Thermometer (BME680)

A comprehensive environmental sensor using BME680 that broadcasts temperature, humidity, pressure, and air quality via BTHome.

Hardware

Seeed XIAO BLE (nRF52840)
BME680 sensor module (I2C)
3.7V LiPo battery

Wiring

BME680	XIAO Pin
VIN	3V3
GND	GND
SDA	D4 (pin 4)
SCL	D5 (pin 5)

graph LR
    subgraph XIAO["Seeed XIAO BLE"]
        V3["3V3"]
        GND["GND"]
        D4["D4 (SDA)"]
        D5["D5 (SCL)"]
    end

    subgraph BME680["BME680 Sensor"]
        VIN["VIN"]
        SGND["GND"]
        SDA["SDA"]
        SCL["SCL"]
    end

    V3 --- VIN
    GND --- SGND
    D4 --- SDA
    D5 --- SCL

    style BME680 fill:#e6ffe6,stroke:#333

Configuration

esphome:
  name: thermometer-bme680
  friendly_name: Environment Sensor

nrf52:
  board: xiao_ble
  bootloader: adafruit

logger:

external_components:
  - source:
      type: git
      url: https://github.com/dz0ny/esphome-bthome
      ref: main
    components: [bthome]

# I2C bus
i2c:
  sda: 4
  scl: 5
  scan: true

# Battery monitoring
sensor:
  - platform: adc
    pin: 29
    id: battery_voltage
    name: "Battery Voltage"
    update_interval: 60s
    filters:
      - multiply: 2.0

  - platform: template
    id: battery_percent
    name: "Battery"
    unit_of_measurement: "%"
    lambda: |-
      float voltage = id(battery_voltage).state;
      float percent = (voltage - 3.0) / (4.2 - 3.0) * 100.0;
      if (percent > 100) percent = 100;
      if (percent < 0) percent = 0;
      return percent;
    update_interval: 60s

  # BME680 sensor
  - platform: bme680
    address: 0x77
    temperature:
      id: bme_temperature
      name: "Temperature"
      oversampling: 16x
    humidity:
      id: bme_humidity
      name: "Humidity"
      oversampling: 16x
    pressure:
      id: bme_pressure
      name: "Pressure"
    gas_resistance:
      id: gas_resistance
      name: "Gas Resistance"
    update_interval: 60s

  # Air Quality Index (simplified calculation)
  - platform: template
    id: air_quality
    name: "Air Quality"
    unit_of_measurement: "%"
    lambda: |-
      // Simple AQI: higher resistance = better air quality
      float resistance = id(gas_resistance).state;
      // Typical range: 10k-300k ohms
      float quality = (resistance - 10000) / (300000 - 10000) * 100;
      if (quality > 100) quality = 100;
      if (quality < 0) quality = 0;
      return quality;
    update_interval: 60s

# BTHome broadcast
bthome:
  min_interval: 30s
  max_interval: 60s
  tx_power: 4
  sensors:
    - type: battery
      id: battery_percent
    - type: temperature
      id: bme_temperature
    - type: humidity
      id: bme_humidity
    - type: pressure
      id: bme_pressure

# Deep sleep for battery savings
deep_sleep:
  run_duration: 30s
  sleep_duration: 5min

Sensor Specifications

Measurement	Range	Accuracy
Temperature	-40 to +85°C	±1.0°C
Humidity	0 to 100%	±3%
Pressure	300 to 1100 hPa	±1 hPa
Gas	VOC detection	Relative

Power Consumption

State	Current
Deep sleep	~3µA
Sensor reading	~12mA
BLE TX	~15mA

Expected battery life: 3-6 months with 400mAh battery (5min intervals)