Home Assistant: Water consumption monitoring with gPlugD-E and Ensor eRS801 via P1-DSMR interface in ESPHome

Hey, my name is "Tux" and this tutorial will show you how to set up water consumption monitoring in Home Assistant with ESPHome, a gPlugD-E adapter, connected to the P1-DSMR interface of an Ensor eRS801 smart meter.

Preparation

First of all, if you want to catch any data of an Ensor eRS801 its P1-DSMR customer interface, you have to make sure the customer interface is being unlocked. In my case, the electrician hired by the municipality from the village I live, which installed the Ensor eRS801, took care on this for me. I also asked him to set down the Ensor eRS801 its internal request interval to the physical water meter (which is an Integra aquastream Type AQS-MB in my case) to an interval of 60 seconds instead of default 3600 seconds. This way I could monitor at least consumed liters per minute, which is sufficient for my needs. He also had to tell me on which M-Bus channel the water metering communication is being transferred, which is channel #4 in my case. If the channel number differs in your case, please just adjust the number accordingly on the YAML code provided later in this tutorial.

In addition, in case you need it, because I was not able to find anything documented officially and therefore had to trial and error, here's on how to bring the gPlugD-E adapter into flashing mode: Press and hold the R-button (1), then press and hold the A-button (2), then release the R-button (1) and finally release the A-button (2). Now you can flash your custom .bin firmware file via web.esphome.io web interface. Be aware, that after successful flashing, you need to press the R-button at least once again to reset the gPlugD-E adapter to make the uploaded program start running. It was somehow not sufficient in my case to press the virtual device reset button on the web.esphome.io web interface.

gPlugD-E physical buttons

First thoughts & tutorial

While searching for a way to track my water usage in Home Assistant after the municipality had ruined my original, well-functioning solution with their new installation, I came across this alternative. Should be an easy task, right? Using the main YAML code from the linked tutorial, replacing the power monitoring code part with my own water monitoring part, flashing it via ESPHome to the gPlugD-E adapter and I will be ready to go…
But wait: The problem I stumbled across was that the gPlugE adapter from the linked tutorial is not available anymore and has being replaced with its successor, the gPlugD-E adapter. The underlying hardware is not the same anymore and internal microcontroller pin connections to the physical ethernet interface have changed. So I had to determine the new board its layout by myself.

I contacted the gPlugD-E support but they were not willing to help me out with this so I flashed back the gPlugD-E its original Tasmota firmware, opened its web console and tried to determine the according pin layout by executing the following command:

Template

Which gave me the following output:

{"NAME":"IoT-Adapter","GPIO":[736,672,5536,704,0,0,0,0,5600,0,5568,0,0,0,0,0,0,0,0,0,0,0]}

Seems like an array of GPIO mapping values, which I could use to compare against the official Tasmota GPIO conversion table, right? Unfortunately not. I was not able to find those array values within the conversion table, so the logic behind it must be different. My bad, I guess.

So I asked claude.ai to help me and it told me to execute the following command on the Tasmota console:

gpio all

…and voilà:

17:47:27.464 RSL: RESULT = {"GPIO0":{"SPI CLK1":736},"GPIO1":{"SPI MISO1":672},"GPIO2":{"ETH POWER":5536},"GPIO3":{"SPI MOSI1":704},"GPIO4":{"None":0},"GPIO5":{"None":0},"GPIO6":{"None":0},"GPIO7":{"None":0},"GPIO8":{"ETH MDIO":5600},"GPIO9":{"None":0},"GPIO10":{"ETH MDC":5568},"GPIO11":{"None":0},"GPIO12":{"None":0},"GPIO13":{"None":0},"GPIO18":{"None":0},"GPIO19":{"None":0},"GPIO20":{"None":0},"GPIO21":{"None":0}}

All the required pin mappings are there. Now I got everything I needed to configure the ethernet port via YAML code accordingly, which worked perfectly. Yay!

Now the ESPHome YAML code to read out data via DSMR protocol standard was indeed simple and minimal. But the next problem was right around the corner: Data was being transmitted successfully, but the default DSMR library from ESPHome was not able to parse the data output accordingly, it mostly had something to do with missing or false timestamp format, but I cannot tell for sure as I never analyzed the whole raw data stream. No worries. In the end I had to prompt Claude again to help me out with this and it gave me the following perfectly working code solution:

# Ethernet:
ethernet:
  type: W5500
  clk_pin: GPIO0
  mosi_pin: GPIO3
  miso_pin: GPIO1
  cs_pin: GPIO10
  interrupt_pin: GPIO8
  reset_pin: GPIO2
 
# Globals:
globals:
  # Globals for water consumption calculation
  - id: water_m3
    type: float
    restore_value: true
    initial_value: '0.0'
  - id: tbuf
    type: std::string
    initial_value: '""'
  - id: tactive
    type: bool
    initial_value: 'false'
 
# Sensors:
sensor:
  # Water consumption
  - platform: template
    id: water_sensor
    name: "Water consumption"
    unit_of_measurement: "m³"
    accuracy_decimals: 3
    device_class: water
    state_class: total_increasing
    icon: "mdi:water"
    lambda: return id(water_m3);
    update_interval: 5s
 
# UART:
uart:
  id: uart_bus
  rx_pin: GPIO4
  baud_rate: 115200
  rx_buffer_size: 2048
 
# Interval-driven data parsing
interval:
  # Check for incoming data over serial every 100ms
  - interval: 100ms
    then:
      - lambda: |-
          while (id(uart_bus).available() > 0) {
            uint8_t b;
            id(uart_bus).read_byte(&b);
            char c = (char) b;
            if (c == '/') {
              id(tbuf) = "";
              id(tactive) = true;
            }
            if (!id(tactive)) continue;
            id(tbuf) += c;
            if (id(tbuf).size() > 2000) {
              id(tbuf) = "";
              id(tactive) = false;
              continue;
            }
            if (c == '!') {
              const std::string pfx = "0-4:24.2.1(";
              size_t p = id(tbuf).find(pfx);
              size_t s = id(tbuf).find('*', p);
              if (p != std::string::npos && s != std::string::npos) {
                p += pfx.size();
                float v = atof(id(tbuf).substr(p, s - p).c_str());
                if (v > 0.0f) id(water_m3) = v;
              }
              id(tbuf) = "";
              id(tactive) = false;
            }
          }

Now, if you don't have yet, adapt the gPlugD-E adapter in Home Assistant and you'll have the ''Water consumption" sensor available which you can use to add water consumption monitoring on the Home Assistant Energy Dashboard.