Hello everyone, I am Pi Zi Heng, a serious technical person. Today, I will introduce to you the first Cortex-M microcontroller.

1. Born to Glory: The Origin of ARM Cortex-M Processors

ARM introduced the ARMv7 architecture in 2004, abandoning the previous naming convention of “ARM + number” (processors before ARM11 are collectively referred to as the classic processor series), and reintroduced the Cortex naming convention, subdividing the Cortex series into three categories:

• Cortex-A Series: Application processor cores for performance-intensive systems.
• Cortex-R Series: High-performance cores for real-time applications.
• Cortex-M Series: Microcontroller cores for various embedded applications.

The Cortex-M series is primarily designed to replace the classic ARM7 series processors (such as the ARM7TDMI based on the ARMv4 architecture). The Cortex-M architecture is three generations ahead of ARM7, with significant performance improvements, so new designs recommend using Cortex-M. For details on migrating from ARM7 to Cortex-M, refer to the ARM official guidelines for the ARM7 processor series. If you want to learn more about the evolution of ARM core versions, you can check out my other blog post, “Chronology of ARM Core Architecture (Simplified Version)”.

2. Gaining Wings: The ARM Cortex-M Processor Family

Since ARM launched the first Cortex-M3 processor based on the ARMv7M architecture in 2004, the Cortex-M processor family has developed to the Cortex-M33 as of 2018. Below are the release times and characteristics of each processor:

• Cortex-M3: Released in October 2004, based on ARMv7M architecture, a high-performance and low-cost ARM processor for the standard embedded market.
• Cortex-M1: Released in March 2007, based on ARMv6M architecture, specifically designed for ARM processors implemented in FPGA.
• Cortex-M0: Released in February 2009, based on ARMv6M architecture, the smallest area and lowest power consumption ARM processor.
• Cortex-M4: Released in February 2010, based on ARMv7M architecture, adding floating-point and DSP capabilities to meet the needs of the digital signal control market.
• Cortex-M0+: Released in March 2012, based on ARMv6M architecture, an ARM processor that further reduces power consumption based on M0.
• Cortex-M7: Released in September 2014, based on ARMv7M architecture, an ARM processor that further enhances computing performance and DSP processing capability based on M4, mainly targeting the high-end embedded market.
• Cortex-M23: Released in November 2016, based on ARMv8M baseline architecture, an ARM processor that adds TrustZone security feature support based on M0/M0+, meeting IoT security requirements.
• Cortex-M33: Released in November 2016, based on ARMv8M mainline architecture, an ARM processor that adds TrustZone security feature support based on M3/M4, meeting IoT security requirements.
• Cortex-M35P: Released in May 2018, based on ARMv8M mainline architecture, an ARM processor that adds capabilities to defend against physical attacks based on M33, meeting IoT security requirements.

For specific features of ARM Cortex-M, see the official introduction to ARM Cortex-M core series.

Note: Each Cortex-Mx processor does not have only one version. For example, the Cortex-M3 has had four versions so far: r0p0, r1p0, r1p1, r2p0, with minor differences between versions. For details, refer to the ARM Cortex-M series core documentation.

3. First Glimpse: The First Cortex-Mx Microcontroller Product

ARM provides powerful Cortex-M processors, and now it is time for major semiconductor OEMs to showcase their skills. It is well known that seizing market opportunities is crucial. Let us see who first released the first ARM Cortex-Mx microcontroller:

• In March 2006, Luminary Micro (acquired by TI in 2009) was the first to launch the Stellaris LM3S series MMCU based on the ARM Cortex-M3 processor, but it received little response at the time. It wasn’t until June 2007 that ST also launched the STM32 F1 series MCU based on the same core, which made it shine.
• In March 2009, NXP Semiconductors was the first to launch the LPC1100 series MCU based on the ARM Cortex-M0 processor.
• In August 2010, Freescale Semiconductor (acquired by NXP in 2015) was the first to launch the Kinetis K series MCU based on the ARM Cortex-M4 processor.
• In November 2012, NXP Semiconductors continued to be the first to launch the LPC800 series MCU based on the ARM Cortex-M0+ processor.
• In September 2014, ST was the first to launch the STM32 F7 series MCU based on the ARM Cortex-M7 processor.
• In June 2018, Microchip was the first to launch the SAM L1x series MCU based on the ARM Cortex-M23 processor.

4. Competing for Dominance: Market Share of Cortex-Mx Microcontroller Products

Sometimes, seizing the opportunity does not guarantee lasting success; it is easier to conquer than to defend. The Cortex-M microcontroller market has developed to this day, with various semiconductor manufacturers competing for market share:

• STMicroelectronics: Focused on general market share and product price advantages, its STM32 product line encompasses the entire Cortex-M family, showing indifference to competitors’ merger actions.
• NXP Semiconductors: Focused on the automotive semiconductor market, boasting the broadest product line. After acquiring Freescale, its Kinetis product line (Cortex-M0+/4/7) and LPC product line (Cortex-M0/0+/3/4) have integrated the widest product line.
• Cypress Semiconductor: Focused on the memory market, leading in total product count. After acquiring Spansion and Broadcom’s IoT division, it has created the highest number of products.

In addition, some well-known semiconductor manufacturers have gradually fallen behind in the competition for market share in Cortex-M products, such as Texas Instruments (TI), which acquired Luminary. Its strong computing power in DSP products and ultra-low power advantages of MSP430 products have led it to not fully promote Cortex-M products. Another example is Atmel, the dominant player in the 8/16-bit MCU era (acquired by Microchip in 2016), whose advantages in 8051 and AVR products led to a missed opportunity in the Cortex-M battle.

The Cortex-M processors continue to evolve, and the 32-bit microcontroller market is ever-changing. No one knows who will prevail next.