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Getting Started With Zephyr: Saving Data To Files

Mohammed BillooMohammed 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 BillooMohammed 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 WallsColin 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 BillooMohammed 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 BillooMohammed 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.


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

Alan C AssisAlan C Assis July 5, 2023

This hands-on guide peels back the NuttX source tree and shows how to assemble a tailored firmware image. You will learn what each top-level directory does, how to enable apps with menuconfig and search tricks to resolve dependencies, and how to save a defconfig as a reusable board profile so you can rebuild the same image without repeating configuration steps.


Getting Started With Zephyr: Kconfig

Mohammed BillooMohammed 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 (Apache) NuttX RTOS - Part 1

Alan C AssisAlan C Assis June 2, 20234 comments

NuttX RTOS is used in many products from companies like Sony, Xiaomi, Samsung, Google/Fitbit, WildernessLabs and many other companis. So, probably you are already using NuttX even without knowing it, like the you was using Linux on your TV, WiFi router more than 10 years ago and didn't know too! Today you will have the chance to discover a little bit of this fantastic Linux-like RTOS! Are you ready? So, let's get started!


Getting Started With Zephyr: West Manifest Customization

Mohammed BillooMohammed Billoo April 4, 2023

Create a reproducible Zephyr development baseline by customizing a West manifest, so your team avoids surprises from upstream changes. This post walks through forking Zephyr and MCUBoot when you need local changes, adapting Nordic Semiconductor's west.yml as a template, and updating remotes and defaults to point at your forks. Finish by running west init -m --mr to fetch exact revisions.


Dumb Embedded System Mistakes: Running The Wrong Code

Steve BranamSteve Branam February 14, 20212 comments

Running the wrong firmware on a board can waste hours. This post shows a practical marking strategy for embedded Linux that embeds searchable proof-of-life strings into kernel, rootfs, overlay, and application code. It walks through choosing early-boot log points, using compile-time timestamps, and a small shell script to set, find, and clear marks so you can verify builds before flashing.


Getting Started With Zephyr: Bluetooth Low Energy

Mohammed BillooMohammed 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.


Getting Started With Zephyr: Devicetree Bindings

Mohammed BillooMohammed 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 (Apache) NuttX RTOS Part 2 - Looking Inside and Creating Your Customized Image

Alan C AssisAlan C Assis July 5, 2023

This hands-on guide peels back the NuttX source tree and shows how to assemble a tailored firmware image. You will learn what each top-level directory does, how to enable apps with menuconfig and search tricks to resolve dependencies, and how to save a defconfig as a reusable board profile so you can rebuild the same image without repeating configuration steps.


You Don't Need an RTOS (Part 4)

Nathan JonesNathan Jones July 2, 2024

In this fourth (and final!) article I'll share with you the last of the inter-process communication (IPC) methods I mentioned in Part 3: mailboxes/queues, counting semaphores, the Observer pattern, and something I'm calling a "marquee". When we're done, we'll have created the scaffolding for tasks to interact in all sorts of different the ways. Additionally, I'll share with you another alternative design for a non-preemptive scheduler called a dispatch queue that is simple to conceptualize and, like the time-triggered scheduler, can help you schedule some of your most difficult task sets.


What is “real time”?

Colin WallsColin Walls November 7, 20245 comments

The post clarifies the technical meaning of “real time” for embedded systems and contrasts it with the colloquial sense of immediacy. It presents a precise definition: a real-time system’s correctness depends on both logical results and the time at which those results are produced, so missing timing constraints constitutes failure. The article emphasizes determinism — low variance in operation timing — as the key property of real-time systems, and contrasts classic RTOS behavior with general-purpose Linux’s higher timing variance. It also notes that raw CPU overprovisioning can mask nondeterminism in some designs, but is not always practical, reinforcing that real time means predictable timing sufficient for the application, not simply “fast.”


Zephyr: West Manifest For Application Development

Mohammed BillooMohammed Billoo November 25, 2024

In this blog post, I show a simpler way to create custom West manifest files. This technique eliminates the need to duplicate the complex West manifest from upstream Zephyr. I also show how we can use the West manifest to include out-of-tree board and SoC definitions, and include our own out-of-tree drivers.


ANCS and HID: Controlling Your iPhone From Zephyr

Mohammed BillooMohammed Billoo June 11, 2024

In this blog post, we see how certain BLE services can be used to control an iPhone from a Nordic nRF52840 using The Zephyr Project. Specifically, we see how to control certain multimedia functionality using the HID service. Finally, we learn how to use the ANCS client library provided by Nordic in The Zephyr Project to accept or decline an incoming call.


The RTOS minefield

Colin WallsColin Walls February 26, 2024

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


Getting Started With Zephyr: DTS vs DTSI vs Overlays

Mohammed BillooMohammed Billoo October 3, 2025

Devicetrees can be daunting for traditional embedded software engineers that are new to Zephyr. In this blog post, I address these fears and show how navigating Devicetrees can be much easier if you understand that they represent the layered structure of the underlying hardware.


OS influence on power consumption

Colin WallsColin Walls January 27, 20251 comment

Power consumption of an embedded system may be influenced in software in general, but selection of an operating system can be key.


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