Peripheral Interaction Without a Linux Device Driver Using Spidev
Overview
When integrating a new peripheral onto an embedded Linux platform, we might think we always need to implement a kernel module to serve as a device driver. However, as we all know, absolutes such as “always” and “never” are rarely true. The same is true in this case. Implementing a device driver in kernel space on an embedded Linux platform should only be undertaken if the performance requirements of the final application demand it. In most instances, a userspace...
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...
C to C++: 3 Reasons to Migrate
I’ve recently written several blogs that have set the stage with a simple premise: The C programming language no longer provides embedded software developers the tools they need to develop embedded software throughout the full software stack. Now, don’t get me wrong, C is a powerhouse, with over 80% of developers still using it; however, as embedded systems have reached unprecedented levels of complexity, C might not be the right tool for the job.
In this post, I’m kicking...
Favorite Software AND Hardware Tools for Embedded Systems Development
Last year, at the Embedded Online Conference, we interviewed the speakers and asked them what were some of their favorite software and hardware tools for Embedded development.
We aggregated all their answers in one insightful video that you can watch here.
Although you should really watch the video in order to get the full picture, I've compiled the following non-exhaustive list for the fun of it (again, I cannot overstate enough how much valuable...
Getting Started With Embedded Linux - From Nothing To A Login Prompt
One of the famous observations that have been made related to embedded systems is referred to as “Moore’s Law”, which states that the number of transistors in integrated circuits doubles every year. This observation has held mostly true for the past several decades, so powerful CPUs are no longer simply relegated to servers, desktops, and laptops. Instead, we see powerful CPUs with increased capabilities being introduced into embedded systems on devices that live at “the edge”....
A New Related Site!
We are delighted to announce the launch of the very first new Related site in 15 years! The new site will be dedicated to the trendy and quickly growing field of Machine Learning and will be called - drum roll please - MLRelated.com.
We think MLRelated fits perfectly well within the “Related” family, with:
- the fast growth of TinyML, which is a topic of great interest to the EmbeddedRelated community
- the use of Machine/Deep Learning in Signal Processing applications, which is of...
Five ‘80s Movies that Inspired Me to Become an Engineer
Five ‘80s Movies that Inspired Me to Become an Engineer
Movies and pop culture can incredibly impact society, particularly children. However, we never really know what conversation, demonstration, or movie could inspire someone to become an engineer. Recently in the Beningo house, we ran out of the film to watch for movie night. In desperation, I decided to find great movies from my childhood in the 80s. To my surprise, I realized how influential several of these films inspired me to...
3 Overlooked Embedded Software Elements
Have you ever wondered, while you and your team are busy writing software if the foundation of how embedded software systems are built has changed and left you in the dust? What if while you were busily focusing on getting your product out the door, fighting bugs, and dealing with supply issues, there were techniques and processes that you completely overlooked that could save the day? I’ve found three elements embedded software teams often underutilize that could dramatically improve...
Getting Started With Zephyr: Saving Data To Files
In this blog post, I show how to implement a Zephyr application to mount a microSD card, create a new file on the microSD card, and write data to it. The lessons learned from such an application can be helpful for devices out in the field that need to write data to off-board memory periodically, especially in cases where Internet access may be sporadic.
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...
Using the C language to program the am335x PRU
Introduction
Some weeks ago, I published an article on how we used the PRU to implement a power supply control loop having hard realtime constraints:
//www.embeddedrelated.com/showarticle/586.php
Writing this kind of logic in assembly language is not easy. First the assembly language itself may be difficult to learn depending on your background. Then, fixed and floating point arithmetics require lot of code. While macros help to handle the complexity, they still are error prone as you...
Which MOSFET topology?
A recent electronics.StackExchange question brings up a good topic for discussion. Let's say you have a power supply and a 2-wire load you want to be able to switch on and off from the power supply using a MOSFET. How do you choose which circuit topology to choose? You basically have four options, shown below:
From left to right, these are:
High-side switch, N-channel MOSFET High-side switch, P-channel MOSFET Low-side switch, N-channel...Data Types for Control & DSP
There's a lot of information out there on what data types to use for digital signal processing, but there's also a lot of confusion, so the topic bears repeating.
I recently posted an entry on PID control. In that article I glossed over the data types used by showing "double" in all of my example code. Numerically, this should work for most control problems, but it can be an extravagant use of processor resources. There ought to be a better way to determine what precision you need...
Launch of EmbeddedRelated.tv
With the upcoming Embedded Word just around the corner, I am very excited to launch the EmbeddedRelated.tv platform.
This is where you will find the schedule for all the live broadcasts that I will be doing from Embedded World next week. Please note that the schedule will be evolving constantly, even during the show, so I suggest your refresh the page often. For instance, I am still unsure if I will be able to do the 'opening of the doors' broadcast as...
10 Circuit Components You Should Know
Chefs have their miscellaneous ingredients, like condensed milk, cream of tartar, and xanthan gum. As engineers, we too have quite our pick of circuits, and a good circuit designer should know what's out there. Not just the bread and butter ingredients like resistors, capacitors, op-amps, and comparators, but the miscellaneous "gadget" components as well.
Here are ten circuit components you may not have heard of, but which are occasionally quite useful.
1. Multifunction gate (
Linear Feedback Shift Registers for the Uninitiated, Part XVI: Reed-Solomon Error Correction
Last time, we talked about error correction and detection, covering some basics like Hamming distance, CRCs, and Hamming codes. If you are new to this topic, I would strongly suggest going back to read that article before this one.
This time we are going to cover Reed-Solomon codes. (I had meant to cover this topic in Part XV, but the article was getting to be too long, so I’ve split it roughly in half.) These are one of the workhorses of error-correction, and they are used in...
Peripheral Interaction Without a Linux Device Driver Using Spidev
OverviewWhen integrating a new peripheral onto an embedded Linux platform, we might think we always need to implement a kernel module to serve as a device driver. However, as we all know, absolutes such as “always” and “never” are rarely true. The same is true in this case. Implementing a device driver in kernel space on an embedded Linux platform should only be undertaken if the performance requirements of the final application demand it. In most instances, a userspace...
Live Streaming from Embedded World!
For those of you who won't be attending Embedded World this year, I will try to be your eyes and ears by video streaming live from the show floor.
I am not talking improvised streaming from a phone, but real, high quality HD streaming with a high-end camera and a device that will bond three internet connections (one wifi and two cellular) to ensure a steady, and hopefully reliable, stream. All this to hopefully give those of you who cannot be there in person a virtual...
Discrete-Time PLLs, Part 1: Basics
In this series of tutorials on discrete-time PLLs we will be focusing on Phase-Locked Loops that can be implemented in discrete-time signal proessors such as FPGAs, DSPs and of course, MATLAB.
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...
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...
VGA Output in 7 Slices. Really.
Ridiculous? Read on - I will show you how to generate VGA timing in seven XilinxR Spartan3R slices.Some time ago I needed to output video to a VGA monitor for my Apple ][ FPGA clone. Obviously (I thought), VGA's been done before and all I had to do was find some Verilog code and drop it into my design. As is often the case (with me anyway), the task proved to be very different from my imagined 'couple of hours to integrate the IP'.I found some example code for my board. I...
How to use I2C devices in (Apache) NuttX: Adding support for an I2C device in your board
Previously in this EmbeddedRelated article, we saw how to find an I2C device connected to your board using the i2ctool that is very familiar for people with previous experience with embedded Linux. Today we will see how to add support to an I2C device (i.e. BMP280 sensor) in your board. So, lets to get started!
NuttX uses a very simple approach to interface with devices connected to the board: each board has a board bringup() function that is used to initialize the...
Practical CRCs for Embedded Systems
CRCs are a very practical tool for embedded systems: you're likely to need to use one as part of a communications protocol or to verify the integrity of a program image before writing it to flash. But CRCs can be difficult to understand and tricky to implement. The first time I attempted to write CRC code from scratch I failed once. Then twice. Then three times. Eventually I gave up and used an existing library. I consider myself intelligent: I got A's...
Favorite Tools: C++11 std::array
Many embedded software and firmware projects must be developed to high standards of reliability. To meet these reliability requirements, firmware project teams will consider many design tradeoffs. For example, an engineering team may avoid or outright ban the use of dynamic memory allocation, a feature typically accessed via the C library call "malloc" or the C++ allocator "new". When authoring software under such...
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...
10 Items of Test Equipment You Should Know
When life gets rough and a circuit board is letting you down, it’s time to turn to test equipment. The obvious ones are multimeters and oscilloscopes and power supplies. But you know about those already, right?
Here are some you may not have heard of:
Non-contact current sensors. Oscilloscope probes measure voltage. When you need to measure current, you need a different approach. Especially at high voltages, where maintaining galvanic isolation is important for safety. The usual...
Homebrew CPUs: Messing around with a J1
In this article I will examine James Bowman's excellent J1 CPU; I will then proceed to mess around with various parts of it, making it smaller, more appropriate to my particular application, and possibly faster. I hope this will show you how easy it is to fiddle around with homemade CPUs and encourage you to make something weird and wonderful.
J1 CPUMy hat is off to James Bowman. J1 is pretty cool. It is a stack machine; it executes instructions in one cycle, it is...
