This is a ESPHome based Hichi/Volkszähler interface specifically for the Holley DTZ541 that has alignment pins instead of the more common round indent around the IR interface.

UPDATE 2023-01-29

Previously mentioned issues with the Adafruit QT Py S2 have been resolved in this newer configuration. The LED is not yet used for feedback but that functionality will be added later.

Required Hardware

• Adafruit QT Py ESP32-S2 with u.FL
• Hichi/Volkszähler IR Interface PCB
• u.Fl to RP-SMA cable short (or shorten yourself and resolder on RP-SMA side)
• RP-SMA WiFi antenna, potentially with extension depending on location
• Wires for soldering
• USB-C cable and charger
• Neodym Ring Magnet either 27/16x5 mm (recommended) or 27/21x3 mm

Prints

The main housing can be printed with or without the logo. For the Prusa MK3/S/S+ there is also a gcode file available with a manual color switch right at the start of the print if you don't have a multi material printer. (Start printing in black and switch to white)

The main housing is designed for the neopixel LED to shine through as a square notification LED. As mentioned before this feature will be added later or you could just adjust the configuration yourself.

The bottom interface should be printed in black to limit light bleeding from the LED to the sensor.

Assembly

The assembly should be pretty self explanatory only quirk depending on the IR board you are using is that you might not need to cross RX and TX so make sure to read the board documentation.

Make sure to orient the wires like shown in the following pictures so they match the wire slots in the prints. Also do not use too much solder or the board won't sit flush.

ESPHome Configuration

The attached basic configuration offers a starting point for your own configuration. There are more optional OBIS codes available for the meter that can be unlocked by a pin.

Do not try to read the OBIS code for the serial number as a string (hex is fine) as it has unknown characters that will cause issues, crashing the software.

Notes

Optimized to be printed with a layer height of 0.2 mm and a nozzle size of 0.4 mm.

Made with the personal version of Autodesk Fusion 360 therefore non commercial only.

Source file included.