ARM R4F Build configuration, Configuration inputs, Software configuration, ARM Architecture

Introduction

3.Programming. The system programmer develops the software required to configure and initialize the processor, and possibly tests the required application software on the processor.

Each of these stages can be performed by a different company. Configuration options are available at each stage. These options affect the behavior and available features at the next stage:

Build configuration

The implementer chooses the options that affect how the RTL source files are pre-processed. They usually include or exclude logic that can affect the area or maximum frequency of the resulting macrocell.

For example, the BTCM interface can be configured to have zero, one (B0TCM) or two (B0TCM and B1TCM) ports. If one port is chosen, the logic for the second port is excluded from the macrocell, although the pins remain, and the second port (B1TCM) cannot be used on that macrocell.

Configuration inputs

The integrator configures some features of the processor by tying inputs to specific values. These configurations affect the start-up behavior before any software configuration is made. They can also limit the options available to the software.

For example, if the build configuration for the macrocell includes both BTCM ports, the integrator can choose how many ports to actually use, and therefore how many RAMs must be integrated with the macrocell. If the integrator only wishes to use one BTCM port, they can connect RAM to the B0TCM port only, and tie the ENTCM1IF input to zero to indicate that the B1TCM is not available.

Software configuration

The programmer configures the processor by programming particular values into software-visible registers. This affects the behavior of the processor.

For example, the enable bit in the BTCM Region Register controls whether or not memory accesses are performed to the BTCM interface. However, the BTCM cannot, and must not, be enabled if the build configuration does not include any BTCM ports, or if the pin configuration indicates that no RAMs have been integrated onto the BTCM ports.

Note

This manual refers to implementation-definedfeatures that are applicable to build configuration options. References to a feature which is included mean that the appropriate build and pin configuration options have been selected, while references to an enabled feature mean one that has also been configured by software.

1.10.3Architectural information

The Cortex-R4 processor conforms to, or implements, the following specifications:

ARM Architecture

This describes:

•The behavior and encoding of the instructions that the processor can execute.

•The modes and states that the processor can be in.

•The various data and control registers that the processor must contain.

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