The heart of the Internet of Things is embedded technology. A microcontroller-powered “thing” can be connected to another through the internet using any IoT network. The majority of Internet of Things (IoT) devices are powered by simple, low-power microcontrollers that lack the resources to operate a typical operating system. Microcontrollers are frequently flashed with simple firmware codes designed to carry out particular tasks. For embedded software, getting online and interacting with cloud services in real time is crucial. For embedded controllers, real-time operating systems (RTOS) are the way to go.
RTOS are superior operating systems that let embedded controllers and processors run large-scale embedded programs in an organized way so that several activities be carried out concurrently on a single core while yet meeting real-time deadlines. With the aid of RTOS, IoT devices may efficiently exchange data in real-time while multitasking embedded activities by connecting to cloud platforms and edge devices.
FreeRTOS is one prominent RTOS. Its widespread adoption among the embedded community can be attributed to its open-source and free nature. There are further FreeRTOS derivatives that are both free and licensed. FreeRTOS makes it possible to experiment with Arduino or ESP boards, which is one of its best features. Additionally, FreeRTOS can be enhanced with new libraries to customize it for a specific application. What FreeRTOS is and why we need it is covered in this essay.
Real-time operating system (RTOS)
An RTOS is a multitasking operating system designed for time-sensitive applications. A real-time operating system (RTOS) executes tasks under time-constrained conditions, where the tasks must be completed between the occurrence of an event and the system’s anticipated response to the event. The latencies of RTOS tasks are precisely matched to their anticipated completion times.
Miniature operating systems, or RTOS, are typically under one megabyte in size. Since they are not full operating systems, these mini OS frequently lack file systems, networking, and command-line interfaces. Nevertheless, they have excellent process, resource, device, and sub-system management capabilities. An RTOS can be event-driven or time-sharing and only permits static memory allocation or dynamic memory allocation carried out by the application program using a deterministic method. Either memory locks are in place, or the memory management unit (MMU) is deactivated. The memory locks reduce jitter and make task latencies predictable by stopping page shifting between physical memory and disk.
A RTOS’s scheduler is intended to follow a deterministic execution pattern. This is helpful for embedded systems where the device has a limited amount of time to react to an event. The kernel space, which boasts performance, is where the threads of the application program run. Due to the application program’s access to the kernel’s source code, data, and stack memory, the kernel may become vulnerable.
An application program under RTOS is written as a collection of independent tasks; a thread of execution is such a task. An RTOS provides user-defined process priorities management with each task assigned a priority. The user-level priorities, also called real-time priorities, are higher than the dynamically allocated priorities to OS functions and the idle priorities assigned to low-priority threads. RTOS preempts lower-priority tasks as a message or event to run a higher-priority task occurs. For tasks with equal priority, a RTOS relies on time slicing of the execution of processes.
RTOS vs. general-purpose OS
The scheduler is made to respond to the user’s currently running program in a conventional operating system. The scheduler in a multi-user operating system is made to guarantee equitable processing time and memory sharing among numerous users. Assigned priorities are given to tasks or application threads in RTOS, and the scheduler is made to finish the task with the highest priority first and by the deadline.
An RTOS may operate in hard real-time or soft real-time. If the RTOS operates under strict time limitations, it is referred to as a complex real-time system. On the other hand, if the RTOS operates predictably while accepting some delays, it is referred to as a soft real-time system. An illustration of a hard real-time system is medical equipment that can save lives. An illustration of a soft real-time system is the AAVideo decoder.
Why use RTOS?
Hard real-time systems typically need real-time operating systems. The only other situation in which an RTOS might be used is in multitasking-intensive embedded devices. The majority of embedded systems are made to carry out a particular, very narrow task using only bare metal programming. However, a lot of embedded applications call for inter-process communication or the simultaneous execution of several activities. When compared to creating an inter-process routine and writing a custom scheduler, RTOS is the most practical choice in this situation.
Aside from real-time processing and multitasking, RTOS has other advantages for embedded applications. The ideal method for managing a complicated or big application is RTOS. It makes ensuring that the embedded system completes top-priority activities within time restrictions in order to properly address any risks, defects, or failures that might arise. This can be accomplished with a simpler and shorter application code thanks to RTOS. It enables the division of application code into autonomous jobs with known latency. The maintenance of RTOS-based embedded systems is easier. Less interdependencies exist between the modules, and they frequently rely on kernel features rather than the underlying hardware. This means that RTOS-based applications are frequently unaffected by changes in hardware, such as those to the processor or a peripheral.
The majority of the code is reusable because the application is set up as a collection of separate tasks. Because of defined test procedures, it is simpler to test systems that run RTOS. Hardware interfaces may not even be needed for the testing.
What is FreeRTOS?
Real-time operating system for microcontrollers and other tiny processors called FreeRTOS is free and open-source. Richard Barry created it in 2003, and his business Real Time Engineers Ltd. maintained it till 2017. Amazon Web Services assumed control of the FreeRTOS project in 2017. A number of IoT support libraries are included in the Amazon FreeRTOS derivation, which is an expansion of the original FreeRTOS kernel. The term “FreeRTOS” is commonly used to refer to Amazon FreeRTOS.
The majority of microcontrollers don’t need an entirely implemented RTOS. FreeRTOS is a real-time scheduler with a TCP/IP stack but not a complete RTOS. For handling inter-process communication (IPC) and coordinating tasks with IPCs, it is frequently employed as an RTOS kernel. FreeRTOS lacks a file system, virtual memory, and security paradigm. If necessary, FreeRTOS can have add-on libraries added to it to offer other functionality like networking and command line interpreters.
Why FreeRTOS?
FreeRTOS is essentially a real-time scheduler with a kernel made up of just three.c files, written in the C programming language. The FreeRTOS kernel’s modest size is what makes it ideal for microcontrollers. More than 40 architectures, including ARM, can use FreeRTOS. It is open-source and distributed under an MIT license, making it accessible to everyone. It can even be altered to run on unique or new hardware platforms. Due to the open-source nature of the source code, embedded engineers can examine the kernel code as needed to solve a problem. Even though FreeRTOS does not fully implement RTOS, the kernel makes sure that strict real-time requirements are met.
FreeRTOS can be embedded in an application without exposing proprietary source code. It provides built-in tracing support, a TCP/IP stack, and a command-line interpreter. Being a trusted kernel evolved by a collaboration of more than 15 chip manufacturers, it is designed to be readily integrated into IoT applications. It can be ported to microcontroller-based evaluation boards and tested with pre-configured demos that greatly accelerate the time to market. Amazon offers IoT device tester, a test automation tool that lets self-test whether a hardware platform supports FreeRTOS. FreeRTOS has evolved to interoperate with Amazon Web Services (AWS) and comes with all possible IoT capabilities. The RTOS can be updated over the air (OTA) for installing security patches and add-on libraries whenever required.
Extending FreeRTOS
Add-on libraries can be used to extend FreeRTOS’s RTOS capabilities. A complete lightweight TCP/IP stack can be implemented using the FreeRTOS+TCP package. In order to communicate with external devices, the FreeRTOS+IO library extends FreeRTOS with POSIX-like interfaces. We can now track the RTOS’s real-time activity thanks to the FreeRTOS+Trace package, which now offers tracing functionality. The FreeRTOS+CLI library aids in adding an operating system command line interface.
Applications of FreeRTOS
IoT applications can benefit greatly from FreeRTOS, especially if they must communicate with AWS. It is widely used in industrial and consumer market commercial applications. Since it is a simple real-time scheduler, FreeRTOS is frequently used in industrial hard real-time devices. Microcontrollers are commonly used to control a variety of consumer goods, including smart lights, wearables, and home appliances.
FreeRTOS alternatives
FreeRTOS might not always be the best option. This is particularly true when a device genuinely needs an implementation of an RTOS in its entirety. These programs can need a file system, virtual memory, or a sophisticated user interface. An embedded Linux variant works in these circumstances. EmbOS, Yocto, Zephyr, ThreadX, Nucleus, Keil RTX, SafeRTOS, and other alternative RTOS may be appropriate in this circumstance. FreeRTOS will be overkill for applications that don’t deal with real-time limitations or multitasking. Such applications require bare metal programming to be resolved.
Getting started with FreeRTOS on Arduino or ESP
Widely utilized in commercial embedded applications, FreeRTOS is open-source and totally free. The fact that it can be uploaded to well-known microcontroller boards like Arduino, ESP, and STM32 is its biggest feature. Therefore, anyone can easily get started and test FreeRTOS on well-known microcontroller devices.
In conclusion, RTOS is a powerful and flexible real-time operating system that can provide the necessary tools and features to build complex embedded systems. Its simplicity, portability, and scalability make it an excellent choice for a wide range of projects, from simple microcontroller-based applications to complex IoT devices. By understanding the basic concepts and features of RTOS, developers can build reliable, efficient, and secure systems that meet the most demanding requirements. Whether you are a beginner or an experienced embedded developer, learning RTOS can help you take your projects to the next level and unleash the full potential of your hardware.
Moreover, FreeRTOS has a vibrant community of developers and users who contribute to its development and share their knowledge and experience through forums, blogs, and tutorials. This community-driven approach ensures that FreeRTOS stays up-to-date with the latest hardware and software technologies and provides support and resources for developers to overcome any challenges they may face. Additionally, FreeRTOS has a rich ecosystem of tools, libraries, and integrations that can simplify the development and deployment of real-time applications. From development boards and debuggers to cloud platforms and communication protocols, FreeRTOS can integrate with a wide range of tools and technologies to provide a seamless development experience. Overall, FreeRTOS is an essential tool for anyone who wants to develop real-time embedded systems and unleash the full potential of their hardware.