LoraDunchy Arduino Nano pin-compatibile LoRa module with power management


Mare writes:

Lora board with Arduino nano compatibile pinout and simple battery management
Small board with arduino nano compatibile pinout with power management and Murata ABZ LoRa module with STM32L0 microcontroller
-LoRa module: Murata ABZ
-Single cell LiPo cell charger on-board with charging signal internally connected to PA11 (via jumper)
-Buck/Boost switching power supply for delivering stable 3,3V regardless of the batterz voltage
-Battery fuel gauge on-board to control the real status of the battery

See the full post on Mare & Gal Electronics blog and the GitHub repository here.

A touch numeric keyboard for Arduino or Teensy


Giovanni Carrera blogged about his touch numeric keyboard for Arduino or Teensy:

Very often, for our programs, we need a system to set parameters, usually of a numerical type. A 4×4 keyboard requires some space and then we also need a display. Here is the idea of using a touchscreen display to do both. I have then written the GetNum function that allows you to print a prompt message and to type an integer number. To test this function I wrote a simple analog data logger program that required two parameters, the first is the sampling period and the second the number of samples. In this example the number of channels to be scanned is set to three, but the program can be modified to request a third parameter with the number of channels.

See the full post on ArduPicLab blog.

Ethernet Relay board


Boris Landoni from Open Electronics writes about a new open source project Ethernet Relay board:

The project we are introducing in this article wants on to take on that task by creating, through dedicated connections, the possibility to remotely control your entrance gate, your fish tank, the garden lights, the watering system and so on, using numerous examples. It is an ethernet-controlled relay board, which can be used as an actuator to directly control 220 V loads, to command 0V ÷ 5V digital signals or to read the status of digital or analog inputs; everything can be done remotely by using an Internet capable LAN.

Full details at open-electronics.org.

EEPROM rotation for ESP8266 and ESP32


Xose Pérez over at Tinkerman writes:

The Arduino Core for ESP8266 and ESP32 uses one SPI flash memory sector to emulate an EEPROM. When you initialize the EEPROM object (calling begin) it reads the contents of the sector into a memory buffer. Reading a writing is done over that in-memory buffer. Whenever you call commit it write the contents back to the flash sector.
Due to the nature of this flash memory (NOR) a full sector erase must be done prior to write any new data. If a power failure (intended or not) happens during this process the sector data is lost.
Also, writing data to a NOR memory can be done byte by byte but only to change a 1 to a 0. The only way to turn 0s to 1s is to perform a sector erase which turns all memory positions in that sector to 1. But sector erasing must be done in full sectors, thus wearing out the flash memory faster.

How can we overcome these problems?

Full details at tinkerman.cat.

TRL measurements with homemade VNA and open source software


Henrik Forstén writes:

I have been using the OSH Park’s 4 layer process a lot on my own projects. It has FR408 substrate that has better controlled permittivity and lower losses than ordinary FR-4 that other low cost PCB manufacturers use. In my opinion currently it is the best low cost process for making RF PCBs. My previous boards have worked pretty well, but I decided to make a test board that I can use to characterize the process better.
In the above picture is the test board that I made. It has two 50 ohm microstrip lines of different length, one open microstrip line, one microstrip line terminated with 50 ohm resistor and line with 0402 footprint that I populated with a 1 nF capacitor. I’m using this same type of capacitor as a general DC blocking capacitor in my VNA so I’m interested in finding out how it performs at high frequencies.

See the full post on Henrik’s blog.

Amiga 500 power supply build


A how-to on building an Amiga 500 power supply from Inkoo Vintage Computing:

The power supply of my Amiga 500 is a bit unreliable. I’ve had some issues with the machine where the PSU could be the culprit, so I thought that it would be better to get a new power supply. There are used Amiga 500 power supplies occasionally available on online auctions, and there are also unused (but probably quite old) power supplies available on some online retailers. The issue with these 20-30 year old power supplies is that the capacitors are starting to dry. This can be a fire hazard, as old capacitors may even explode (this has happened to the PSU of my old IBM XT, it was not a pleasant experience). So in order to get safe and reliable operation from an old PSU, the capacitors should be replaced.

More details on Inkoo Vintage Computing homepage.

App note: Aluminum electrolytic capacitors design for long operational life


App note from KEMET on long life electrolytic capacitors. Link here (PDF)

The service life for high quality power supplies and automotive power electronics is often limited by electrolytic capacitors’ operational life (Lop). Very long life (> 20 years at temperature up to 75C) is possible to be achieved by choosing capacitors with optimized design. Type of electrolyte, capacitors lid design, sealing method and rubber material quality, are important factors which determine the Lop.

App note: Comparison of ceramic and tantalum capacitors



App note from KEMET about the replaceability between ceramic and tantalum capacitors to each other. Link here (PDF)

Ceramic capacitors have a multitude of dielectric types available and each of these types is characterized by their sensitivities to temparature, but not to voltage or time. This paper compares the X7R, X6S, or X5R dielectric types of ceramic capacitors with tantalum capacitors. Ceramic capacitors constructed witht these dielectrics offer moderate dielectric constants with moderate temperature and voltage sensitivities. They overlap with tantalum capacitors in capacitance/voltage range offerings. In many cases, the solder pad geometry allows swapping of ceramic 0603. 0805, 1206 or 1210 chip sizes with “J”, “R”, “A”, or “B” case tantalums, respectively.

Video tutorials: Building the Arduino based data loggers

From the comments on our Arduino data logger post:

A visiting researcher dropped by our humble basement workshop with questions about the physical skill level students would need if they added one of our DIY data loggers to their environmental curriculum. I figured the easiest way to cover that was to simply build one, while they recorded the process.
The result of that 3 hour session is now available on YouTube

Thanks Edward Mallon!

Project info at the Cave Pearl Project website.

STM32F103 vs GD32F103 round 4: SPI master


Sjaak writes, “This is part 4 in the series where we compare the STM32F103 with its Chinese counterpart the GD32F103. Both are ARM Cortex M3 microcontrollers which are mostly pin, peripheral and register compatible. Now we compare the SPI master peripheral of both chips.”

More details at smdprutser.nl.

Check out the video after the break.