Embedded Computing Design

My house has a perfectly serviceable “Lift-Master” garage door opener, installed decades before I moved in. Before, in fact, “IoT” was even a term (or practically even “I”) as its manufacturing date reads as 02/94. Nonetheless, this device’s hardwire interface–a set of dry contacts–is refreshingly easy to modernize with the addition of an IoT-controlled relay and Tasmota.

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Several years ago I ordered my first PCB, and soon after moved into the world of surface-mount devices, or SMD. In-house soldering means careful work with an iron or hot air gun, which worked well for what I was doing at the time.

In Part 1 of this custom RP2040 board series, I discussed how to build your own RP2040 dev board, and why you’d want to do so. While the process seems more straightforward to me after successfully going through it, there are many ways that a board can fail, whether through a faulty design, poor assembly, or both.

When implementing device-to-device communications you have a choice of various protocols, such as SPI, I2C, or UART. Each of those is appropriate for board-level and/or short-distance, low-speed communications. Often overlooked in some circles–though used widely in others–the CAN (Controller Area Network) protocol presents a number of compelling advantages.

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The Raspberry Pi Pico, Pico W, and other boards based on the RP2040 present a wide range of use possibilities. At the same time, this limits you to what is currently on the market. Perhaps you want something like a Pico, but with 8MB of Flash, a USB-C port, and mounting holes. Or, maybe you’d like to integrate a bare RP2040 and associated components into your larger design.

In a previous article, I went over how you to use a MAX98357 amplifier breakout to power a speaker via digital I2S (Inter-IC Sound) signals. While this opens up audio output possibilities, it’s not meant to work with an external amplifier. For that you’ll need a simple DAC, or digital-to-analog converter.

In my most recent Budget Tools Review I discussed the extremely versatile Digilent Analog Discovery 3 (DA3). One might call it a computer-based oscilloscope, but it’s much more than that. Today I’ll be using it, along with its companion software package Waveforms, as a Logic Analyzer and Protocol Analyzer to dive into I2C.

Several years ago I got to try out Digilent’s Analog Discovery 2, which is a fantastically capable computer-based test tool. It can act as an oscilloscope, power supply, logic analyzer, and much more.

Capacitive touch sensing, as discussed in my “RP20-Footie” post, as well as in class 6 of my Developing with Pi series, can be a great way to turn things on and off at a moment’s notice. But what about using a capacitive input as an analog device, such as a slider?

After creating the RP20-Footie capacitive foot (hand, or other body part) interface, I realized there was a small problem. It is very hard to get into the standard 4 x 8in bubble mailer that I use to send most of my small boards. Sure, I could use a larger box or mailer, but efficiency and inventory management is the name of the game at jcdevices.com. As of now, I do all the packaging myself, and inventory resides in a closet.

As discussed in class 7 of my Developing with Pi series, Sound and Music Output with the Raspberry Pi RP2040 Pico, the Raspberry Pi Pico/RP2040 is a rather impressive sound source. Not only is it able to generate programmatic beeps and boops as you might expect from an Arduino Uno and the like, but it can also play uncompressed WAV files, as well as compressed MP3s. The big restriction is that the Pico only has 2MB of Flash memory, though the RP2040 can work with up 16MB, allowing for a bit more room depending on your board.

CircuitPython is a programming language used on a wide variety of dev boards and microcontrollers. This includes the Raspberry Pi Pico, which I use extensively for demos in the Developing with Pi webinar series. While the RP2040-based Pico can be used with Arduino C and the Arduino IDE, what is interesting about CircuitPython in this context isn’t the language itself so much as the programming process.

Since you’re reading this, it’s safe to assume that you’re an engineer or other technically interested individual. You’ve probably even taken apart several things over your lifetime to observe the electronic workings inside. Open Circuits, by Eric Schlaepfer and Windell H. Oskay, is a celebration of this hidden world and a tool that will expand your knowledge of everything from resistors, to SOCs, Nixie tubes, and more.

Signal modulation is fundamental to radio communications, and amplitude modulation (AM) could be considered its most basic form. To understand modulation you need to have a firm grasp on several concepts and terms. In this article I’ll explore amplitude modulation in an interactive manner with the UNI-T UTG932E signal generator.

While Autodesk Fusion 360 is by nature a 3D design package, what if you need a 2D format file for use with tasks like laser cutting and PCB design? Generating a 2D DXF (Drawing Exchange Format) file is surprisingly easy if you know where to look.

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If you’ve followed my work for any length of time, you may have noticed that I’m constantly pursuing the “perfect” computer interface. This has resulted in my cycling through a number of input devices, and even developing my fully custom JC Pro Macro 2 keypad. However, I really only have two out of four appendages well-optimized, and in this interface quest I also tried using a foot pedal, as discussed here.

Should you use through hole technology (THT) or surface mount devices (SMD) for your next design? While SMD opens a whole new world of miniature components and machine assembly, if you’re designing something for others to solder in kit form, THT can be more accessible.