Kamstrup Multical 21 water meter in Home Assistant (Wireless MBus)

Features

• Configuration ready for Home Assistan with MQTT.
• Support for AES-128 decryption (with vaild key).
• CRC Check of recived data.
• Wireless reading of data.
• Easy to build and configure.

Parts

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CC1101 Module
ESP32 DevKit
Some cables

Wiring

CC1101	ESP32
VCC	3V3
GND	GND
CSN	P4
MOSI	P23
MISO	P19
SCK	P18
GD0	P32
GD2	Not Connected

Build and Upload Firmware

• Make sure you have a decryption key for your meter (you need to ask your water service provider for it).
• Read the serial number on the meter (typically S/N: XXXXXXXX/A/20, the serial number is the XXXXXXXXX part).
• Rename credentials_template.h to credentials.h and add your details.
• Compile and upload:
  • You need VS Code and the PIO Plugin
  • Open the project folder with the platformio.ini file (File -> Open Folder...), connect the ESP32 via USB then build and upload with Ctrl+Alt+U.

Home Assistant

Setup MQTT if you don't already have it.

Add this to configuration.yaml

mqtt:
  sensor:
    - name: "Water Meter Usage"
      state_topic: "watermeter/0/sensor/mydatajson"
      unit_of_measurement: "m³"
      value_template: "{{ value_json.CurrentValue }}"
      device_class: water
      state_class: total_increasing
      availability:
        - topic: "watermeter/0/online"
          payload_available: "True"
          payload_not_available: "False"
    - name: "Water Meter Month Start Value"
      state_topic: "watermeter/0/sensor/mydatajson"
      unit_of_measurement: "m³"
      value_template: "{{ value_json.MonthStartValue }}"
      device_class: water
      state_class: total_increasing
    - name: "Water Meter Room Temperature"
      state_topic: "watermeter/0/sensor/mydatajson"
      value_template: "{{ value_json.RoomTemp }}"
      unit_of_measurement: "°C"
    - name: "Water Meter Water Temperature"
      state_topic: "watermeter/0/sensor/mydatajson"
      value_template: "{{ value_json.WaterTemp }}"
      unit_of_measurement: "°C"

Donation using Ko-Fi or PayPal are highly appreciated!

This is a based on chester4444/esp-multical21. Thanks to chester4444for his effort.