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.
If you want to control many I/O ports with a microcontroller you can use shift registers like the 74HC595. This solution is quite cheap but requires three lines to control and only works in one direction. If you also want to read in data you need another chip like the 74HC165 and additional lines if you want to have this parallel to the output.
A much more flexible solution is the port expander MCP23017. This chip will be controlled using I2C and provides 16 ports which can be configured individually as input or output.
There is also the variant MCP23008 with less ports and the variant MCP23S17 with SPI instead of I2C.
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.
There are numerous replicas of the Arduino Uno, some with a different structure. What most replicas have in common is that they use a USB-TTL converter CH340 instead of their own controller for the USB connection. However, the connection to the Arduino IDE is made in the same way via a serial interface and the Arduino Uno bootloader required for this also works with these boards and is usually already available.
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.
For example: to control an HD44780-compatible LCD at least 6 lines are required if it is operated in 4-bit mode. However with a Wemos D1 mini there are only 11 outputs available or 9 if you want to use the serial data lines. If 6 lines are only used for the display, only 5 or 3 lines are available for other purposes. This can still be sufficient in some cases – but if you also want to connect sensors or buttons to control the unit, this may not be enough.
The following list shows the assignment of the connections of the ATmega 328P according to the designations in the Arduino IDE when compiling code for the Arduino Uno. You need this information if you want to use the controller as a single chip in your own circuit.