Understanding ARM, Cortex-M Cores, and the ARMv8-M Architecture

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Author | strongerHuang

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All processors we use have a set of architectures, for example, the intel Core i5 belongs to the X86 architecture, and the STM32F0 is based on the Cortex-M0 core, which belongs to the ARMv6-M architecture.

Today’s technology is stronger than ever, how much do you know about ARM processors? What are the differences and advantages of the latest ARMv8-M architecture compared to previous architectures?

1

ARM Architecture

ARM has a long development history, starting from the first ARMv1, gradually developing to the well-known ARMv6, ARMv7, and ARMv8.

During ARMv7, the ARM architecture was divided into three types of cores: Cortex-A,Cortex-R,Cortex-M.

Similarly, the ARM architecture is classified into ARMv8-A, ARMv8-R, ARMv8-M.

Here is a diagram for better understanding:

Let me give you some examples:

ARMv8-M: is a type of ARM architecture.

The ARM architecture includes: ARMv1, ARMv2 ··· ARMv8.

ARMv8 is divided into: ARMv8-A, ARMv8-R, ARMv8-M.

Cortex-M3: is an ARM processor core and can be understood as a member of the ARM processor family.

ARM processor cores are divided into classic cores and Cortex cores.

Traditional cores: ARM7, ARM9, etc.

Cortex cores: Cortex-A, Cortex-R, Cortex-M, etc.

STM32: is an ARM core processor chip.

Most STM32 chips are based on the Cortex-M core, with a few including Cortex-A7 (for example: STM32MP1).

2

Cortex-M Core

As of now (October 2020), there are 10 types of ARM’s Cortex-M cores, including: Cortex-M0, M0+, M1, M3, M4, M7, M23, M33, M35P, M55.

Website:

https://developer.arm.com/ip-products/processors/cortex-m

The earliest Cortex-M0 belongs to Armv6-M architecture, while the latest Cortex-M55 is based on the Armv8-M architecture. These architectures have undergone significant development over the years.

These Cortex-M cores are currently popular cores found in many MCUs. As time goes on, the first to be phased out should be the Armv6-M architecture cores, and more architectures will develop.

For example: the M23 is developed based on M0, retaining its advantages and expanding some new features.

3

ARMv8-M Architecture

From the previous description, you should understand that the ARMv8-M architecture has developed step by step from ARMv8.

The development history of ARM architecture: ARMv1, ARMv2 ··· ARMv8.

ARMv8 is divided into: ARMv8-A, ARMv8-R, ARMv8-M.

Have you noticed the newly released Cortex-M processors, which are all trending towards ARMv8-M (of course, there is also a popular RISC-V, which we will not discuss here).

For example: the STM32L5 series uses the M33 core, the LPC55S series uses the M33 core, and the GD32E23 series uses the M23 core, all based on ARMv8-M architecture.

In fact, the ARMv8-M architecture was already released at the ARM Tech Conference in 2015. In today’s rapidly developing Internet of Things, information technology is also very advanced, thus security technology becomes particularly important. ARMv8-M features a new technology called TrustZone (a security technology).

Besides TrustZone technology, ARMv8-M also has more new features compared to the older architectures.

Here is a summary of the content regarding ARM, allowing everyone to have a deeper understanding. In summary, in response to current artificial intelligence and Internet of Things needs, enhancing computing power and increasing security, ARM processors are adding new features in this direction.

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