Nathan Jones (@0xc0decafe)

I am an active-duty Army officer and instructor at West Point in the Department of Physics and Nuclear Engineering. I have taught (or am slated to teach) "Cyber Fundamentals", "Digital Logic", "Computer Architecture", "Basic Electrical Engineering", and "Physics 1". I love building fun or useful electronic devices and then teaching people how they work!

You Don't Need an RTOS (Part 4)

Nathan 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.

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.

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.

You Don't Need an RTOS (Part 1)

Nathan Jones April 11, 20248 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.

Make Your Own MCU Boards (2023 Teardown Conference)

Nathan Jones March 7, 2024

Ditch the development boards! Products like the Nucleo development boards serve a wonderful purpose, but they’re ill-suited for projects that need to be small and cheap, such as hobby projects or products just beginning a production run. In this talk (a recording from the 2023 Teardown Conference), you’ll learn how to put a microcontroller or other custom circuit on a PCB a little larger than a stick of gum for less than $3 a board.

Embedded Systems Roadmaps

Nathan Jones November 9, 2023

What skills should every embedded systems engineer have? What should you study next to improve yourself as an embedded systems engineer? In this article I'll share with you a few lists from well-respected sources that seek to answer these questions, with the hope of helping provide you a path to mastery. Whether you've only just finished your first Arduino project or you've been building embedded systems for decades, I believe there's something in here for everyone to help improve themselves as embedded systems engineers.

What does it mean to be 'Turing complete'?

Nathan Jones October 16, 20235 comments

The term "Turing complete" describes all computers and even some things we don't expect to be as powerful as a typical computer. In this article, I describe what it means and discuss the implications of Turing completeness on projects that need just a little more power, on alternative processor designs, and even security.

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