The ARM Cortex-M1 processor is a 32-bit reduced instruction set computing (RISC) processor designed by ARM Holdings. It is aimed at embedded and Internet of Things (IoT) applications requiring high efficiency and low power consumption.
Overview
The Cortex-M1 is the smallest and most energy efficient processor in the Cortex-M family, which includes the M0, M3, M4, M7, and M33 processors. It is designed for simple, cost-sensitive embedded applications that need higher performance than an 8- or 16-bit microcontroller but do not require the full capabilities of the Cortex-M3 or M4.
Key features of the Cortex-M1 processor include:
- 32-bit RISC architecture
- 2-stage pipeline
- Up to 50 MHz operating frequency
- Memory Protection Unit (MPU)
- Nested Vectored Interrupt Controller (NVIC)
- Low power sleep modes
The Cortex-M1 is manufactured on a 40nm or smaller process and has a die size under 1mm2. It is designed to deliver better performance per MHz than both ARM7 and Cortex-M0, while minimizing silicon area and power consumption. Typical applications include smart sensors, wearables, IoT nodes, and basic microcontroller-based designs.
Architecture
The Cortex-M1 has a streamlined 32-bit RISC architecture optimized for low-cost embedded applications. Key architectural features include:
- 2-stage pipeline – Instructions are fetched and decoded in the first stage, then executed in the second stage. This is the shortest pipeline in the Cortex-M family.
- Thumb instruction set – Supports a subset of the Thumb-2 instruction set for improved code density.
- Von Neumann architecture – Uses a unified memory architecture for both code and data rather than separate instruction and data buses.
- Fixed 4GB memory map – Entire 4GB address space is visible, supporting both RAM and peripheral registers.
- NVIC – Nested interrupt controller with up to 32 maskable interrupt sources.
- MPU – Optional memory protection unit for protecting different memory regions.
The streamlined architecture results in the smallest silicon implementation of the Cortex-M family. It is optimized for low dynamic power consumption even at maximum processor frequency.
Instruction Set
The Cortex-M1 implements a subset of the Thumb-2 instruction set used across the Cortex-M series. Key features include:
- Highly efficient 16-bit and 32-bit instruction lengths
- Up to 32 general purpose registers
- Load/store architecture with support for C programming
- Conditional execution for branches and skips
- Various arithmetic, logical, and move operations
The instruction set is tuned for Thumb code density rather than ARM code density. A number of features have been removed compared to Cortex-M3/M4 including bit-banding, saturation arithmetic, SIMD instructions, and floating point unit support. This simplifies hardware implementation while still providing good performance for embedded control tasks.
Development Tools
The Cortex-M1 processor can be programmed using the same ARM toolchain as other Cortex-M processors. This includes:
- GCC – open source GNU compiler collection with ARM extensions
- ARM Compiler – ARM’s optimizing C/C++ compiler
- Keil MDK – ARM’s microcontroller development kit for ARM cores
- IAR EWARM – IAR’s embedded workbench IDE and toolchain
These tools allow programming in C and assembly language. Embedded software can be debugged through JTAG/SWD interfaces. ARM provides the M0 DesignStart program for custom silicon vendors to access Cortex-M1 IP and development tools at no upfront cost.
Licensing and Silicon Partners
As a synthesizable IP core, the Cortex-M1 processor is available for licensing to semiconductor companies and SoC developers. It can be targeted to different foundry processes from 40nm down to 28nm. Main licensees include:
- Microchip – EFM32 Tiny microcontroller series
- NXP – LPC800 series Cortex-M0+ MCUs
- Renesas – RA low power MCU family
- Silicon Labs – EFM8 MCUs
- STMicroelectronics – STM32L0 series ultra-low-power MCUs
These microcontrollers combine the Cortex-M1 core with flash memory, peripheral interfaces, radio chips, and other components into compact integrated circuits for IoT edge nodes, wearables, home automation, motor control, and other applications requiring an efficient low-power processor.
Performance
Compared to the Cortex-M0 and older ARM7 cores, the Cortex-M1 delivers significantly higher performance while minimizing power consumption. Some key performance benchmarks include:
- 1.25 DMIPS/MHz – Up to 50% higher than ARM7TDMI
- 1.66 CoreMark/MHz – Up to 2x higher than ARM7 and M0 cores
- 435 CoreMark at 100 MHz – Benchmark score for integer performance
- 0.9 mW/MHz – Ultra low power consumption in active mode
This level of performance is suitable for a wide range of cost-sensitive embedded control applications. The Cortex-M1 achieves better code density than the M0, further improving performance/power for memory-constrained devices.
Conclusion
In summary, the ARM Cortex-M1 processor enables low-cost, energy efficient 32-bit computing for simple embedded devices. Its RISC architecture provides better performance than older 8/16-bit microcontrollers. With extremely compact silicon implementation, the Cortex-M1 is well-suited for IoT endpoints, wearables, wireless sensors, motor control, and other space and power constrained applications.
