Functional Overview

Registered HWDATA

The interconnect used within the AHB MC contains combinatorial paths for the write data. To improve the synthesis timing, HWDATA is registered and makes these paths internal to the design.

Big-endian 32-bit mode

The AHB MC supports the option of storing data to memory in big-endian 32-bit mode. Each bridge contains the logic to implement this data mapping depending on the big_endian input tie-off. Figure 2-5shows that if the tie off is asserted then the data buses are reordered.

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Figure 2-5 Big-endian implementation

Removal of AHB error response logic

The internal protocol used within AHB MC supports the concept of errors. However none of the components used ever generate errors. This means that the bridge does not require any logic to generate AHB errors because there are no circumstances when errors can be generated.

2.3.2AHB to APB bridge operation

The internal memory controller has an APB configuration port. The AHB configuration port is mapped to it using an AHB to APB bridge. Figure 2-6 on page 2-11shows that each internal memory controller configuration port has a 4KB address space.

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Copyright © 2006 ARM Limited. All rights reserved.

ARM DDI 0389B

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SMC Networks PL241, AHB SRAM/NOR manual Registered Hwdata, Big-endian 32-bit mode, Removal of AHB error response logic