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Scorchers, Part 2: Unknown Bugs and Popcorn

Jason Sachs April 5, 20203 comments

This is a short article about diminishing returns in the context of software releases.

Those of you who have been working professionally on software or firmware have probably faced this dilemma before. The scrum masters of the world will probably harp on terms like the Definition of Done and the Minimum Viable Product. Blah blah blah. In simple terms, how do you know when your product is ready to release? This is both an easy and a difficult question to answer.

What makes...


Some Advice For Working From Home

Steve Branam March 28, 20201 comment

The other day I posted a short video of my WFH setup (and here's a May 1st upgrade). Today I have some general advice for WFH for people who are new to it.

I've been doing it randomly for the past 5 years, usually just one or two days a week here and there. Now it's a full-time thing for the duration of the coronavirus. So some of this wanders afield a bit, settling in for the long haul.

Some of it is based on things I've built up over years. It's unreasonable to expect that...


UML Statechart tip: Handling errors when entering a state

Matthew Eshleman March 8, 20204 comments

This is my second post with advice and tips on designing software with UML statecharts. My first entry is here.

It has been nearly 20 years since I first studied UML statecharts. Since that initial exposure (thank you Samek!), I have applied event driven active object statechart designs to numerous projects [3]. Nothing has abated my preference for this pattern in my firmware and embedded software projects. Through the years I have taken note of a handful of common challenges when...


Examining The Stack For Fun And Profit

Steve Branam February 19, 20201 comment

Well, maybe not so much for profit, but certainly for fun. This is a wandering journey of exploration and discovery, learning a variety of interesting and useful things.

One of the concerns with an embedded system is how much memory it needs, known as the memory footprint. This consists of the persistent storage needed for the program (i.e. the flash memory or filesystem space that stores the executable image), and the volatile storage needed to hold the data while executing over long...


Already 3000+ Attendees Registered for the Upcoming Embedded Online Conference

Stephane Boucher February 14, 2020

Chances are you already know, through the newsletter or banners on the Related sites, about the upcoming Embedded Online Conference.

Chances are you also already know that you have until the end of the month of February to register for free. 

And chances are that you are one of the more than 3000 pro-active engineers who have already registered.

But If you are like me and have a tendency to do tomorrow what can be done today, maybe you haven't registered yet.  You may...


Racing to Sleep

Jason Sachs December 30, 2019

Today we’re going to talk about low-power design.

Suppose I’m an electrical engineer working with wildlife biologists who are gathering field data on the Saskatchewan ringed-neck mountain goat. My team has designed a device called the BigBrotherBear 2000 (BBB2000) with a trip cable and a motor and a camera and a temperature sensor and a hot-wire anemometer and a real-time clock and an SD card and a battery and a LoRa transceiver. The idea is something like...


Jaywalking Around the Compiler

Jason Sachs December 9, 20193 comments

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?


Shibboleths: The Perils of Voiceless Sibilant Fricatives, Idiot Lights, and Other Binary-Outcome Tests

Jason Sachs September 29, 2019

AS-SALT, JORDAN — Dr. Reza Al-Faisal once had a job offer from Google to work on cutting-edge voice recognition projects. He turned it down. The 37-year-old Stanford-trained professor of engineering at Al-Balqa’ Applied University now leads a small cadre of graduate students in a government-sponsored program to keep Jordanian society secure from what has now become an overwhelming influx of refugees from the Palestinian-controlled West Bank. “Sometimes they visit relatives...


Embedded Programming Video Course Shows How OOP Works Under the Hood

Miro Samek September 29, 2019

If you'd like to understand how Object-Oriented Programming (OOP) really works under the hood, here is a free video course for you:

OOP part-1: Encapsulation: This first lesson on Object-Oriented Programming (OOP) introduces the concept of Encapsulation, which is the ability to package data and functions together into classes. You'll see how you can emulate Encapsulation in C, what kind of code is generated, and how to debug such code. Next, you will translate the C design into C++ using...


Levitating Globe Teardown, Part 2

Tim Wescott November 6, 20139 comments

Part 1 of this article was really more of an extended (and cynical) product review.  In this part of the article, I actually take things apart (sometimes a bit more suddenly than I meant to) and show you some innards.First the globe.  I knew there was a magnet in there someplace, because it's obviously plastic and it also attracts metal.  I had intended to gently part the globe at the glue bond along the equator.  I started by trying to gently flex the thing on my work...


Tolerance Analysis

Jason Sachs May 31, 2020

Today we’re going to talk about tolerance analysis. This is a topic that I have danced around in several previous articles, but never really touched upon in its own right. The closest I’ve come is Margin Call, where I discussed several different techniques of determining design margin, and ran through some calculations to justify that it was safe to allow a certain amount of current through an IRFP260N MOSFET.

Tolerance analysis...


The Other Kind of Bypass Capacitor

Jason Sachs January 3, 20173 comments

There’s a type of bypass capacitor I’d like to talk about today.

It’s not the usual power supply bypass capacitor, aka decoupling capacitor, which is used to provide local charge storage to an integrated circuit, so that the high-frequency supply currents to the IC can bypass (hence the name) all the series resistance and inductance from the power supply. This reduces the noise on a DC voltage supply. I’ve...


How to make a heap profiler

Yossi Kreinin May 23, 20141 comment

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...

Stairway to Thévenin

Jason Sachs December 31, 2011

This article was inspired by a recent post on reddit asking for help on Thévenin and Norton equivalent circuits.

(With apologies to Mr. Thévenin, the rest of the e's that follow will remain unaccented.)

I still remember my introductory circuits class on the subject, roughly as follows:

(NOTE: Do not get scared of what you see in the rest of this section. We're going to point out the traditional approach for teaching linear equivalent circuits first. If you have...


Jaywalking Around the Compiler

Jason Sachs December 9, 20193 comments

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?


Metal detection: beat frequency oscillator

Fabien Le Mentec January 30, 20161 comment
Plan Introduction Theory Electronics Software Tests ReferencesNext part: building the detector 1. Introduction

This article discusses the implementation of a beat frequency oscillator (BFO) stage for metal detector. While they are mentioned here and there, the article does not detail other important electronic stages such as the power supply, and user interface, the coil or the detector frame. I may write other articles on these topics, and other detection methods.Before...


Little to no benefit from C based HLS

Christopher Felton April 4, 2014

Last updated 07-Nov-2015

As I write this I am on a plane and my destination is EELive 2014 where I am going to give a talk hardware design: the grunge era.  It is a shotgun introduction to three alternative hardware description languages (alt.hdl). The three languages briefly introduced in the talk are: bsv, chisel, and myhdl.  The goal of the talk is simply to raise awareness of the three...


A wireless door monitor based on the BANO framework

Fabien Le Mentec June 10, 20145 comments
Introduction

I have been thinking for a while about a system to monitor the states of my flat and my garage doors from a remote place. Functionnaly, I wanted to monitor the state of my doors from a remote place. A typical situation is when I leave for holidays, but it can also be useful from the work office. To do so, I would centralize the information on a server connected on the Internet that I could query using a web browser. The server itself would be located in the appartement, where...


The 2024 Embedded Online Conference