Embedded Computing Design

In part 1 of this MIDI with Arduino/Microcontrollers series we explored this protocol on a very low level, i.e. 1s and 0s. In this follow-up we’ll delve even deeper, showing how MIDI connections pass signals without the electrical interference that can be the bane of musicians and engineers. You can find the newest 5-pin MIDI spec here, adapted to work with both 5 and 3.3V signaling. It’s a great document–thorough, but concise enough to easily digest.

MIDI (Musical Instrument Digital Interface) has been in use for roughly four decades as of this writing, and it is still going strong in the world of music production. As an engineer, I love a protocol that is designed to stand the test of time and features a robust connector–here a 5-pin connector formally known as a DIN 41524. Official specs are found here on MIDI.org under 5 PIN DIN ELECTRICAL SPECS.

The ATtiny series of chips–specifically the ATtiny25, ATtiny45, and ATtiny85–are incredible microcontrollers, capable of extremely low-power operation and control via just eight pins. As I will describe here, you can even implement capacitive touch sensing on these chips’ ADC pins without any external components whatsoever.

To help facilitate my recent Developing With Arduino low power class I purchased an FNIRSI FNB48S USB voltage and current tester.* In this review I’ll take you through my initial thoughts on the device, its weaknesses, and why you may want to buy one yourself.

The ATtiny 25/45/85 series is a fantastic little chip, with a low price, flexible voltage input options, and a limited number of IO pins that can be a fun optimization challenge*. It uses a minimal amount of power when compared to something like an Arduino Uno, or certainly a Raspberry Pi, but running an ATtiny constantly will still drain a CR2032 battery, or even a couple of AA cells, in a relatively short amount of time.

The Arduino Opta was announced in late 2022 as Arduino’s first foray into the world of programmable logic controllers (PLCs) which are commonly used in industrial automation. As someone who spent a considerable amount of time in that world, now deals with Arduino and Arduino-adjacent devices, I was excited to try this out as a part of my Developing With Arduino online training series. I’ll do a live demo of the device in the upcoming class 5, and in this article I’ll outline my initial thoughts on this little PLC.

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.