FreeRTOS FAQ Contents
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How to get the most from the FreeRTOS support forum

My application does not run, what could be wrong?

Amazon
Why have Amazon taken stewardship of FreeRTOS?
What is “Amazon FreeRTOS”, and how does it differ from “FreeRTOS”?
Do I have to be an Amazon Web Services (AWS) customer to use FreeRTOS?
Can I use FreeRTOS to connect to any cloud service?
Are Amazon also investing in the FreeRTOS kernel as a standalone component?
Have Amazon forked FreeRTOS?
What about the FreeRTOS.org website?

What Is This All About?
What is a Real Time Operating System (RTOS)?
What is a Real Time Kernel?
What is a Real Time Scheduler?
How do I use FreeRTOS?
How do I get started?
Why use an RTOS?

Testing
How is FreeRTOS tested?
What are the mtCOVERAGE_TEST_MARKER() macros?

API
Why are there so many API functions?
Why is there a separate API for use in interrupts?
Why do APIs for use in ISRs set xHigherPriorityTaskWoken rather than actually perform a context switch?
Why are semaphores as large as queues?
How do I use semaphores efficiently?
Why can’t a task delete itself by exiting its implementing function?

Ports
Will FreeRTOS run under Windows?
Are the NNN development tools supported?
Is the NNN microcontroller supported?
How do I create a new port?
What is the difference between an official port, and an unsupported port?

Memory Usage, Boot Times, Context Switch Times
How much RAM does FreeRTOS use?
How much ROM does FreeRTOS use?
How long does FreeRTOS take to boot?
How long does a context switch take?
Why do queues use that much RAM?
How can I reduce the amount of RAM used?
How is RAM allocated to tasks?
How is RAM allocated to queues?
How big should a task stack be?

Licensing
Can I use FreeRTOS in a commercial project?
Do I have to give away my application source code if I use FreeRTOS?

Scheduling
How are tasks of equal priority scheduled?
How are tasks that share the idle priority scheduled?

ISR’s
Can a context switch occur within an ISR?
How do I write an RTOS safe ISR?
Can interrupts be nested?




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Latest News

FreeRTOS v10.2.1 is available for immediate download. MIT licensed, includes 64-bit RISC-V, NXP Cortex-M33 demo & Nuvoton Cortex-M23 demo & STM32H745 dual core (AMP) demo.

New MIT licensed IoT MQTT and IoT Task Pool libraries now available. Includes demo projects.

View a recording of the “OTA Update Security and Reliability” webinar, presented by TI and AWS.

Careers

FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners
ARM Connected RTOS partner for all ARM microcontroller cores
Espressif ESP32
IAR Partner
Microchip Premier RTOS Partner
Renesas
STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0
Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers
OpenRTOS and SafeRTOS
Xilinx Microblaze and Zynq partner

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