I recently reported on my first experience with Home Assistant. The reason for this was that I wanted to collect the data from a suitably modified IKEA Vindriktning air quality sensor. The alternative firmware Tasmota, which can be used on ESP8266 or ESP32-based microcontrollers, serves as the basis for expanding the sensor. In addition, I now use the Sensirion SCD30 to measure the CO2 concentration in the room air, the relative humidity and the temperature.
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Topic: Electronics
M-Tester
A whole range of devices is available under the name “M-Tester” which can automatically detect electronic components such as transistors, diodes, resistors, capacitors, etc. and test their properties. Hence the name: “M-Tester” is the abbreviation for “Multi-function Tester”.
All products of this type go back to the article “AVR Transistortester” at mikrocontroller.net, which first described a transistor tester based on an ATmega8/168/328 and an LCD with 2×16 characters in 2012. The latest version of these devices, such as the “M-Tester T7” or “M-Tester TC1”, offers a color display with a graphic display of the components and an infrared sensor with which the function of remote controls can also be checked.
AlphaClock – old meets new
AlphaClock is the sort form of “alphanumeric clock” as the displays used can also show text. The following video was done with the first version of the firmware.
A while ago I started to deal with the topic “micro controllers”. The first trials were with an Arduino micro which I also used to test old LED displays like the HDSP-2116 or DL-2416.
One advantage of the Arduino Micro ist that it can be plugged in directly to a breadboard and has a micro USB connector for data transfer and power supply. However from LCD2USB I also know the ATmega in a DIP package. For normal operation with external clock this controller only needs a crystal and two capacitors.
My idea was to combine an ATmega328P with two DL-2416 from 1987 and a DS3231 realtime clock module. The whole thing was also a project to learn to know the development environment as Visual Studio Code and PlatformIO as well as the way how the microcontroller works in terms of interrupt control and PWM.
Hakko FX-888D
In August 2021 I bought a Hakko FX-888D soldering station. Hakko has been active in this area for decades and the products are considered to be of high quality and durable. The operation takes getting used to, but the set temperature is reached very quickly after switching on and also kept well under load.
Shift registers
If you work with microcontrollers like the ATmega328 (Arduino Uno) or ESP8266 (Wemos D1 mini) and want to control many lines at the same time, it can become a problem that there are not enough outputs are available.
One solution are shift registers. More about this in my article about the 74HC595.
Repairing a Roland Sound Canvas SC-55
In my device collection there is also a Roland Sound Canvas SC-55 which I bought used many years ago.
This is a MIDI synthesizer that came onto the market in 1991. I don’t know for sure whether my copy is that old, but an age of at least 25 years is plausible.
My little “electronics lab”
Some time ago I rediscovered my interest in electronics and recently done my first project. This project was created at the table where my PC is. However, this is not an ideal place to solder circuit boards or create designs with breadboards – I have to take the necessary parts and tools such as soldering iron, multimeter, etc. out of the drawer and then tidy up again afterwards.
HDSP-211x for Raspberry Pi – first test
Meanwhile the printed circuit boards arrived which I have ordered from Aisler based on my first draft. The quality is fine. There where only production-related burrs that I could easily sand off.
HDSP-211x for Raspberry Pi
On the project page about using LED matrix displays of the type HDSP-212x, I also showed an example setup with a Raspberry Pi. Now that I still have some of these displays, I would like to use them to build a real device in its own case.
Soldering the whole thing by hand on a perfboard would theoretically be possible, but is prone to errors and in the end you have only one copy. Nowadays there is a better solution for this: you design a circuit board with a program like KiCad and have it produced as a small series for comparatively little money.
My first draft for a board on which you can put four HDSP-211x next to each other already looks quite promising:
At AISLER, the production of three copies would cost around EUR 25 and would be ready in about a week. But before I actually do this, I’ll have to check the circuit diagram again and check whether adjustments are required for the power supply, since four modules together can have a power consumption of more than 1.6 A.
Revision 2
After taking a closer look at KiCad, I created a revised revision 2 of the layout:
- The total size of the board is a bit smaller.
- The mounting holes are now inserted as footprints and without soldier mask.
Even more fun with LED matrix displays
After my first experiment to control a single LED matrix display I extended this to two displays – and generally even more are possible:
More about this, see the project page.
