ARM products are becoming increasingly diverse, and the naming conventions are becoming more numerous. Many friends have asked: What do ARM cores and architectures mean? What is the relationship between cores and architectures? For example, ARMv7 architecture, what does this architecture refer to? The editor of “Microcontroller and Embedded System Applications” has selected several exciting answers! We hope this helps embedded enthusiasts in designing circuits~
1. ARM Core: From ARM7, ARM9 to Cortex-A7, A8, A9, A12, A15, and then to Cortex-A53, A57, in short, different versions of ARM have different ideas. For example, the Cortex A8 and A9 designed for high speed are both based on the ARMv7a architecture; Cortex M3 and M4 are based on the ARMv7m architecture; the former is the core, while the latter refers to the instruction set architecture.
2. ARM architectures are based on the RISC instruction set, while their cores are merely the hardware architecture that implements this instruction set, a subset of the Thumb-2 instruction set architecture (ISA) that includes all basic 16-bit and 32-bit Thumb-2 instructions, the Harvard architecture, which can execute instructions while loading/storing data, and a three-stage pipeline with branch prediction, etc.
3. It’s like building a house; initially, due to low levels of skill, flat houses were in vogue, which is a type of architecture (V5T). Then, from this flat house architecture, you can design a style with a separate bathroom, which is called the ARM7 core. Then others (chip design companies) who want to build houses can buy your blueprint to build. After a while, someone thinks that just having a separate bathroom is not enough, and they want a small yard! Alright, then ARM meets your demands and releases a style with a small yard (ARM9).
After a long time, this flat house architecture has been modified continuously according to everyone’s needs, and later ARM discovered: now everyone’s ability to build houses has skyrocketed (including technology, design capability, clock frequency), and just building flat houses is no longer sufficient! Alright, ARM, in order to keep these designers busy, launched a style of two or three-story buildings, which is completely different from the flat house design structure, so this is called a new architecture (ARMv6). Similarly, for this building style, ARM also prepared versions with swimming pools and garages (ARM11). Alright, keep modifying until eventually everyone starts to have the ability to build buildings taller than ten stories. ARM, as always, released a new style (ARMv7 architecture). At this point, ARM felt that the previous names were too outdated, like ARM5, ARM6, ARM7—both unappealing and hard to remember, so they decided to give a name that sounds impressive, as we can at least be seen as capable of designing skyscrapers, thus the subsequent cores were named Cortex.
Renaming is just one part; with the release of this architecture, ARM realized that the buildings built using our blueprints were merely residential buildings. What’s the purpose of residential buildings? Affordability (low power consumption). Now it’s different; our blueprints can build not only residential buildings but also military bases and high-end office buildings, which were previously only designed by Intel! To meet these different needs, ARM categorized the designs of this architecture into three series (M series, R series, A series).
The M series is designed for residential buildings because the common people prioritize affordability, so this design typically builds around ten stories (low power consumption); the R series is designed for military bases, which are also not very tall—around ten stories—but the key is to have a rapid response capability for special situations (fast interrupts); finally, the A series is for business magnates, which of course must be high-end and impressive, with high performance and various LED light shows.
Friendly reminder: Embedded friends can reply with keywords like “microcontroller”, “embedded system”, “Internet of Things”, “smart hardware”, “embedded engineer”, “CPU”, “GPU”, “FPGA”, “Linux”, “Android”, “ARM”, etc., to read previous exciting content at any time.
