How to configure sensor for MQTT to totalize rainfall data

Good day,

I have a rainfall tipping bucket from DFRobot which uses a library that provides raw data (number of tips), rainfall in the previous hour, total sensor up time and total rainfall during sensor uptime.

I want to use the pubsub library to send the data through to Home Assistant, where I want to historize the rainfall data.

Code for Raspberry Pi Pico connected via I2C to Rainfall Sensor:

#include "DFRobot_RainfallSensor.h"
#include <PubSubClient.h>
#include <WiFi.h>

DFRobot_RainfallSensor_I2C Sensor(&Wire);

// Replace with your network credentials
const char* ssid = "My SSID";
const char* password = "My Password";

// MQTT broker details
const char* mqtt_server = "My HA IP Address with MQTT Broker";
const int mqtt_port = 1883;
const char* mqtt_topic_rain = "rainfall";
const char* mqtt_username = "mqttUser";
const char* mqtt_password = "password1";

uint32_t prevRain = 0;

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(callback); // Define the callback function

    delay(1000);
  while(!Sensor.begin()){
    Serial.println("Sensor init err!!!");
    delay(1000);
  }
  Serial.print("vid:\t");
  Serial.println(Sensor.vid,HEX);
  Serial.print("pid:\t");
  Serial.println(Sensor.pid,HEX);
  Serial.print("Version:\t");
  Serial.println(Sensor.getFirmwareVersion());

}

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP8266Client", mqtt_username, mqtt_password)) {
      Serial.println("connected");
      client.subscribe(mqtt_topic_rain);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
  uint32_t rain;
 //Get the sensor working time, unit: hour
  Serial.print("Sensor WorkingTime:\t");
  Serial.print(Sensor.getSensorWorkingTime());
  Serial.println(" H");
  //Get the accumulated rainfall during the sensor working time
  Serial.print("Rainfall:\t");
  Serial.println(Sensor.getRainfall());
  //rain = Sensor.getRawData();
  //Get the accumulated rainfall within 1 hour of the system (function parameter optional 1-24)
  Serial.print("1 Hour Rainfall:\t");
  Serial.print(Sensor.getRainfall(1));
  Serial.println(" mm");
  //Get the raw data, the number of tipping buckets for rainfall, unit: times
  Serial.print("rainfall raw:\t");
  Serial.println(Sensor.getRawData());
  rain = Sensor.getRawData();
  delay(1000);

  //client.publish(mqtt_topic_rain, rain);
  if(rain > prevRain){
    client.publish(mqtt_topic_rain, "0.2974");
  }
  prevRain = rain;
  }

If I listen to the MQTT topic “rainfall” on HA, I get a 0.2794 every time I tip the bucket, which is what I want. However, the sensor entity I set up, only updates the first time I tip, and never again after that.

YAML configuration for MQTT Sensor data:

mqtt:
  sensor:
  - name: "Omeya Rain"
    state_topic: "rainfall"
    state_class: total_increasing
    device_class: precipitation
    unit_of_measurement: "mm"
    unique_id: "OmeyaRain"

image

It seems like the way I have set up my sensor, or the fact that client.publish sends a string, is preventing me from totalizing my data.

I would appreciate some help or advice.

Thank you

Think you missed one important option in your MQTT settings and see no update if there was no change the setting is:

force_update: true

With this option HA will see 0.2794 every time.
Also think you need an additional template sensor for your total (and drop “state_class: total_increasing” from your MQTT rainfall)

BTW the devil is in the detail (took me a while too)

It was good reading your topic because I notice that despite this force update I still have problems inside the next step: adding this value to my total:

  • you cannot use the trigger “platform: state” because this only acts on a changed value.
  • not sure if there is a trigger based upon an changed timestamp (anyone?)
  • at this point I did not find a way to update the template sensor with totals directly with a MQTT value (maybe someone has ideas about this)

If you receive always an identical value you may use the following trigger to update your template sensor with total rainfall:

  trigger:
    - platform: mqtt
      topic: "rainfall"

Hope this works for you, let me know.
PS If you send your MQTT-topic time based you will the same problems as I try solve.