Embedded Computing Design

Printed circuit boards, i.e. PCBs, are often manufactured using an FR4 (fire retardant fiberglass) substrate, with a final thickness of 1.6mm. However, PCBs don’t have to be 1.6mm. Another common size is .8mm.

In this article, I’ll outline advantages and disadvantages of both 1.6mm and .8mm boards (in the context of a 2-layer PCB) and discuss if you should use a .8mm PCB instead of 1.6mm in your design.

The Circuit Playground Express (CPE), as outlined on Adafruit’s product page, is geared toward the educational market and for those who are just getting started with electronics. However, in my opinion, it’s also something that should be considered for more experienced makers and electronics enthusiasts when you want others to replicate your designs.

In conjunction with some WIP guitar hacking for JCo Audio, I needed a very small dev board with battery management built-in for hassle-free portable usage. Per a suggestion, I got much more than that in the form of the Seeed Studio XIAO nRF52840 Sense.

The Raspberry Pi Pico is an incredibly popular dev board, sporting Raspberry Pi’s own RP2040 microcontroller. For all its positives, one thing it lacks is native capacitive touch capability, meaning you need to add high-value (e.g. 1M) resistors to the board to allow for this type of sensing (e.g. my RP20-Footie design). While such resistors are inexpensive, they are also inconvenient to implement, thus I created a capacitive helper board that I’m calling the Pico Touch 2.*

Way back in 2020, I wrote about flashing ESP8266-based home automation devices wirelessly using a software/hardware hack called Tuya Convert to implement alternate Tasmota firmware. Unfortunately, this “vulnerability” appears to be largely patched, and most devices don’t come with easy-to-access programming through holes like the Sonoff Basic devices mentioned there. Throwing yet another wrench into the mix, the ESP32 platform is now the premier wireless networking SoC for home automation, replacing the ESP8266 in many cases.

As outlined here, I switched from PC to Mac a little over 3 years ago. Since then, I have been largely happy with my decision. Software compatibility, my biggest fear, hasn’t been a major issue. However, in preparing for my Developing With Arduino series which will feature a short intro to ladder logic programming using the Windows-only Arduino PLC IDE, I needed OS flexibility.

As outlined in previous posts, including this one from April 2023, having a 3D printer opens up a wide range of build possibilities. From an engineering perspective, this can facilitate prototyping, as well as the creation of custom implements that can be used for a wide range of purposes. Here I’ll outline several interesting prints and techniques that you may find useful in 2024 and beyond!

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.