt sources 2 to 73 and 75 to 127.

The peripheral identification defined at the product level corresponds to the interrupt source number (as well as the bit number controlling the clock of the peripheral). Consequently, to simplify the description of the functional operations and the user interface, the interrupt sources are named FIQ, SYS, and PID2 to PID73 and PID75 to PID127.

AIC0 manages all Non-Secure Interrupts including IRQn; AIC1 manages all Secure Interrupts including FIQ.

Each AIC has its own User Interface. The user should pay attention to use the relevant user interface for each source.