Assembly language is best - except when it isn’t
A look at why writing in C often produces more efficient code than hand-written assembly language.
C to C++: 5 Tips for Refactoring C Code into C++
The article titled "Simple Tips to Refactor C Code into C++: Improve Embedded Development" provides essential guidance for embedded developers transitioning from C to C++. The series covers fundamental details necessary for a seamless transition and emphasizes utilizing C++ as a better C rather than diving into complex language features. The article introduces five practical tips for refactoring C code into C++. Replace #define with constexpr and const: Discouraging the use of #define macros, the article advocates for safer alternatives like constexpr and const to improve type safety, debugging, namespaces, and compile-time computation. Use Namespaces: Demonstrating the benefits of organizing code into separate logical groupings through namespaces, the article explains how namespaces help avoid naming conflicts and improve code readability. Replace C-style Pointers with Smart Pointers and References: Emphasizing the significance of avoiding raw pointers, the article suggests replacing them with C++ smart pointers (unique_ptr, shared_ptr, weak_ptr) and using references
Getting Started With Zephyr: Devicetrees
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.
NULL pointer protection with ARM Cortex-M MPU
This post explains how you can set up the ARM Cortex-M MPU (Memory Protection Unit) to protect thy code from dragons, demons, core dumps, and numberless other foul creatures awaiting thee after thou dereference the NULL pointer.
Getting Started With Zephyr: Kconfig
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.
C to C++: Bridging the Gap from C Structures to Classes
In our last post, C to C++: Proven Techniques for Embedded Systems Transformation, we started to discuss the different ways that C++ can be used to write embedded software. You saw that there is no reason to be overwhelmed by trying to adopt complex topics like metaprogramming out of the gate. An important concept to understand is that you can make the transition gradually into C++ while still receiving the many benefits that C++ has to offer.
One of the first...
The Missing Agile Conversation
In this article, we learn about Agile practices and how they use stories as units of development. Stories consist of a brief description, one to a few sentences. They don’t contain details sufficient to allow a developer to implement them. The Agile practice is to defer details as long as possible because conditions may change. When a developer takes on a story to implement, that’s the time for them to perform the work that has been deferred. They do this by having a conversation, a series of specific discussions working closely with the various SME’s (Subject Matter Experts) who have information relevant to the story.
STM32 VS Code Extension Under The Hood
VS Code is becoming the "go to" environment for many developers. Increasingly, toolchain providers are publishing VS Code extensions and ST has recently followed suit. Additionally, CMake is significantly growing in popularity, with many projects adopting it for its ease of use and flexibility. This video shows how the STM32 VS Code extension works under the hood and how to get more out of it.
Specifically, we'll review the CMake files generated by the VS Code extension and how to modify...
Getting Started With Zephyr: West Manifest Customization
IntroductionThe Zephyr Project RTOS (https://zephyrproject.org/), or simply “Zephyr” as it is known colloquially, is an increasingly popular real-time operating system due to its native support for over 450 boards and countless peripherals. When starting with any embedded software project, the first task is to start from a known baseline. This can include cloning a repository from source control, which can be the case with embedded Linux, or downloading a zip file representing a...
Review: Embedded Software Design: A Practical Approach to Architecture, Processes, and Coding Techniques
IntroductionFull disclosure: I was given a copy of this book to review.
Embedded Software Design: A Practical Approach to Architecture, Processes, and Coding Techniques, by Jacob Beningo, is an excellent introduction to strategies for embedded systems design and bringing those designs to fruition. Renowned embedded systems expert Jack Ganssle was the technical reviewer.
This is a practical how-to book on the modern professional practice of embedded systems...
Important Programming Concepts (Even on Embedded Systems) Part V: State Machines
Other articles in this series:
- Part I: Idempotence
- Part II: Immutability
- Part III: Volatility
- Part IV: Singletons
- Part VI: Abstraction
Oh, hell, this article just had to be about state machines, didn’t it? State machines! Those damned little circles and arrows and q’s.
Yeah, I know you don’t like them. They bring back bad memories from University, those Mealy and Moore machines with their state transition tables, the ones you had to write up...
In Memoriam: Frederick P. Brooks, Jr. and The Mythical Man-Month
It is with some sadness that I have read that Fred Brooks has passed away. Brooks (1931 - 2022) worked at IBM and managed a large team developing the IBM System/360 computers in the early 1960s. Brooks was thirty years old at the start of this project. He founded the Computer Science Department at UNC Chapel Hill in 1964, at the age of thirty-three, acting as its department chair for twenty years. He remained at IBM until 1965, however. During this one-year...
Lazy Properties in Python Using Descriptors
This is a bit of a side tangent from my normal at-least-vaguely-embedded-related articles, but I wanted to share a moment of enlightenment I had recently about descriptors in Python. The easiest way to explain a descriptor is a way to outsource attribute lookup and modification.
Python has a bunch of “magic” methods that are hooks into various object-oriented mechanisms that let you do all sorts of ridiculously clever things. Whether or not they’re a good idea is another...
Open-Source Licenses Made Easy with Buildroot and Yocto for Embedded Linux
In this article I will try to explain what are the copyrights/copyleft, what are the popular opensource software licenses, and how to make sure that your Embedded Linux system complies with them using popular build systems ; Buildroot or YOCTO projec
Code Metrics - SLOC Count
Many programmers will start having flashbacks at the title of this article because it contains the words 'metrics' and 'SLOC'. Newer programmers are probably wondering what all of the fuss is about - most probably have no negative connotations with the term 'code metrics' and some may not even know what SLOC is. While there is much baggage associated with metrics and SLOC you shouldn't be afraid to gather fundamentally useful data such as SLOC count from your programming projects...
Lessons Learned from Embedded Code Reviews (Including Some Surprises)
My software team recently finished a round of code reviews for some of our motor controller code. I learned a lot from the experience, most notably why you would want to have code reviews in the first place.
My background is originally from the medical device industry. In the United States, software in medical devices gets a lot of scrutiny from the Food and Drug Administration, and for good reason; it’s a place for complexity to hide latent bugs. (Can you say “
Using XML to describe embedded devices (and speak to them)
This article discusses one of the typical development cycles in embedded device and communication design and presents a possible, light weight solution using the free DClib/netpp framework.
The challengeAssume we're faced with the design of an embedded device, be it a simple SoC unit or a more complex, uC controlled engine with various attached peripherals. From first prototype to the market, the following development cycle is typically walked through:
Learning A New Microcontroller
Contents:- Introduction
- The Peripherals
- System Complexity
- Support Software
- Do It Like Phil
- The Programs
- WET And DRY Code
Getting Started With Zephyr: Devicetrees
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.
Zephyr: West Manifest For Application Development
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.
Coding Step 2 - Source Control
Articles in this series:
- Coding Step 0 - Development Environments
- Coding Step 1 - Hello World and Makefiles
- Coding Step 2 - Source Control
- Coding Step 3 - High-Level Requirements
- Coding Step 4 - Design
When I first started out in programming, version control was not an introductory topic. Not in the least because it required a 'server' (ie, a computer which a teenaged me couldn't afford) but because it seemed difficult and only useful to teams rather than...
Introduction to Microcontrollers - Ada - 7 Segments and Catching Errors
7 Segments the Ada Way
Here is the Ada version (I should say AN Ada version) of the 7 segment multiplexing code presented in the last installment. The hardware now is the STM32F407 Discover board, which is a Cortex M4F board. There are lots of differences in GPIO and timer setup, but if you understoold the previous code in C you should not have much trouble understanding this code in Ada.
As interesting as the Ada approach to the task is the Ada ability to detect...
Simulating Your Embedded Project on Your Computer (Part 1)
Having a simulation of your embedded project is like having a superpower that improves the quality and pace of your development ten times over! To be useful, though, it can't take longer to develop the simulation than it takes to develop the application code and for many simulation techniques "the juice isn't worth the squeeze"! In this two-part blog series, I'll share with you the arguments in favor of simulation (so, hopefully, you too believe in its value) and I'll show you what works (and what doesn't work) to help you to simply, easily, and quickly simulate your embedded project on your computer.
Linux Kernel Development - Part 1: Hello Kernel!
Our very first program in every language or framework usually is the notorious "Hello World" program. For this Linux Kernel Modules Development introduction we will follow the same concept, but instead of the usual "Hello World" we will make a "Hello Kernel!" and you will understand the reason in a few moments. Note that in this article I will not focus on a deep explanation about this topic for the moment, since this is only the introduction.
But before we dive into code we need to have the...
How to make a heap profiler
We'll see how to make a heap profiler. Example code for this post makes up heapprof, a working 250-line heap profiler for programs using malloc/free.
It works out of the box on Linux (tested on "real" programs like gdb and python). The main point though is being easy to port and modify to suit your needs. The code, build and test scripts are at github.
Why roll your own heap profiler?
- It's easy! And fun, if you're that sort of person. What, not reasons enough? OK, how...
C to C++: 5 Tips for Refactoring C Code into C++
The article titled "Simple Tips to Refactor C Code into C++: Improve Embedded Development" provides essential guidance for embedded developers transitioning from C to C++. The series covers fundamental details necessary for a seamless transition and emphasizes utilizing C++ as a better C rather than diving into complex language features. The article introduces five practical tips for refactoring C code into C++. Replace #define with constexpr and const: Discouraging the use of #define macros, the article advocates for safer alternatives like constexpr and const to improve type safety, debugging, namespaces, and compile-time computation. Use Namespaces: Demonstrating the benefits of organizing code into separate logical groupings through namespaces, the article explains how namespaces help avoid naming conflicts and improve code readability. Replace C-style Pointers with Smart Pointers and References: Emphasizing the significance of avoiding raw pointers, the article suggests replacing them with C++ smart pointers (unique_ptr, shared_ptr, weak_ptr) and using references
Jaywalking Around the Compiler
Our team had another code review recently. I looked at one of the files, and bolted upright in horror when I saw a function that looked sort of like this:
void some_function(SOMEDATA_T *psomedata) { asm volatile("push CORCON"); CORCON = 0x00E2; do_some_other_stuff(psomedata); asm volatile("pop CORCON"); }There is a serious bug here — do you see what it is?
Mutex vs. Semaphore - Part 1
It never ceases to amaze me how often I see postings in forums asking the difference between a semaphore and a mutex. Probably what baffles me more is that over 90% of the time the responses given are either incorrect or missing the key differences. The most often quoted response is that of the “The Toilet Example (c) Copyright 2005, Niclas Winquist” . This summarises the differences as:
- A mutex is really a semaphore with value 1
No, no, and no again....
Code Metrics - SLOC Count
Many programmers will start having flashbacks at the title of this article because it contains the words 'metrics' and 'SLOC'. Newer programmers are probably wondering what all of the fuss is about - most probably have no negative connotations with the term 'code metrics' and some may not even know what SLOC is. While there is much baggage associated with metrics and SLOC you shouldn't be afraid to gather fundamentally useful data such as SLOC count from your programming projects...
