Quest for lower electricity consumption - WeMos D1 Mini R2

WeMos D1 Mini is an ESP8266 WiFi board compatible with Arduino. OpenTherm shield and library should support it so switch from Arduino Uno should be easy... Of course, it was not :-)

First let's wire it correctly. I've seen complain on github it does not work with some pins. Here is my wiring which works for me:

• OpenTherm jumper set to 3.3V
• OpenTherm D3 - WeMos D1 (via header) : #define BOILER_IN 5
• OpenTherm D5 - WeMos D5 (via header) : #define BOILER_OUT 14
• OpenTherm 3.3V - WeMos 3.3V
• OpenTherm GND - WeMos GND

Picture which shows both leds blinking (ON and RxB leds) - proof it works:

If you, for example, connect 5V from WeMos to 5V on OpenTherm shield, it will not work (it took me almost an hour to figure it out).

My code is based on examples how to connect to wifi, use https client and send a POST request (you can easily open them from Arduino IDE  via menu File - Examples - ESP8266HTTPClient).

Data for every message type is sent to a webhook in Home Assistant (message id is suffix in webhook name). Sensor configurations are straightforward except conversion of bit mask to binary sensor:

template:
  - trigger:
      - platform: webhook
        webhook_id: boiler0
    sensor:
      - name: Boiler - updated at
        unique_id: boilerupdate
        state: "{{ as_timestamp(now())|timestamp_custom('%d. %m. %Y %H:%M:%S') }}"
        icon: mdi:clock-time-four-outline
    binary_sensor:
      - name: Boiler - error
        unique_id: boiler0fault
        state: "{{ trigger.json.data|int|bitwise_and(1) > 0 }}"
        device_class: problem
      - name: Boiler - central heating
        unique_id: boiler0ch
        state: "{{ trigger.json.data|int|bitwise_and(2) > 0 }}"
        device_class: running
      - name: Boiler - warm water
        unique_id: boiler0dhw
        state: "{{ trigger.json.data|int|bitwise_and(4) > 0 }}"
        device_class: running
      - name: Boiler - heating
        unique_id: boiler0flame
        state: "{{ trigger.json.data|int|bitwise_and(8) > 0 }}"
        device_class: running
  - trigger:
      - platform: webhook
        webhook_id: boiler18
    sensor:
      - name: Boiler - pressure
        unique_id: boiler18
        state: "{{ trigger.json.data }}"
        state_class: measurement
        device_class: pressure
        unit_of_measurement: bar
        icon: mdi:speedometer
...

Using all sensors, I've created a dashboard in Home Assistant to have a full picture how the boiler works :

But my joy did not last long - within 1-2 hours, the data stopped flowing :-( Next post will be about figuring why?

PS: The above image is from future when the issue is fixed.