You copied the Doc URL to your clipboard.

10.2. External interface

This is an AHB-Lite bus interface. See External AHB-Lite interface for descriptions of the AHB-lite bus signals.

Processor accesses and debug accesses to external AHB peripherals are implemented over this bus. Because processor AHB access to zero wait state slaves typically take two cycles longer than TCM accesses, instructions and data must be contained in TCM where possible. If on-chip FPGA memory is used for the processor, highest performance is possible if this is TCM memory, rather than SRAM mapped onto the AHB interface.

Processor accesses and debug accesses share the external interface. Debug accesses take priority over processor accesses.

Timing of processor accesses might be changed by the presence of debug accesses. Giving highest priority to debug means that debug cannot be locked-out by a continuously executing stream of core instructions. Because debug accesses tend to be infrequent, debug accesses do not have a major impact on processor accesses.

Any vendor specific components can populate this bus.

If an external AHB peripheral incorrectly deadlocks the AHB bus, the debugger might not be able to halt or access the core registers. Contact your implementation team for FPGA probing tools to debug the system external to the core.

Unaligned accesses to this bus are not supported.

Was this page helpful? Yes No