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...
Donald Knuth Is the Root of All Premature Optimization
This article is about something profound that a brilliant young professor at Stanford wrote nearly 45 years ago, and now we’re all stuck with it.
TL;DRThe idea, basically, is that even though optimization of computer software to execute faster is a noble goal, with tangible benefits, this costs time and effort up front, and therefore the decision to do so should not be made on whims and intuition, but instead should be made after some kind of analysis to show that it has net...
Launch of Youtube Channel: My First Videos - Embedded World 2017
I went to Embedded World 2017 in Nuremberg with an ambitious plan; I would make video highlights of several exhibits (booths) to be presented to the *Related sites audience. I would try to make the vendors focus their pitch on the essential in order to produce a one to three minutes video per booth.
So far my experience with making videos was limited to family videos, so I knew I had lots of reading to do and lots of Youtube videos and tutorials to watch. Trade shows are...
Introduction to Microcontrollers - More On Interrupts
A Little More Detail About The Interrupt Mechanism
It's time to look a little closer at what happens in an interrupt request and response. Again this is in general terms, and different microcontroller designs may do things somewhat differently, but the basics remain the same. Most but not all interrupt requests are latched, which means the interrupt event sets a flag that stays set even if the interrupt event then goes away. It is this latched flag...
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...
Introduction to Microcontrollers - Buttons and Bouncing
What Is A Button?To your hardware, that is. As discussed in Introduction to Microcontrollers - More On GPIO, a button (or key, or switch, or any form of mechanical contact) is generally hooked up to a microcontroller so as to generate a certain logic level when pushed or closed or "active," and the opposite logic level when unpushed or open or "inactive." The active logic level can be either '0' or '1', but for reasons both historical and electrical, an...
Unit Tests for Embedded Code
I originate from an electrical engineering background and my first industry experience was in a large, staid defense contractor. Both of these experiences contributed to a significant lack of knowledge with regards to software development best practices. Electrical engineers often have a backwards view of software in general; large defense contractors have similar views of software and couple it with a general disdain for any sort of automation or ‘immature’ practices. While there...
How to use SPI devices in NuttX RTOS
Previously in this EmbeddedRelated article, we saw how to use I2C device connected to your board. Although I2C devices are very common nowadays, probably you will need to use some SPI device as well. Today we will see how to do exactly that. So, lets to get started!
The SPI (Serial Peripheral Interface) is synchronous serial communication protocol (by synchronous it means there is a common clock signal to indicate when which signal transition will occur)....
UML Statechart tip: Handling errors when entering a state
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...
StrangeCPU #3. Instruction Slides - The Strangest CPU Yet!
Summary:
Decoding instructions with a Sliding Window system. 0-Bit Sliding Register Windows.
Table of Contents:- Part 1: A new CPU - technology review, re-examination of the premises; StrangeCPU concepts; x86 notes.
- Part 2: Sliding-Window Token Machines, an in-depth exploration of this curious technology; ARM notes.
- Part 3. Instruction Slides - The Strangest CPU Yet! Decoding instructions with a Sliding...
You Don't Need an RTOS (Part 3)
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.
Watchdog Timer Anti-patterns
The humble watchdog timer has been an essential part of our reliability tool chest for decades now. The way it works is straightforward and easy to understand, and most practical designs are easy to interface with.
There is a wealth of reference material that covers both the theory behind watchdog timers and practical design tips. But what we'll talk about today is of a slightly different nature.
Despite its straightforward operation and long history, the watchdog timer does occasionally get...
Getting Started with the Microchip PIC® Microcontroller
This first post of a five part series looks at the available hardware options for getting started with Microchip 8-bit PIC® Microcontroller, explores the MPLAB® X Integrated Development Environment and walks through setting up a project to expose the configured clock to an external pin and implement a single output GPIO to light an LED.
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,...
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...
Getting Started with NuttX RTOS on Three Low Cost Boards
If you are an embedded system developer chances are you already played with Linux on some embedded board and saw how it is powerful, right?
So, I have a good news: you can have same power using NuttX on some ultra low cost board powered by a microcontroller instead of microprocessor (that normally is way more expansive).
In fact many companies already realized it before me. It explains why NuttX is the kernel used by many IoT frameworks:
Another great news is that few days ago...
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.
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.
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...
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.
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...
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...
