How to quickly determine whether an MCU can run an RTOS system?
ampheo
To quickly determine whether a microcontroller (MCU) can run an RTOS, follow this checklist based on the RTOS’s minimum hardware requirements and the MCU’s capabilities:
Quick RTOS Compatibility Checklist
| Feature | Minimum Requirement for RTOS | How to Check |
| Core Architecture | 32-bit preferred (ARM Cortex-M*) | Check datasheet (e.g., Cortex-M0/M3/M4) |
| RAM | ≥8 KB (for simple RTOS like FreeRTOS) | Datasheet (SRAM/IRAM size) |
| Flash | ≥32 KB (RTOS kernel + app) | Datasheet (Flash size) |
| Interrupt Controller (NVIC) | Required for preemptive scheduling | Present in all Cortex-M |
| Clock Speed | ≥10 MHz recommended | Check MCU frequency range |
| Timer Peripheral | At least one hardware timer | Check peripherals table |
General Guidelines
| MCU Class | RTOS Friendly? | Notes |
| 8-bit (e.g. AVR) | ⚠️ Limited | Possible, but constrained (e.g. FreeRTOS AVR port) |
| 16-bit (e.g. MSP430) | ⚠️ Possible | Lightweight RTOSs only |
| ARM Cortex-M0/M0+ | ✅ Basic RTOS | Works with small RTOSs like FreeRTOS, Zephyr (low config) |
| Cortex-M3/M4/M7 | ✅✅ Fully RTOS capable | Can run advanced RTOSes (e.g., FreeRTOS, RT-Thread, Zephyr) |
| RISC-V MCUs | ✅ If 32-bit+ | RTOS ports are available for several cores |
Check These in the MCU Datasheet or Reference Manual
Core: Look for ARM Cortex-M or RISC-V 32-bit core.
RAM/Flash: At least 8–16 KB RAM and 32+ KB Flash.
SysTick Timer or Timer peripheral: Needed for OS tick generation.
NVIC (Nested Vectored Interrupt Controller): Required for context switching.
Examples
| MCU | RTOS Capable? | Notes |
| ATmega328P (AVR) | ⚠️ Barely | Can run simple FreeRTOS builds |
| STM32F103C8T6 | ✅✅ Yes | Commonly used with FreeRTOS/RT-Thread |
| STM32F407 | ✅✅ Yes | Cortex-M4F: Excellent for RTOS use |
| ESP32 | ✅✅ Yes | Dual-core, runs FreeRTOS by default |
| Raspberry Pi Pico (RP2040) | ✅ Yes | Can run FreeRTOS, even Zephyr |
Quick Tools to Help
MCU datasheet (check core, RAM/Flash)
Vendor SDKs (e.g. STM32CubeMX, ESP-IDF)
RTOS port list (e.g., FreeRTOS-supported MCUs: https://freertos.org/RTOS_ports.html)
Conclusion
An MCU can run an RTOS if it has:
A 32-bit core
Enough RAM (≥8 KB) and Flash (≥32 KB)
At least one timer
A proper interrupt controller
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