Cortex-R Series Programmer's Guide now available

The ARM® Cortex®-R family is perhaps the unsung hero of the ARM powered world, quietly running infrastructure from Hard Disk Drive and Solid State Drive controllers, through to mobile phone baseband processing and even automotive ABS controllers. While not having the all-out performance of the Cortex-A series application processors, the Cortex-R family of processors provide several key benefits for systems requiring hard, real-time performance.

The main differences between application processors and real-time processors are:

• Deterministic timing - A system is said to be real-time if the total correctness of an operation depends not only on its logical correctness, but also on the time in which it is performed.
• Latency - There are time constraints to respond to external events. A car braking system must consistently respond within a certain time. The ARM Real-time (R) profile defines an architecture aimed at systems that require deterministic timing and low interrupt latency.
• Safety and reliability - For embedded applications requiring high performance combined with high reliability, Cortex-R series processors provide features such as soft and hard error management, redundant dual-core systems using two cores in lock-step, and Error Correcting Codes (ECC) on all external buses.

The new ARM Cortex-R Series Programmer’s Guide extends the software development series of programming guides available from ARM by covering Cortex-R series processors conforming to the ARMv7-R architecture.

The Cortex-R Series Programmer’s Guide describes the following areas which differ between the Cortex-R series and the Cortex-A and Cortex-M series:

• Floating-point support is available as an option on most Cortex-R series processors to provide computation functionality compliant with the IEEE 754 standard.
• Unlike most other ARM processors, Cortex-R processors typically have some memory that is tightly coupled to the processor core to minimize access time and guarantee latency for critical routines.
• The Cortex-R processors use an MPU instead of an MMU. The MPU enables you to partition memory into regions and set individual protection attributes for each region.
• Fast and consistent interrupt response is a key feature of the Cortex-R processors.
• Fault detection and control can be provided by lock-step processors, ECC on buses and memory, and watchdog timers.

This guide is aimed at anyone writing software for the Cortex-R family of processors, and complements, rather than replaces the existing documentation for the Cortex-R family.

If you’re new to using Cortex-R processors and looking to understand where to begin writing bare-metal programs, or you’re an experienced applications designer wanting to understand how to make the most of the underlying processor, then this guide is a good introduction to the Cortex-R family.

The document is only available to registered ARM customers. See, Cortex-R Series Programmer's Guide.