
Finite State Machines (FSM) in Embedded Systems (Part 2) - Simple C++ State Machine Engine
When implementing state machines in your project it is an advantage to rely on a tried and tested state machine engine. This component is reused for every kind of application and helps the developer focus on the domain part of the software. In this article, the design process that turns a custom C++ code into a finite-state machine engine is fully described with motivations and tradeoffs for each iteration.
Getting Started With CUDA C on an Nvidia Jetson: Hello CUDA World!
In this blog post, I introduce CUDA, which is a framework designed to allow developers to take advantage of Nvidia's GPU hardware acceleration to efficiently implement certain type of applications. I demonstrate an implementation to perform vector addition using CUDA C and compare it against the traditional implementation in "regular" C.
Modeling Gate Drive Diodes
This is a short article about how to analyze the diode in some gate drive circuits when figuring out turn-off characteristics --- specifically, determining the relationship between gate drive current and gate voltage during turn-off of a power transistor.
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.
Make Your Own MCU Boards (2023 Teardown Conference)
Ditch the development boards! Products like the Nucleo development boards serve a wonderful purpose, but they’re ill-suited for projects that need to be small and cheap, such as hobby projects or products just beginning a production run. In this talk (a recording from the 2023 Teardown Conference), you’ll learn how to put a microcontroller or other custom circuit on a PCB a little larger than a stick of gum for less than $3 a board.
BusyBox; The Swiss Army Knife of Embedded Linux
In this article we cover the BusyBox, how it's designed to be optimized for embedded targets, and how to configure and build it in different ways, we also covered the license and limitation, which led to the development of ToyBox, I hope you enjoyed the article, please leave a comment for any correction or suggestions.
Creating a GPIO HAL and Driver in C
Creating a GPIO Hardware Abstraction Layer (HAL) in C allows for flexible microcontroller interfacing, overcoming the challenge of variability across silicon vendors. This method involves reviewing datasheets, identifying features, designing interfaces, and iterative development, as detailed in the "Reusable Firmware" process. A simplified approach prioritizes essential functions like initialization and read/write operations, showcased through a minimal interface example. The post also highlights the use of AI to expedite HAL generation. A detailed GPIO HAL version is provided, featuring extended capabilities and facilitating driver connection through direct assignments or wrappers. The significance of a configuration table for adaptable peripheral setup is emphasized. Ultimately, the blog illustrates the ease and scalability of developing a GPIO HAL and driver in C, promoting hardware-independent and extensible code for various interfaces, such as SPI, I2C, PWM, and timers, underscoring the abstraction benefits.
Using (Apache) NuttX USERLED Subsystem
In the previous article (https://embeddedrelated.com/showarticle/1623.php) we saw how to use GPIOs on NuttX testing on RaspberryPi Pico as example. In that article we used the GPIO output to control an LED, but there is a better way to do that. Of course, NuttX has an LED subsystem similar to Linux LED subsystem: it is called USERLED. Today we will see how to control LEDs using NuttX's USERLED subsystem.
The main advantage of using the USERLED...
3D printing for embedded development
Used mostly for creating little plastic objects, the desktop 3D printer is not an obvious addition to the embedded developer's toolbox. However, if you're looking for more reasons to get one, or already have one that's mostly gathering dust, here are a couple of embedded-related ways to get more value out of it.
Sheep Bridge: In Praise of Generalists and System Engineers
Today I want to talk about generalists and system engineers: why they’re important and why they’re different from each other.
Specialists and GeneralistsA specialist is someone who has a very deep understanding of a particular subject, and spends much of the time working on aspects of that subject. Few others are capable of doing the specialist’s work. I recently wrote an article on gate drive design (Lost Secrets of the H-Bridge,...
VHDL tutorial - A practical example - part 1 - Hardware
In previous posts I described some simple VHDL examples. This time let's try something a little more complex. This is part one of a multiple part article. This is intended to be a detailed description of one of several initial designs that I developed for a client. This design never made it into a product, but a similar design was used and is currently being produced. As a considerable amount of work was put into this effort, I decided to share this design...
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…
C to C++: Using Abstract Interfaces to Create Hardware Abstraction Layers (HAL)
In C to C++, we've been exploring how to transition from a C developer to a C++ developer when working in embedded system. In this post, we will explore how to leverage classes to create hardware abstraction layers (HAL). You'll learn about the various inheritance mechanisms, what an virtual function is, and how to create an abstract class.
Introduction to Microcontrollers - Driving WS2812 RGB LEDs
This tutorial chapter is a bit of a detour, but I think an interesting and useful one. It introduces a bit of assembly language programming, and demonstrates bit-banging a tight serial data protocol. And it deals with RGB LEDs, which are just very fun in their own right, especially these new parts. So I thought I'd post this to give readers time for some holiday lighting experimenting.
Back To The FutureRemember how we started this...
VHDL tutorial - combining clocked and sequential logic
In an earlier article on VHDL programming ("VHDL tutorial" and "VHDL tutorial - part 2 - Testbench", I described a design for providing a programmable clock divider for a ADC sequencer. In this example, I showed how to generate a clock signal (ADCClk), that was to be programmable over a series of fixed rates (20MHz, 10MHz, 4MHz, 2MHz, 1MHz and 400KHz), given a master clock rate of 40MHz. A reader of that article had written to ask if it was possible to extend the design to...
Getting Started With Zephyr: Kconfig
In this blog post, we briefly look at Kconfig, one of the core pieces of the Zephyr infrastructure. Kconfig allows embedded software developers to turn specific subsystems on or off within Zephyr efficiently and control their behavior. We also learn how we can practically use Kconfig to control the features of our application using the two most common mechanisms.
Round Round Get Around: Why Fixed-Point Right-Shifts Are Just Fine
Today’s topic is rounding in embedded systems, or more specifically, why you don’t need to worry about it in many cases.
One of the issues faced in computer arithmetic is that exact arithmetic requires an ever-increasing bit length to avoid overflow. Adding or subtracting two 16-bit integers produces a 17-bit result; multiplying two 16-bit integers produces a 32-bit result. In fixed-point arithmetic we typically multiply and shift right; for example, if we wanted to multiply some...
How to Estimate Encoder Velocity Without Making Stupid Mistakes: Part II (Tracking Loops and PLLs)
Yeeehah! Finally we're ready to tackle some more clever ways to figure out the velocity of a position encoder. In part I, we looked at the basics of velocity estimation. Then in my last article, I talked a little about what's necessary to evaluate different kinds of algorithms. Now it's time to start describing them. We'll cover tracking loops and phase-locked loops in this article, and Luenberger observers in part III.
But first we need a moderately simple, but interesting, example...
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...
PID Without a PhD
I both consult and teach in the area of digital control. Through both of these efforts, I have found that while there certainly are control problems that require all the expertise I can bring to bear, there are a great number of control problems that can be solved with the most basic knowledge of simple controllers, without resort to any formal control theory at all.
This article will tell you how to implement a simple controller in software and how to tune it without getting into heavy...
How to Build a Fixed-Point PI Controller That Just Works: Part II
In Part I we talked about some of the issues around discrete-time proportional-integral (PI) controllers:
- various forms and whether to use the canonical form for z-transforms (don't do it!)
- order of operation in the integral term: whether to scale and then integrate (my recommendation), or integrate and then scale.
- saturation and anti-windup
In this part we'll talk about the issues surrounding fixed-point implementations of PI controllers. First let's recap the conceptual structure...
Round Round Get Around: Why Fixed-Point Right-Shifts Are Just Fine
Today’s topic is rounding in embedded systems, or more specifically, why you don’t need to worry about it in many cases.
One of the issues faced in computer arithmetic is that exact arithmetic requires an ever-increasing bit length to avoid overflow. Adding or subtracting two 16-bit integers produces a 17-bit result; multiplying two 16-bit integers produces a 32-bit result. In fixed-point arithmetic we typically multiply and shift right; for example, if we wanted to multiply some...
From Baremetal to RTOS: A review of scheduling techniques
Transitioning from bare-metal embedded software development to a real-time operating system (RTOS) can be a difficult endeavor. Many developers struggle with the question of whether they should use an RTOS or simply use a bare-metal scheduler. One of the goals of this series is to walk developers through the transition and decision making process of abandoning bare-metal thinking and getting up to speed quickly with RTOSes. Before diving into the details of RTOSes, the appropriate first step...
Introduction to Microcontrollers - Button Matrix & Auto Repeating
Too Many Buttons, Not Enough InputsAssigning one GPIO input to each button can use up a lot of GPIO pins. Numeric input requires at least 10 buttons, plus however many additional control or function buttons. This can quickly get expensive, GPIO pin-wise, and also connector-wise if the keypad is off the uC PCB as it often would be. A very common response to this expense is to wire buttons (keys, etc) in a matrix. By connecting our buttons in an...
BGA and QFP at Home 1 - A Practical Guide.
It is almost universally accepted by the hobbyists that you can't work with high-density packages at home. That is entirely incorrect. I've been assembling and reflowing BGA circuit boards at home for a few years now. BGAs and 0.5mm-pitch QFPs are well within the realm of a determined amateur.
This series of articles presents practical information on designing and assembling boards with high-density packages at home. While the focus is on FPGA packages, most of...
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...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...
