USB mini media keyboard


Sven Krasser built a small USB keyboard input device for media control and wrote a post on his blog detailing its assembly:

The project is based on a Pro Micro, an Arduino-compatible ATmega 32u4 board (the 32u4 allowing to easily create USB devices). For iteration 1, I added a couple of buttons and a rotary encoder to a breadboard alongside the Pro Micro to see how I can get media controls over USB to work. Turns out, Nico Hood’s HID library makes that quite simple.

Minimal ATSAMD21 computer


Johnson Davies shared detailed instructions of how to build an ATSAMD21-based computer on a prototyping board using a 32-pin ATSAMD21E:

If you’re looking for something more powerful than the ATmega328 in the Arduino Uno a good choice is the ATSAMD21. This is an ARM Cortex M0+ processor with up to 256KB flash memory, 32KB RAM, and a 48MHz clock, so it’s substantially better equipped than the ATmega328. In addition it has a USB interface built in, so there’s no need for a separate chip to interface to the serial port.
Arduino have designed several excellent boards based on the ATSAMD21, such as the Arduino Zero or smaller-format MKRZERO. However, these boards are an expensive way to use an ATSAMD21 as the basis for your own project, and they probably include many features you don’t need.

More details on Technoblogy.

Arduino interface for TFA9842AJ power amplifier


Dilshan Jayakody writes, “I tested a couple of TFA9842AJ based amplifiers in the last couple of years. The main reason I liked TFA9842AJ is its simple, clean design, wide operating voltage, and high-quality bass-rich audio output.  Thanks to it’s built-in DC volume control circuit this audio amplifier can easily interface with MCU. In this article, we provide a generic TFA9842AJ module which works with most of Arduino boards, MCUs and SOCs.”

See the full post in his blog.

Arduino Shield for CAT M1 and NB-IoT modems


Michael Krumpus designed and built an Arduino shield for Nimbelink Skywire CAT M1 and NB-IoT modems, that is available on Github:

Nimbelink has a development kit for use by product developers, but it’s rather expensive. I wanted to try out a Nimbelink CAT M1 modem without the dev kit, and since there are so many hobbyists using Arduinos out there, I wanted to provide a nice Arduino library for the modem. I chose the Nimbelink module based on the Sequans Monarch CAT M1 modem and got to work designing an Arduino shield to hold it.

More details on Nootropic design Project Lab site.

An Arduino version of Brooks Shera’s GPSDO


Jeff (aka K6JCA) has a great write-up on implementing the Brooks Shera Phase-Locked Loop GPSDO on an Arduino Platform:

This blog post is a continuation of my two earlier GPSDO blog posts. The first one (from a few years back) details a simple Frequency-Locked Loop GPSDO design, based around an Arduino processor. The second (more recent) blog post discusses simulating Brooks Shera’s GPSDO algorithm (from the July, 1998 issue of QST) using The MathWorks Simulink program.
This third blog posts describes my modification of my original Frequency-Locked Loop (FLL) GPSDO to be a Phase-Locked Loop (PLL) GPSDO, and it includes the hardware schematics, Simulink models, and the Arduino code I wrote to implement Brooks Shera’s GSPDO algorithm on an Arduino processor.

More details on K6JCA blog.

Irrighino and Yun Rev.2

Irrighino has been one of my most appreciated projects: it’s a automatic irrigation system – based on Arduino Yun – with a web-based interface, optimized for smartphones.

After having published the project on this blog, it was reviewed by Open Electronics and a dedicated shield was also produced. The shield is still sold on Futurashop:


When it was launched the new Arduino Yun (named Rev.2) and the Yun Shield, the Linux distribution running on the board, OpenWrt, was updated as well. In particular, a key component for Irrighino has been replaced with its newer version, the php engine.

If you own a “first generation” Arduino Yun and you’d like to test the new functionalities shipped with Rev.2, in this post I explain how you can update the operating system of your board!

The commands you have to issue on your Yun to install all the required components for Irrighino now are:

install php with cgi and cli

opkg install php7 php7-cgi php7-cli

install curl, json and sqlite modules

opkg install php7-mod-curl php7-mod-json php7-mod-pdo php7-mod-pdo-sqlite

install zoneinfo

opkg install zoneinfo-core zoneinfo-europe

(replace zoneinfo-europe with the one related to your continent)

Final step is to configure the uhttpd webserver to run the php engine.

Edit the /etc/config/uhttpd file adding the following line (pay attention to its position!):


then restart the webserver with:


Now the Yun is ready to run Irrighino!

Pro mini logger project for the classroom


Edward Mallon writes:

Dr. Beddow’s instrumentation class has been building the 2016 version of the Cave Pearl datalogger for more than three years, and feedback from that experience motivated a redesign to accommodate a wider range of student projects while staying within the time constraints of a typical lab-time schedule. The rugged PVC housing from the older build has been replaced with an inexpensive pre-made box more suitable for “light duty” classroom deployment. The tutorial includes a full set of youTube videos to explain the assembly. We hope this simplified build supports other STEM educators who want to add Arduino-based experiments to their own portfolio of activities that develop programming and “maker” skills.

Via the comments.  More details on Underwater Arduino Data Loggers blog.