Main components:

- 8 Channel DC 12V Relay Module with ULN2803 driver and 12V to 5V DC-DC converter installed;
STM32F103C8T6 aka Blue Pill module;
Wizchip Ethernet W5500 module;
- two 8-dip switches;
- prototype printed circuit panel (green colored about having metalized holes).

The toolchain: MinGWGNU-ARM-GCCVSCodeSTM32CubeMX and STM32 ST-LINK Utility.

This IP-relay module is wired to the home router, that is located in the same cabinet with AC contactors for end devices. As this module intended for the management of the DIN AC relays with the electric latching, the "IPRelay/Pulse" MQTT message was programmed within the sketch. Of course, any MQTT messages can be programmed.

See "Diary" for details.