Real-Time Operating Systems (RTOS)

All major vendors of Real-Time Operating Systems (RTOS) support ARM architecture.

Many embedded systems require software to respond to inputs and events within a defined short period. Such systems can be categorized as hard real-time, where missing a response deadline is unacceptable (for example an anti-lock braking system), and soft real-time, where hitting a deadline is desirable but not critical. In both types of system, a degree of determinism is important.

RTOS is designed to control an embedded system and deliver the real-time responsiveness and determinism required by the controlled device. Applications run under the control of the RTOS, which schedules allocated CPU time.

In modern systems, a RTOS consists not only of a real-time kernel, but also higher-level functions such as device management (USB, UART, Ethernet, LCD, etc.), file systems, protocol stacks (CAN, TCP/IP, HTTP, etc.) and graphical user interfaces (GUI).

ARM Advantage

The ARM architecture is particularly well suited to the real-time and deterministic requirements of embedded systems, and the implementation of RTOS running on those systems:

• Small code footprint, allowing an RTOS to run from onboard memory
• Fast interrupt response to reduce context switching overhead
• Semaphore support via exclusive load-and-store instructions
• SVC instructions and exceptions to support privileged state operation for the RTOS kernel
• Separate stack pointers for each processor mode for easier memory management
• Sleep modes to minimize power consumption

Whatever your application, you are sure to find a comprehensive list of RTOS vendors who support the ARM architecture.

RTOS Vendors

The ARM architecture is supported by all popular RTOS vendors in the embedded market. Below is a table showing the RTOS companies, their products, and an indication of which ARM processor families they currently support:

Company	RTOS	Cortex-			Classic
		A	R	M	ARM11	ARM9	ARM7
Altreonic	OpenComRTOS			•
American Megatrends	MegaRAC					•
AVIX-RT	AVIX			•
B Labs	Codezero Embedded Hypervisor	•			•	•
CMX Systems	CMX-RTX	•	•	•	•	•	•
Code Time Technologies	Code Time RTOS			•
CooCox	CooCox CoOS			•
Dalian uLoong	μTenux Open Source Embedded OS			•		•	•
DDC-I Inc	HeartOS					•	•
eCosCentric	eCos	•	•	•	•	•	•
eForce	µC3			•			•
Enea Software AB	OSE			•	•	•	•
eSOL	eT-kernel, PrKERNEL	•			•	•	•
Evidence SRL	ERIKA Enterprise (OSEK)			•			•
Express Logic	ThreadX	•	•	•	•	•	•
FreeRTOS.org	FreeRTOS			•		•	•
Green Hills Software	INTEGRITY, VelOSity	•	•	•	•	•	•
Hopen Software Eng Co Ltd	Hopen RTOS	•			•	•	•
HYCTRON Electronic Ltd	Embedded OS				•	•
KADAK	AMX RTOS				•	•	•
Keil	Keil RTX			•		•	•
LynuxWorks	LynxOS, Blue Cat	•				•	•
Mentor Graphics	Nucleus ReadyStart	•	•	•	•	•	•
Micrium	µC/OS-III			•	•	•	•
Micro Digital Inc	SMX RTOS			•	•	•	•
OBP Research	ReaGOS	•	•	•
OpenSynergy GmbH	COQOS	•				•
Pengutronix	OSELAS		•	•	•	•	•
Phoenix Technologies	HyperSpace					•	•
QNX Software Systems	Neutrino	•			•	•
Quadros Systems	RTXC Quadros	•		•	•	•	•
Quantum Leaps	QP-nano			•		•	•
Radisys	Microware OS-9					•	•
RISC OS Ltd	RISC OS					•	•
Rowebots Research	Unison v4			•
rt-labs AB	rt-kernel			•		•	•
RT-Thread.org	RT-Thread RTOS			•		•	•
SCIOPTA	SCIOPTA	•	•	•	•	•	•
Segger	EmbOS	•		•	•	•	•
Sierraware	SierraOS	•			•
Semihalf	FreeBSD	•				•
SYSGO	PikeOS	•				•
Umicos	Catapult RTOS			•		•
Unicoi Systems	Fusion RTOS						•
Wind River	VxWorks	•			•	•	•
Wittenstein	OpenRTOS, SafeRTOS			•		•	•