WMBUS

Wireless M-Bus metering radio based on the Radiocontrolli RC-S2LP-868 (ST S2-LP, 868 MHz) for reading heat, water, gas, and electricity meters. Plugs into A0 BUS1 or BUS2, SPI to the ESP32-C6, powered from the slot (+3V3).

Key Features

• Wireless M-Bus (EN 13757-4), 868 MHz ISM
• SPI: SCK GPIO20 / MISO GPIO19 / MOSI GPIO18, CS GPIO2, SDN GPIO1 (BUS1)
• 1.8–3.6 V — power from J1 pin 7 (+3V3), never J3 pin 7 (FB_5V)

Image

Front PCB

Back PCB

Front Pinout

Back Pinout

Bring-up

Wireless M-Bus Testing — reset via SDN + SRES strobe, confirm PARTNUM = 0x03.

Schematics & Sources

• Schematic (PDF) — GitHub
• KiCad source — wmbus.kicad_sch
• Module README — GitHub

References

• ST S2-LP — product page · datasheet (PDF)
• RC-S2LP-868 — product page
• OMS / EN 13757-4 — specification