Communication interfaces (I2C, SPI, UART, etc.) are some of the most commonly used microcontroller peripherals in embedded systems. In this introductory article, we will look at how low-level drivers for such peripherals can be used in FreeRTOS. Polled Drivers vs Interrupt-driven Drivers Based on the method used for getting information on events (e.g errors, operation
In this article, we will take a look at the software timers in FreeRTOS. A software timer allows a function to be executed at a set time in the future.FreeRTOS - RTOS software timer functionality and features description The function that is executed is referred to as a timer's callback function. The interval between starting
FreeRTOS is one of the most widely used open-source real-time operating systems (RTOS). In this article, we will look at a very simple FreeRTOS program: a push-button will enable/disable the blinking of an LED. The program is developed and tested using the LPCXpresso54102 board with NXP's LPC54102 microcontroller. The program can be easily adapted for
Real-time operating systems (RTOS) allows us to develop complex embedded systems. By using self-contained tasks (threads) each with their own context we can implement programs with multitasking behavior using a single CPU. Passing information between these tasks (inter-task communication) is an important aspect when designing an embedded application using an RTOS. We can say that
Designing an embedded system that employs a real-time operating system (RTOS) with multitasking behavior means that there will be resources that must be shared between the tasks. These shared resources (e.g peripheral modules, data structures, communication interfaces, etc.) by their nature do not support multiple concurrent accesses. Accessing them without any rules in place may
In our article covering the scheduling algorithms of real-time operating systems (RTOS), we stated that they can run tasks in such a way that leaves the impression of a multitasking behavior. This is achieved by giving the RTOS the capability to interrupt a currently executing task and to start executing another one. At some point
We already introduced the basic concepts of real-time operating systems (RTOS) and now we will take a deeper look into one of the most important things when designing an embedded system using an RTOS - the scheduling of the tasks and the algorithms that are used. Scheduling Process Scheduling is the process of deciding which
Embedded systems are microcontroller-based systems that are designed to perform specific functions such as reading sensor data, responding to external events, communicating with other systems, controlling processes, etc. The tricky part is to make the distinction of what exactly qualifies such a system as real-time. Aren't all embedded systems operating in real-time? In order for
