ARM Cortex-R

ARM Cortex-R
	Mediatek MT6280A ARM Cortex-R4
General information
Designed by	Arm Ltd.
Architecture and classification
Instruction set	ARMv7-R, ARMv8-R,; ARM (32-bit),; ARM (64-bit),; Thumb (16-bit)

Last updated November 24, 2023

The ARM Cortex-R is a family of 32-bit and 64-bit RISC ARM processor cores licensed by Arm Ltd. The cores are optimized for hard real-time and safety-critical applications. Cores in this family implement the ARM Real-time (R) profile, which is one of three architecture profiles, the other two being the Application (A) profile implemented by the Cortex-A family and the Microcontroller (M) profile implemented by the Cortex-M family. The ARM Cortex-R family of microprocessors currently consists of ARM Cortex-R4(F), ARM Cortex-R5(F), ARM Cortex-R7(F), ARM Cortex-R8(F), ARM Cortex-R52(F), ARM Cortex-R52+(F), and ARM Cortex-R82(F).

Overview

32-bit
Year	Core
2011	Cortex-R4(F)
2011	Cortex-R5(F)
2011	Cortex-R7(F)
2016	Cortex-R8(F)
2016	Cortex-R52(F)
2022	Cortex-R52+(F)

64-bit
Year	Core
2020	Cortex-R82(F)

The ARM Cortex-R is a family of ARM cores implementing the R profile of the ARM architecture; that profile is designed for high performance hard real-time and safety critical applications. It is similar to the A profile for applications processing but adds features which make it more fault tolerant and suitable for use in hard real-time and safety critical applications.

Real time and safety critical features added include:

Tightly coupled memory (uncached memory with guaranteed fast access time)
Increased exception handling in hardware
Hardware division instructions
Memory protection unit (MPU)
Deterministic interrupt handling as well as fast non-maskable interrupts
ECC on L1 cache and buses
Dual-core lockstep for CPU fault tolerance

The Armv8-R architecture includes virtualization features similar to those introduced in the Armv7-A architecture. Two stages of MPU-based translation are provided to enable multiple operating systems to be isolated from one another under the control of a hypervisor.

Prior to the R82, introduced on 4 September 2020,^[1] the Cortex-R family did not have a memory management unit (MMU). Models prior to the R82 could not use virtual memory, which made them unsuitable for many applications, such as full-featured Linux.^[1] However, many real-time operating systems (RTOS), with an emphasis on total control, have traditionally regarded the lack of an MMU as a feature, not a bug.^[1] On the R82, it may be possible to run a traditional RTOS in parallel with a paged OS such as Linux, where Linux takes advantage of the MMU for flexibility, while the RTOS locks the MMU into a direct translation mode on pages assigned to the RTOS so as to retain full predictability for real-time functions.^[1]

ARM license

ARM Holdings neither manufactures nor sells CPU devices based on its own designs, but rather licenses the core designs to interested parties. ARM offers a variety of licensing terms, varying in cost and deliverables. To all licensees, ARM provides an integratable hardware description of the ARM core, as well as complete software development toolset and the right to sell manufactured silicon containing the ARM CPU.

Silicon customization

Integrated device manufacturers (IDM) receive the ARM Processor IP as synthesizable RTL (written in Verilog). In this form, they have the ability to perform architectural level optimizations and extensions. This allows the manufacturer to achieve custom design goals, such as higher clock speed, very low power consumption, instruction set extensions, optimizations for size, debug support, etc. To determine which components have been included in a particular ARM CPU chip, consult the manufacturer datasheet and related documentation.

Applications

The Cortex-R is suitable for use in computer-controlled systems where very low latency and/or a high level of safety is required. An example of a hard real-time, safety critical application would be a modern electronic braking system in an automobile. The system not only needs to be fast and responsive to a plethora of sensor data input, but is also responsible for human safety. A failure of such a system could lead to severe injury or loss of life.

Other examples of hard real-time and/or safety critical applications include:

Medical device
Programmable logic controller (PLC)
Electronic control units (ECU) for a wide variety of applications
Robotics
Avionics
Motion control

Related Research Articles

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<span class="mw-page-title-main">ARM Cortex-M</span> Group of 32-bit RISC processor cores

The ARM Cortex-M is a group of 32-bit RISC ARM processor cores licensed by ARM Limited. These cores are optimized for low-cost and energy-efficient integrated circuits, which have been embedded in tens of billions of consumer devices. Though they are most often the main component of microcontroller chips, sometimes they are embedded inside other types of chips too. The Cortex-M family consists of Cortex-M0, Cortex-M0+, Cortex-M1, Cortex-M3, Cortex-M4, Cortex-M7, Cortex-M23, Cortex-M33, Cortex-M35P, Cortex-M52, Cortex-M55, Cortex-M85. A floating-point unit (FPU) option is available for Cortex-M4 / M7 / M33 / M35P / M52 / M55 / M85 cores, and when included in the silicon these cores are sometimes known as "Cortex-MxF", where 'x' is the core variant.

The ARM Cortex-A is a group of 32-bit and 64-bit RISC ARM processor cores licensed by Arm Holdings. The cores are intended for application use. The group consists of 32-bit only cores: ARM Cortex-A5, ARM Cortex-A7, ARM Cortex-A8, ARM Cortex-A9, ARM Cortex-A12, ARM Cortex-A15, ARM Cortex-A17 MPCore, and ARM Cortex-A32, 32/64-bit mixed operation cores: ARM Cortex-A35, ARM Cortex-A53, ARM Cortex-A55, ARM Cortex-A57, ARM Cortex-A72, ARM Cortex-A73, ARM Cortex-A75, ARM Cortex-A76, ARM Cortex-A77, ARM Cortex-A78, ARM Cortex-A710, and ARM Cortex-A510 Refresh, and 64-bit only cores: ARM Cortex-A34, ARM Cortex-A65, ARM Cortex-A510 (2021), ARM Cortex-A715, ARM Cortex-A520, and ARM Cortex-A720.

PX5 RTOS is a real-time operating system (RTOS) designed for embedded systems. It is implemented using the ANSI C programming language.

References

1 2 3 4 Salter, Jim (9 September 2020). "Arm's new Cortex-R82 is its first 64-bit real-time processor". arstechnica.com. Ars Technica . Retrieved 11 September 2020.

External links

ARM Cortex-R official documents

ARM Cortex-R official website

ARM Core	Bit Width	ARM Website	ARM Technical Reference Manual	ARM Architecture Reference Manual
Cortex-R4(F)	32	Link	Link	ARMv7-R
Cortex-R5(F)	32	Link	Link	ARMv7-R
Cortex-R7(F)	32	Link	Link	ARMv7-R
Cortex-R8(F)	32	Link	Link	ARMv7-R
Cortex-R52(F)	32	Link	Link	ARMv8 ARMv8-R
Cortex-R52+(F)	32	Link	Link	ARMv8-R
Cortex-R82(F)	64	Link	Link	ARMv8-R (AArch64)

Migrating

Migrating from MIPS to ARM – arm.com
Migrating from PPC to ARM – arm.com
Migrating from IA-32 (x86-32) to ARM – arm.com

Other

CORTEX-R versus CORTEX-M

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[Salter2020-1] 1 2 3 4 Salter, Jim (9 September 2020). "Arm's new Cortex-R82 is its first 64-bit real-time processor". arstechnica.com. Ars Technica . Retrieved 11 September 2020.

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