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You Don't Need an RTOS (Part 1)

Nathan Jones April 11, 202412 comments

In this first article, we'll compare our two contenders, the superloop and the RTOS. We'll define a few terms that help us describe exactly what functions a scheduler does and why an RTOS can help make certain systems work that wouldn't with a superloop. By the end of this article, you'll be able to: - Measure or calculate the deadlines, periods, and worst-case execution times for each task in your system, - Determine, using either a response-time analysis or a utilization test, if that set of tasks is schedulable using either a superloop or an RTOS, and - Assign RTOS task priorities optimally.


The RTOS minefield

Colin Walls February 26, 2024

Choosing an RTOS is challenging both technically and when assessing suppliers.


Getting Started With Zephyr: Bluetooth Low Energy

Mohammed Billoo January 29, 2024

In this blog post, I show how to enable BLE support in a Zephyr application. First, I show the necessary configuration options in Kconfig. Then, I show how to use the Zephyr functions and macros to create a custom service and characteristic for a contrived application.


Optimizing Real-Time Operating Systems for Efficient Edge Devices

Lance Harvie January 11, 2024

Edge computing has become a crucial technology in today's world, requiring real-time operating systems (RTOS) to provide the necessary capabilities for efficient resource management, optimal performance, and reliable operation of edge devices. Let’s have a look at the key features and benefits of RTOS for edge computing, including the challenges, solutions, best practices, and future trends.

Key Features of RTOS in Edge Environments

RTOS provides several essential features that make it...


Getting Started With Zephyr: Writing Data to EEPROM

Mohammed Billoo December 6, 20235 comments

In this blog post, I show how to implement a Zephyr application to interact with EEPROM. I show how the Zephyr device driver model allows application writers to be free of the underlying implementation details. Unfortunately, the application didn't work as expected, and I'm still troubleshooting the cause.


Getting Started With Zephyr: Saving Data To Files

Mohammed Billoo October 31, 20231 comment

In this blog post, I show how to implement a Zephyr application to mount a microSD card, create a new file on the microSD card, and write data to it. The lessons learned from such an application can be helpful for devices out in the field that need to write data to off-board memory periodically, especially in cases where Internet access may be sporadic.


Getting Started With Zephyr: Devicetree Overlays

Mohammed Billoo September 25, 2023

In this blog post, I show how the Devicetree overlay is a valuable construct in The Zephyr Project RTOS. Overlays allow embedded software engineers to override the default pin configuration specified in Zephyr for a particular board. In this blog post, I use I2C as an example. Specifically, I showed the default I2C pins used for the nRF52840 development kit in the nominal Zephyr Devicetree. Then, I demonstrated how an overlay can be used to override this pin configuration and the final result.


Who needs source code?

Colin Walls August 31, 2023

Many developers feel that the supplying source code is essential for licensed software components. There are other perspectives, including the possibility of it being an actual disadvantage. Even the definition of source code has some vagueness.


Getting Started With Zephyr: Devicetree Bindings

Mohammed Billoo August 16, 2023

This blog post shines some light on how devicetrees are used in The Zephyr Project. Specifically, we understand the mechanisms that enable us to use nodes in the devicetree in the C source files. We use a sample provided in the Zephyr repository itself and work our way through portions of the Zephyr codebase to get insight into the mechanisms that make this possible.


Getting Started With Zephyr: Devicetrees

Mohammed Billoo July 18, 20232 comments

This blog post provides an introduction to the "Devicetree", another unique concept in The Zephyr Project. We learn about the basic syntax of a device tree and how its structure and hierarchy mirror hardware, from the SoC to the final board. We also see how hardware described in a devicetree can be referenced and controlled in the source code of a Zephyr-based application.


Modern Embedded Systems Programming: Beyond the RTOS

Miro Samek April 27, 20167 comments

An RTOS (Real-Time Operating System) is the most universally accepted way of designing and implementing embedded software. It is the most sought after component of any system that outgrows the venerable "superloop". But it is also the design strategy that implies a certain programming paradigm, which leads to particularly brittle designs that often work only by chance. I'm talking about sequential programming based on blocking.

Blocking occurs any time you wait explicitly in-line for...


Getting Started With Zephyr: Kconfig

Mohammed Billoo June 22, 2023

In this blog post, we briefly look at Kconfig, one of the core pieces of the Zephyr infrastructure. Kconfig allows embedded software developers to turn specific subsystems on or off within Zephyr efficiently and control their behavior. We also learn how we can practically use Kconfig to control the features of our application using the two most common mechanisms.


Getting Started With Zephyr: Devicetrees

Mohammed Billoo July 18, 20232 comments

This blog post provides an introduction to the "Devicetree", another unique concept in The Zephyr Project. We learn about the basic syntax of a device tree and how its structure and hierarchy mirror hardware, from the SoC to the final board. We also see how hardware described in a devicetree can be referenced and controlled in the source code of a Zephyr-based application.


Embedded Programming Video Course Teaches RTOS

Miro Samek January 20, 2019

If you'd like to understand how a Real-Time Operating System (RTOS) really works, here is a free video course for you:

RTOS part-1: In this first lesson on RTOS you will see how to extend the foreground/background architecture from the previous lesson, so that you can have multiple background loops running seemingly simultaneously.:

RTOS part-2: In this second lesson on RTOS you will see how to automate the context switch process. Specifically, in this lesson, you will start building...


You Don't Need an RTOS (Part 2)

Nathan Jones May 7, 20246 comments

In this second article, we'll tweak the simple superloop in three critical ways that will improve it's worst-case response time (WCRT) to be nearly as good as a preemptive RTOS ("real-time operating system"). We'll do this by adding task priorities, interrupts, and finite state machines. Additionally, we'll discuss how to incorporate a sleep mode when there's no work to be done and I'll also share with you a different variation on the superloop that can help schedule even the toughest of task sets.


Getting Started With Zephyr: Writing Data to EEPROM

Mohammed Billoo December 6, 20235 comments

In this blog post, I show how to implement a Zephyr application to interact with EEPROM. I show how the Zephyr device driver model allows application writers to be free of the underlying implementation details. Unfortunately, the application didn't work as expected, and I'm still troubleshooting the cause.


You Don't Need an RTOS (Part 3)

Nathan Jones June 3, 20241 comment

In this third article I'll share with you a few cooperative schedulers (with a mix of both free and commercial licenses) that implement a few of the OS primitives that the "Superduperloop" is currently missing, possibly giving you a ready-to-go solution for your system. On the other hand, I don't think it's all that hard to add thread flags, binary and counting semaphores, event flags, mailboxes/queues, a simple Observer pattern, and something I call a "marquee" to the "Superduperloop"; I'll show you how to do that in the second half of this article and the next. Although it will take a little more work than just using one of the projects above, it will give you the maximum amount of control over your system and it will let you write tasks in ways you could only dream of using an RTOS or other off-the-shelf system.


Getting Started With Zephyr: Saving Data To Files

Mohammed Billoo October 31, 20231 comment

In this blog post, I show how to implement a Zephyr application to mount a microSD card, create a new file on the microSD card, and write data to it. The lessons learned from such an application can be helpful for devices out in the field that need to write data to off-board memory periodically, especially in cases where Internet access may be sporadic.


Getting Started with (Apache) NuttX RTOS Part 2 - Looking Inside and Creating Your Customized Image

Alan C Assis July 5, 2023

In the previous article (https://www.embeddedrelated.com/showarticle/1524.p...) we saw how to run NuttX RTOS using the SIMulator. Today we will see how NuttX's directory tree is organized and how to use the menuconfig to enable some applications, including some tricks to search and solve dependencies.

NuttX Directories organization:

If you have previously compiled the Linux kernel or the U-Boot bootloader you will see that the NuttX source tree organization is...


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