ARM Cortex-M

A very common type of 32-bit MCU is the ARM Cortex-M family. It includes the M0, M0+, M1, M3, M4, M7, M23, and M33, with a number of them having a floating point unit (FPU) option for increased floating point performance.

Not only are they used as standalone MCUs, they are also commonly integrated into System-on-Chip (SoC) devices to provide specific functionality, such as touchscreen, sensor, or power management functionality. As Arm Holdings doesn't manufacture any MCUs themselves, many third-party manufacturers have licensed the designs, sometimes making their own modifications and improvements.

Here is a brief overview of these MCUs:

The Thumb instruction sets are compact, 16-bit-length instructions, making them ideal for embedded, resource-restricted systems. Other ARM microprocessor families can also support this Thumb instruction set in addition to the 32-bit instruction set.