Linear Feedback Shift Registers for the Uninitiated, Part I: Ex-Pralite Monks and Finite Fields
Later there will be, I hope, some people who will find it to their advantage to decipher all this mess.
— Évariste Galois, May 29, 1832
I was going to call this short series of articles “LFSRs for Dummies”, but thought better of it. What is a linear feedback shift register? If you want the short answer, the Wikipedia article is a decent introduction. But these articles are aimed at those of you who want a little bit deeper mathematical...
Tenderfoot: Recommended Reading
Twenty years ago I read Code Complete by Steve McConnell. And then read it again. And again. And again. Of all the books I have read during my career, I believe this was the book that catapulted me from a young electrical engineer to a young and aspiring embedded software engineer. So to all the ‘tenderfoots’ embarking upon an embedded systems and especially embedded software and firmware career, this entry is for you.
First, I would certainly recommend that all engineers read and read...
Embedded Toolbox: Programmer's Calculator
Like any craftsman, I have accumulated quite a few tools during my embedded software development career. Some of them proved to me more useful than others. And these generally useful tools ended up in my Embedded Toolbox. In this blog, I'd like to share some of my tools with you. Today, I'd like to start with my cross-platform Programmer's Calculator called QCalc.
I'm sure that you already have your favorite calculator online or on your smartphone. But can your calculator accept...
VERY Fast Japanese Sumo Robots
For some reasons, I could not stop watching. I would love to have the maker of one of these robots to blog about the project here on EmbeddedRelated.com, the sensors, microcontroller, algorithms and the challenges... This would make for a very interesting read! Do you know someone?
Ten Little Algorithms, Part 6: Green’s Theorem and Swept-Area Detection
Other articles in this series:
- Part 1: Russian Peasant Multiplication
- Part 2: The Single-Pole Low-Pass Filter
- Part 3: Welford's Method (And Friends)
- Part 4: Topological Sort
- Part 5: Quadratic Extremum Interpolation and Chandrupatla's Method
This article is mainly an excuse to scribble down some cryptic-looking mathematics — Don’t panic! Close your eyes and scroll down if you feel nauseous — and...
Going back to Germany!
A couple of blog posts ago, I wrote that the decision to go to ESC Boston ended up being a great one for many different reasons. I came back from the conference energized and really happy that I went.
These feelings were amplified a few days after my return when I received an email from Rolf Segger, the founder of SEGGER Microcontroller (check out their very new website), asking if I would be interested in visiting their headquarters...
ESC Boston's Videos are Now Up
In my last blog, I told you about my experience at ESC Boston and the few videos that I was planning to produce and publish. Here they are, please have a look and any feedback (positive or negative) is appreciated.
Short HighlightThis is a very short (one minute) montage of some of the footage that I shot at the show & conference. In future shows, I absolutely need to insert clips here and there of engineers saying a few words about the conference (why they...
How to Give Persistent Names To USB-Serial Devices on Ubuntu 14.04
If you have a bunch of USB-serial devices connected to your dock station and you needed to bind your USB-serial devices under static names so that all the USB-serial devices don't get to be assigned to random names by "udev" manager when you re-plug your laptop to the dock station, follow the instructions below. I will share the udev rules I created as a reference and give the step by step instructions to achieve persistent naming. All the steps worked on my Ubuntu 14.04...
Tenderfoot: Introduction to Magic (Numbers that is...)
Once upon a time, while participating in a source code review, I stumbled across the following C code in a header file:
struct Foo { //various structure fields char string_buffer[45+3]; //buffer requires about 45 bytes };My right eyebrow raised, I took a note, and continued with the code review, only to later stumble into this line of code in the body of a C function:
char * temp_string_buffer = (char*) malloc(45+3);Again, I took a note on this function, and continued...
Back from ESC Boston
NOT going to ESC Boston would have allowed me to stay home, in my comfort zone.
NOT going to ESC Boston would have saved me from driving in the absolutely horrible & stressful Boston traffic1.
NOT going to ESC Boston would have saved me from having to go through a full search & questioning session at the Canada Customs on my return2.
2017/06/06 update: Videos are now up!So two days...
Finally got a drone!
As a reader of my blog, you already know that I have been making videos lately and thoroughly enjoying the process. When I was in Germany early this summer (and went 280 km/h in a porsche!) to produce SEGGER's 25th anniversary video, the company bought a drone so we could get an aerial shot of the party (at about the 1:35 mark in this video). Since then, I have been obsessing on buying a drone for myself and finally made the move a few weeks ago - I acquired a used DJI...
Linear Feedback Shift Registers for the Uninitiated, Part VII: LFSR Implementations, Idiomatic C, and Compiler Explorer
The last four articles were on algorithms used to compute with finite fields and shift registers:
- multiplicative inverse
- discrete logarithm
- determining characteristic polynomial from the LFSR output
Today we’re going to come back down to earth and show how to implement LFSR updates on a microcontroller. We’ll also talk a little bit about something called “idiomatic C” and a neat online tool for experimenting with the C compiler.
The Least Interesting Circuit in the World
It does nothing, most of the time.
It cannot compute pi. It won’t oscillate. It doesn’t light up.
Often it makes other circuits stop working.
It is… the least interesting circuit in the world.
What is it?
About 25 years ago, I took a digital computer architecture course, and we were each given use of an ugly briefcase containing a bunch of solderless breadboards and a power supply and switches and LEDs — and a bunch of
StrangeCPU #1. A new CPU
Summary: In this multi-part series I will share with you a design, implementation notes and code for a slightly different kind of a CPU featuring a novel token machine that resolves an 8-bit token to pretty much any address in a 32-bit or even 64-bit address space, using not much more than an adder.
Table of Contents:- Part 1: A new CPU - technology review, re-examination of the premises; StrangeCPU concepts; x86 notes.
Signal Processing Contest in Python (PREVIEW): The Worst Encoder in the World
When I posted an article on estimating velocity from a position encoder, I got a number of responses. A few of them were of the form "Well, it's an interesting article, but at slow speeds why can't you just take the time between the encoder edges, and then...." My point was that there are lots of people out there which take this approach, and don't take into account that the time between encoder edges varies due to manufacturing errors in the encoder. For some reason this is a hard concept...
Embedded Systems - free EdX course by UT-Austin!
I was very excited to see that there will be an Embedded Systems class available for free at https://www.edx.org/course/utaustin/ut-6-01x/embedded-systems-shape-world/1172
It's free to sign up and take the online class at the EdX website.
More exciting is that the class is based on a TI Launchpad Tiva microcontroller development board. The Tiva Launchpad features an 80-MHz ARM Cortex M-4 MCU with 256 KB of flash storage, 32 KB of RAM and 43 general purpose I/O pins.
DSPRelated and EmbeddedRelated now on Facebook & I will be at EE Live!
I have two news to share with you today.
The first one is that I finally created Facebook pages for DSPRelated.com and EmbeddedRelated (DSPRelated page - EmbeddedRelated page). For a long time I didn't feel that this was something that was needed, but it seems that these days more and more people are using their Facebook account to stay updated with their favorite websites. In any event, if you have a Facebook account, I would greatly appreciate if you could use the next 5 seconds to "like"...
Get Involved: Contribute Quiz Questions for the Embedded Systems Community for a Chance to Win a LAP-C Pro!
Submit a Quiz Question for a chance to win a Zeroplus Lac-C Pro!
Another 10 Circuit Components You Should Know
It's that time again to review all the oddball goodies available in electronic components. These are things you should have in your bag of tricks when you need to design a circuit board. If you read my previous posts and were looking forward to more, this article's for you!
1. Bus switches
I can't believe I haven't mentioned bus switches before. What is a bus switch?
There are lots of different options for switches:
- mechanical switch / relay: All purpose, two...
Arduino robotics #2 - chassis, locomotion and power
Arduino RoboticsBeginner robotics is a series of article chronicling my first autonomous robot build, Clusterbot. This build is meant to be affordable, relatively easy and instructive. The total cost of the build is around $50.
1. Arduino robotics - motor control2. Arduino robotics - chassis, locomotion and power3. Arduino robotics - wiring, coding and a test run4.Supply Chain Games: What Have We Learned From the Great Semiconductor Shortage of 2021? (Part 1)
So by now I’m sure you’ve heard about the semiconductor shortage of 2021. For a few complicated reasons, demand is greater than supply, and not everybody who wants to buy integrated circuits can do so. Today we’re going to try to answer some hard questions:
- Why are we in the middle of a semiconductor shortage?
- Why is it taking so long to get my [insert part number here]?
- Did this shortage suddenly sneak up on everybody? If not, what were the signs, and why...
Free Sessions @ the 2023 Embedded Online Conference
Although the 2023 Embedded Online Conference will officially start only on Monday 04/24, today we are pre-releasing all Theatre Talks and Demos in order to give attendees a headstart over the weekend on a very busy program.
The good news is, you don't need a paid registration to access theatre talks and demos. All you have to do is create an account on the EOC website and skip the payment part.
Here are the 37 sessions that you can watch for...
Dark Corners of C - The Comma Operator
I've been programming in C for 16 years or so and the language has existed for much much longer than that. You might think that there'd be nothing left to surprise me after so long - but you'd be wrong. Imagine my surprise the first time I saw a line of code that looked something like this:
if (!dry_run && ((stdout_closed = true), close_stream (stdout) != 0))My mind couldn't parse it - what's a comma doing in there (after...
Helping New Bloggers to Break the Ice: A New Ipad Pro for the Author with the Best Article!
Breaking the ice can be tough. Over the years, many individuals have asked to be given access to the blogging interface only to never post an article.
Hot Fun in the Silicon: Thermal Testing with Power Semiconductors
Here's a trick that is useful the next time you do thermal testing with your MOSFETs or IGBTs.
Thermal testing?!
Yes, that's right. It's important to make sure your power transistors don't overheat. In the datasheet, you will find some information that you can use to estimate how hot the junction inside the IC will get.
Let's look at an example. Here's a page from the IRF7739 DirectFET datasheet. I like this datasheet because it has almost all the thermal stuff on one page,...
Getting Started With Zephyr: Writing Data to EEPROM
In this blog post, I show how to implement a Zephyr application to interact with EEPROM. I show how the Zephyr device driver model allows application writers to be free of the underlying implementation details. Unfortunately, the application didn't work as expected, and I'm still troubleshooting the cause.
8 Weeks - 8 Giveaways!
If for some reason, you've been putting off registering for the upcoming 2021 Embedded Online Conference, here are 8 good reasons to register today.
The idea is simple; if you are registered for the conference by the 'raffle date' for any of the following giveaways, you'll automatically be entered into the draw.
So for instance, if you are already registered for the conference or register before March the 22nd, you'll be automatically entered into the 8 draws...
Mathematics and Cryptography
The mathematics of number theory and elliptic curves can take a life time to learn because they are very deep subjects. As engineers we don't have time to earn PhD's in math along with all the things we have to learn just to make communications systems work. However, a little learning can go a long way to helping make our communications systems secure - we don't need to know everything. The following articles are broken down into two realms, number theory and elliptic...
Introducing the VPCIe framework
Introduction
My daily work involves platforms featuring an embedded CPU communcating with a FPGA device over a PCI Express link (PCIe for short). The main purpose of this link is for the CPU to convey configuration, control, and status commands to hardware slaves implemented in the FPGA. For data intensive applications (2D XRay detector readout backend), this link can also be used as a DMA channel to transfer data from the FPGA to the CPU memory. Finally, a slave can interrupt the CPU using...
Racing to Sleep
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...
