ESP-Temperature Sensor for Ponds or Pools using Home Assistant and MQTT Integration

TL;DR

A sketch for an ESP 8266 based micro controller and an DS18B20 temperature sensor to measure the temperature of a pond or pool using Home Assistant and MQTT.

The Software

Sketch

MQTT

I use the Mosquitto Broker which fits my requirements perfectly. You can also find an official Docker Image of it. I recommend a GUI based client like MQTT Explorer or MQTT.fx for testing purposes.

Topics and Messages

Once the sensor is running, you'll find three new topics on your broker:

Configuration (for MQTT Discovery)

(see also: MQTT Discovery) homeassistant/sensor/sensorPondT/config

{
 "device_class":"temperature",
 "name":"Pond Temperature",
 "object_id":"pond_temperature",
 "state_topic":"homeassistant/sensor/sensorPondT/state",
 "availability_topic":"homeassistant/sensor/sensorPondT/status",
 "json_attributes_topic":"homeassistant/sensor/sensorPondT/attributes",
 "unit_of_measurement":"°C",
 "value_template":"{{ value_json.temperature}}"
}

State - Temperature

homeassistant/sensor/sensorPondT/state

{"temperature":14.9375}

Attributes

This topic imcludes additional attributes which will be added to the configured sensor. "homeassistant/sensor/sensorPondT/attributes"

{
 "battery_voltage":2.9455078125,
 "battery_status":89.2578125,
 "RSSI":-81
}

Status

This indicates if the sensor is availble or not.

homeassistant/sensor/sensorPondT/status

online | offline 

The Hardware

The Wiring

Configure the Buck Converter

The Configuration

The Home Assistant Integration

Sensor

View (Example)

- type: gauge
  entity: sensor.pond_temperature
  name: Pond Temperature
  unit: "°C"
  needle: true
  min: -5
  max: 35
  severity:
    red: 0
    yellow: 10
    green: 20

The Case