Specifications

• Division error
• Fast translation lookaside buffer (TLB) miss (MMU only)
• Double TLB miss (MMU only)
• TLB permission violation (MMU only)
• MPU region violation (MPU only)
External Interrupt Controller Interface
The EIC interface enables you to speed up interrupt handling in a complex system by adding a custom
interrupt controller.
The EIC interface is an Avalon-ST sink with the following input signals:
• eic_port_valid
• eic_port_data
Signals are rising-edge triggered, and synchronized with the Nios II clock input.
The EIC interface presents the following signals to the Nios II processor through the eic_port_data
signal:
• Requested handler address (RHA)—The 32-bit address of the interrupt handler associated with the
requested interrupt.
• Requested register set (RRS)—The six-bit number of the register set associated with the requested
interrupt.
• Requested interrupt level (RIL)—The six-bit interrupt level. If RIL is 0, no interrupt is requested.
• Requested nonmaskable interrupt (RNMI) flag—A one-bit flag indicating whether the interrupt is to
be treated as nonmaskable.
Table 5-10: eic_port_data Signal
Bit Fields
44 ...
RHA
... 13 12 11 10 9 8 7 6 5 4 3 2 1 0
RHA RRS RNMI RIL
Following Avalon-ST protocol requirements, the EIC interface samples eic_port_data only when
eic_port_valid is asserted (high). When eic_port_valid is not asserted, the processor latches the
previous values of RHA, RRS, RIL and RNMI. To present new values on eic_port_data, the EIC must
transmit a new packet, asserting eic_port_valid. An EIC can transmit a new packet once per clock cycle.
For an example of an EIC implementation, refer to the Vectored Interrupt Controller chapter in the
Embedded Peripherals IP User Guide.
Related Information
Embedded Peripherals IP User Guide
ECC
The Nios II/f core has the option to add ECC support for the following Nios II internal RAM blocks.
NII51015
2015.04.02
External Interrupt Controller Interface
5-13
Nios II Core Implementation Details
Altera Corporation
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