FreeRTOS

Many MCU projects do not need a full platform at the beginning. Their first problems are concrete:

• the main loop grows and response becomes slower
• UART, sensors, wireless stacks, and storage paths interfere with each other
• ISR code should stay short, but tasks do not know when to run
• one slow peripheral wait delays unrelated logic
• timers, timeouts, retries, and low power become tangled

FreeRTOS often becomes the first RTOS because it separates the concurrency paths that first become unmanageable in bare-metal firmware.

When an MCU project chooses an RTOS for the first time, the first questions are often about size, speed, and API simplicity.

Those questions help, but they are not enough. Choosing an RTOS is not only choosing a scheduler. It is choosing how device software is organized: how tasks are created, how drivers are integrated, where networking and filesystems come from, how board differences are maintained, whether existing C or POSIX-style code can be reused, and whether the team can debug field failures.