AWS FreeRTOS

FreeRTOS includes libraries for connectivity, security, and over-the-air (OTA) updates. FreeRTOS also includes demo applications that show FreeRTOS features on qualified boards.

FreeRTOS is an open-source project. You can download the source code, contribute changes or enhancements, or report issues on the GitHub site at https://github.com/FreeRTOS/FreeRTOS.

FreeRTOS - Architecture

FreeRTOS contains two types of repositories

single library repositories
- Each single library repository contains the source code for one library without any build projects or examples.
package repositories
- Package repositories contain multiple libraries, and can contain preconfigured projects that demonstrate the library’s use.

FreeRTOS Kernel concepts

The FreeRTOS kernel is a real-time operating system that supports numerous architectures.

Basic components including:

A multitasking scheduler.
Multiple memory allocation options (including the ability to create completely statically-allocated systems).
Intertask coordination primitives, including task notifications, message queues, multiple types of semaphore, and stream and message buffers.
upport for symmetric multiprocessing (SMP) on multi-core microcontrollers.

No `malloc()` but `pvPortMalloc`

When RTOS objects are created dynamically, using the standard C library malloc() and free() functions is not always appropriate for a number of reasons:

They might not be available on embedded systems.
They take up valuable code space.
They are not typically thread-safe.
They are not deterministic.
For these reasons, FreeRTOS keeps the memory allocation API in its portable layer.