Scorchers, Part 4: Burned by the Happy Path (Simon Says)
Designs that only work along the happy path break in real use, causing frustration and sometimes safety risks. Jason M. Sachs uses everyday examples from microwaves to car Auto Park logic to show how mutable software and physical state create brittle behavior. He outlines practical firmware fixes such as clear state machines, sensor or user-driven resynchronization, soft-start delays, and a ‘‘Drunken Happy Path’’ fuzzing approach to find real-world failure modes.
Using a board with NuttX RTOS as an RS-485 / Modbus Slave Device
This practical walk-through shows how to turn a NuttX-equipped board into an RS-485 Modbus RTU slave using a cheap MAX485 transceiver and an STM32F4Discovery board. It explains why a simple UART plus a GPIO for DE/RE is enough, why the RP2040 needs special handling, and gives step-by-step configuration in NuttX, wiring for the transceiver, and a quick test using FreeModbus and mbpoll.
On optimizing manual soldering
When faced with manual soldering of thousands of components, speed and efficiency become pivotal. Here are some takeaways from my own experience attempting to optimize such a process.
On hardware state machines: How to write a simple MAC controller using the RP2040 PIOs
Hardware state machines are nice, and the RP2040 has two blocks with up to four machines each. Their instruction set is limited, but powerful, and they can execute an instruction per cycle, pushing and popping from their FIFOs and shifting bytes in and out. The Raspberry Pi Pico does not have an Ethernet connection, but there are many PHY boards available… take a LAN8720 board and connect it to the Pico; you’re done. The firmware ? Introducing Mongoose…
Graphical medicine
Although an appealing user interface is a good option for any device, in medical applications it can be a life saver.
Pay it Forward
A popular car bumper sticker reads, "If you can read this, thank a teacher!" I might say, "If you can read THIS (article on Embedded Related), then you've been blessed with great experiences and/or great educators or volunteers that got you excited about tech and helped you believe that you had a future in this field!" Why not pay it forward by helping other children have those same great experiences? As we enter another season of giving, I hope you consider doing what you can to support the hundreds or thousands of non-profit organizations, educators, and volunteers around the world who are getting kids excited about tech the same way YOU got excited about tech. In this article, I'll share with you a handful of organizations that I know of or donate to that have this mission. How do you like to give back?
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.
What is “real time”?
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.”
Simulating Your Embedded Project on Your Computer (Part 2)
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 the last article, I showed you how to use the terminal (i.e. printf/getchar) to easily make a completely functional simulation. In this article, we'll take simulation to the next level, either in terms of realism (by using virtual hardware) or in terms of user experience (by using a GUI to simulate our hardware, instead of using the terminal).
Blocking == Technical Debt
Blocking code in embedded systems trades quick development for long-term pain, effectively becoming technical debt. This post shows how blocking in Arduino examples and traditional RTOS threads hard-codes sequences and timing, making change and extension expensive. It contrasts blocking kernels with preemptive non-blocking approaches and recommends event-driven Active Objects and frameworks like QP as more scalable alternatives.
Implementing State Machines
Stephen walks through a practical state machine example using a dish-washing analogy to expose common implementation pitfalls and fixes. Starting from a straightforward superloop design he shows how blocking loops, global state, and interrupt races can break behavior, then refactors the code to use scoped enums, non-blocking state actions, and a simple interrupt flag to make embedded state machines safer and more maintainable.
Return of the Delta-Sigma Modulators, Part 1: Modulation
Jason Sachs returns to delta-sigma modulators with a hands-on, code-first treatment that focuses on the DAC side of things. Part 1 walks through first- and second-order kernels, linearized analysis, spectra, and practical coefficient choices while illustrating results with Python simulations. Expect clear rules of thumb for A, R, and B, a derivation of noise shaping behavior, and a useful error bound for RC filtering.
Simulating Your Embedded Project on Your Computer (Part 2)
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 the last article, I showed you how to use the terminal (i.e. printf/getchar) to easily make a completely functional simulation. In this article, we'll take simulation to the next level, either in terms of realism (by using virtual hardware) or in terms of user experience (by using a GUI to simulate our hardware, instead of using the terminal).
C to C++: 3 Reasons to Migrate
Embedded C still powers most devices, but rising system complexity is revealing its limits. In this post Jacob Beningo kicks off a series on moving from C to C++, offering three practical reasons to start the migration now. He argues for an incremental approach that keeps low-level, hardware-dependent code in C while adopting C++ for higher-level, object-oriented application logic so teams can keep shipping during the transition.
Linear Feedback Shift Registers for the Uninitiated, Part II: libgf2 and Primitive Polynomials
Jason Sachs digs into practical finite-field arithmetic for LFSRs, using his libgf2 Python library as the hands-on guide. He shows how to test whether a polynomial is primitive, why that matters for maximal-length sequences, and how the library implements addition, multiplication, exponentiation, and shifts over GF(2). The post is both a math refresher and a code walkthrough for engineers who want to compute with LFSRs instead of just talk about them.
Tolerance Analysis
Jason Sachs walks through practical tolerance analysis by designing a 24V overvoltage detector from the ground up, combining resistor tolerances, temperature coefficients, reference and comparator errors, hysteresis, and dynamic RC behavior. He demonstrates worst-case stacking with real datasheet numbers, shows how solder and mechanical stress affect resistor choice, and sizes filtering so the comparator meets a microsecond-range trip requirement. The article is a hands-on guide full of worked examples and trade-offs for embedded hardware engineers.
Someday We’ll Find It, The Kelvin Connection
Low-ohm measurements will fool your multimeter unless you use Kelvin connections. Jason Sachs walks through four-wire sensing using a current-limited supply and two DMMs, explains thermoelectric and connector-related errors, and shows why schematics and PCB layout must reflect Kelvin sense pads to avoid subtle measurement and circuit problems.
Lost Secrets of the H-Bridge, Part IV: DC Link Decoupling and Why Electrolytic Capacitors Are Not Enough
Switching H-bridges can kick nasty voltage spikes onto the DC link, and a single electrolytic capacitor rarely fixes the problem. Jason Sachs uses simulations and practical PCB layout advice to show how a three-tier decoupling strategy — bulk electrolytic, mid-value ceramics or film, and many small HF bypass capacitors plus PCB plane capacitance — tames spikes, reduces EMI, and avoids harmful resonances when parts and vias are placed correctly.
How FPGAs work, and why you'll buy one
Yossi Kreinin argues that FPGAs are no longer just programmable gate arrays, they are becoming a mainstream programmable acceleration and I/O platform. The article explains how modern FPGAs pair a sea of LUTs and switch boxes with DSP slices, RAMs, and hard CPUs to deliver massive parallelism, deterministic timing, and surprising energy efficiency, and it includes a readable Verilog convolution example to show how this works in practice.
Visual Studio Code Extensions for Embedded Software Development
Visual Studio Code can be a solid embedded development environment, if you equip it with the right extensions. Jacob Beningo walks through tools for Cortex-M debugging, register and RTOS inspection, build system support, formatting, linting, and vendor-specific workflows. It is a practical tour of the extensions that help VS Code feel much less like a general-purpose editor and more like an embedded IDE.
Introduction to Microcontrollers - Further Beginnings
Mike Silva walks through the CPU plumbing every embedded engineer needs to know before writing their first LED blinky. The post explains registers (data, address, stack pointer, link), the fetch-execute cycle, and the main instruction classes such as arithmetic, logic, shifts, branches, and call/return mechanics. Read this to see how C maps to CPU operations and why stack versus link register choices matter.
Absolute Beginner's Guide To Getting Started With Raspberry Pi
Getting started with Raspberry Pi can feel overwhelming. This guide strips the noise and shows the simplest path from unboxing to a working desktop. It recommends buying a preloaded NOOBS microSD to avoid imaging hassles, lists exact parts and suppliers, and walks through booting, recovery, and making a backup. If you want embedded electronics it also lists starter parts and ESD safety tips.
Supply Chain Games: What Have We Learned From the Great Semiconductor Shortage of 2021? (Part 3)
Jason Sachs pulls back the curtain on Moore's Law and the foundry business to explain why the semiconductor shortage exposed brittle economics. He traces how roadmaps, depreciation schedules, and node mix force foundries to juggle expensive new fabs and mature capacity, and shows why leading-edge nodes punch above their volume share in revenue. Engineers get practical insight into how capacity and timing decisions ripple through the supply chain.
Arduino robotics #1 - motor control
Clusterbot is Lonnie Honeycutt's first autonomous robot, built on a tight budget to teach practical motor control. This post explains why you cannot drive motors directly from an Arduino, how to wire and enable the Toshiba TB6612FNG motor driver, and offers hands-on PWM and calibration tips for getting smooth motion from cheap Mabuchi FA-130 toy motors.
Data Hiding in C
You can get C++-style data hiding in plain ANSI C, Stephen Friederichs demonstrates how with a FIFO stack example. He shows opaque pointer typedefs to hide struct layouts, const-qualified handles to catch accidental writes, static file-local functions for private helpers, and a canary field to detect tampering. The pattern keeps the public header stable while letting you change implementations behind the scenes.
How to Estimate Encoder Velocity Without Making Stupid Mistakes: Part II (Tracking Loops and PLLs)
Jason Sachs explains why simple differentiation of encoder counts often fails and how tracking loops and PLLs give more robust velocity estimates. Using a pendulum thought experiment and Python examples, he shows how a PI-based tracking loop reduces noise and eliminates steady-state ramp error, and why vector PLLs with quadrature mixing avoid cycle slips and atan2 unwrap pitfalls in noisy or analog sensing.
Lost Secrets of the H-Bridge, Part IV: DC Link Decoupling and Why Electrolytic Capacitors Are Not Enough
Switching H-bridges can kick nasty voltage spikes onto the DC link, and a single electrolytic capacitor rarely fixes the problem. Jason Sachs uses simulations and practical PCB layout advice to show how a three-tier decoupling strategy — bulk electrolytic, mid-value ceramics or film, and many small HF bypass capacitors plus PCB plane capacitance — tames spikes, reduces EMI, and avoids harmful resonances when parts and vias are placed correctly.
Lost Secrets of the H-Bridge, Part V: Gate Drives for Dummies
Learn the most important issues in power MOSFET and IGBT gate drives: - Transistor behavior during switching - Calculating turn-on and turn-off times - Passive components used between gate drive IC and transistor - Reverse recovery - Capacitively-coupled spurious turn-on - Factors that influence a good choice of turn-on and turn-off times - Gate drive supply voltage management - Bootstrap gate drives - Design issues impacting reliability
Ten Little Algorithms, Part 1: Russian Peasant Multiplication
Jason Sachs revisits a centuries-old multiplication trick and shows why it still matters. He lays out Russian Peasant Multiplication with simple Python code, then reveals how the same shift-and-add pattern maps to GF(2) polynomial arithmetic and to exponentiation by squaring. The post mixes historical context with practical bitwise techniques that are useful for embedded and low-level math work.
PID Without a PhD
You do not need control theory to implement useful PID loops in embedded projects. Tim Wescott walks through simple, ready-to-use C code, clear explanations of P, I and D terms, and a practical tuning recipe you can apply to motors, precision actuators, and heaters. The article highlights anti-windup, sampling-rate guidance, and when to call in a control expert.
DSPRelated and EmbeddedRelated now on Facebook & I will be at EE Live!
Stephane Boucher announces two practical updates for DSPRelated readers. He launched Facebook pages for DSPRelated and EmbeddedRelated so members can get faster updates, and he will be attending EE Live in San Jose from March 30 to April 3 with a $100-off promo code for early registration. He also asks the community for ideas on how to make his conference coverage most useful.
Free Embedded Systems Books
Want a one-stop list of legally free embedded systems books online? Stephane Boucher launched a collaborative Google Docs experiment to crowdsource the best titles made available by authors and publishers, not pirates. Add missing entries, prune unsuitable links, and help build a curated, shareable collection of trusted embedded-reading material for firmware engineers and embedded Linux developers.
Collaborative Writing Experiment: What are your favorite Embedded Systems Online Resources?
Stephane Boucher invited the EmbeddedRelated community to co-create a live, crowd-sourced list of favorite embedded systems online resources using a Google Docs document. Readers could add links, vote by adding pluses, and watch edits appear in real time, while the author monitored for spam, planned moderation, and later closed the document after collecting contributions and trying to boost participation via Reddit/ece. It is a hands-on experiment in community curation.
Success Story
A single C programming article just set a new pageview record across the related sites, and the reason is pretty clear. Stephen Friederichs’s Data Hiding in C caught fire on Reddit, drew more than 7,000 readers, and even pushed a companion code snippet into the reward max. The post is also a quick look at how good technical writing can turn into real visibility and payment.
Code Snippets Winners Announced
Stephane Boucher announces the winners of EmbeddedRelated’s code snippet reward program after reviewing more than 50 submissions. The selected snippets include a software timer system, MSP430 SPI master IO without interrupts, base64 encoding, a debug print trace macro, and bit manipulation macros. It is also a reminder that submissions are still open, with cash rewards still available for approved snippets.
Now on Twitter + More Code Snippets Incentives
Stephane Boucher announces that EmbeddedRelated, DSPRelated, and FPGARelated are now on Twitter, with occasional timed giveaways for early visitors. He also highlights the new code snippets section, which has ten submissions and a rewards program: approved snippets can earn up to $50, and five standout March submissions will receive an extra $100 each. The post invites engineers to share useful embedded code.
New Code Snippet Section
Stephane Boucher launches a code snippet section on EmbeddedRelated, inviting embedded engineers to share short, useful code. Contributors get $10 for each approved submission via PayPal, plus performance bonuses: $10 when a snippet reaches 100 pageviews and $30 at 500 pageviews through 2013. It's an easy way to get credit and a small reward for reusable firmware and microcontroller code.
Two jobs
Stephane Boucher explains why EmbeddedRelated went quiet for a few months after a volunteer project demanded more of his time. He and his wife organized a clown-gymnastics show with 15 kids, sold more than 700 of 800 tickets, and raised $2,700 for the Tree of Hope. Now the shows are done and he plans to resume regular posting with new site features.
October winner announced
EmbeddedRelated is wrapping up another monthly draw for forum users who helped rate old threads and clean up the archives. For October, the new iPod Touch goes to hssathya, and Stephane Boucher also looks ahead to the next prize, an iPad mini, tied to ratings submitted in November and December. It is a simple incentive, but it keeps the forums tidier and the community engaged.
Behold, the New Comments System!
EmbeddedRelated has a new commenting system, and it is built to feel much smoother for readers. Stephane Boucher says it uses Ajax so comments post without reloading the page, and it now supports threaded replies for cleaner discussions. He also notes that guests can still comment, as long as they confirm their email address.
