ESP-32 home sensor

ESP32 DevKit v1 home sensor connected via I2C to a BME280 sensor which measure temperature, humidity and pressure. Measurements are sent over MQTTv5 to Mosquitto MQTT broker which are then consumed by Telegraf and persisted into InfluxDB.

Overview

flowchart LR
    A(fa:fa-microchip ESP32<br /><small><i>outdoor front</i></small>)
    B(fa:fa-microchip ESP32<br /><small><i>indoor living room</i></small>)
    C(fa:fa-microchip ESP32<br /><small><i>indoor bedroom</i></small>)
    D(fa:fa-tower-broadcast Mosquitto MQTT)
    E(fa:fa-gear Telegraf)
    F(fa:fa-database InfluxDB)
    G(fa:fa-chart-line Dashboards)

    A-->D
    B-->D
    C-->D
    D-->E
    E-->F
    F-->G

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Getting started

ESP32

Requirements

• espflash
• espmonitor
• espup

Pin-out

Sensor	Pin Sensor	ESP32 DevKit v1 Pin
BME280	SDA	GPIO 21 / D21
BME280	SCL	GPIO 22 / D22
BME280	GND	GND
BME280	3.3v	3v3
SCD30	SDA	GPIO 21 / D21
SCD30	SCL	GPIO 22 / D22
SCD30	GND	GND
SCD30	3.3v	3v3
SDS011	RX	GPIO 17 / U2:TXD
SDS011	TX	GPIO 16 / U2:RXD
SDS011	GND	GND
SDS011	5v	3v3

Note: I2C devices share the same I2C bus (BME280, SCD30).

Configuration

Before flashing the device, you will need to configure parameters in the ./cfg.toml file, for example:

[esp32_home_sensor]
wifi_ssid = "my-wifi"
wifi_psk = "wifi-password"
hostname = "esp32-outdoor"
mqtt_hostname = "homie.local"
mqtt_port = 1883
mqtt_username = "esp32-outdoor"
mqtt_password = "someranddompassword"
mqtt_topic = "sensors"
measurement_interval_seconds = 300
location = "outdoor"

Development

Connect the device via USB, then run the following command to run flash and retrieve logs from the device using espmonitor:

espup install

. $HOME/export-esp.sh

cargo run --release

# or run specific features/sensors
cargo run --release --features json,bme280 --no-default-features

Flashing

Connect the device via USB, then flash it with the following command:

. $HOME/export-esp.sh
cargo espflash flash --release

Available features

The following Cargo features allow you to enable/disable sensors and select the MQTT message format to use:

Feature	Description	Default
bme280	Enable BME280 sensor	yes
sds011	Enable SDS011 sensor	yes
influx	Set MQTT payload format to Influx	no
json	Set MQTT payload format to Json	yes

For example, to only enable BME280 with JSON format:

. $HOME/export-esp.sh
# enable BME280, SDS011 with MQTT message in JSON format (default)
cargo espflash flash --release

# enable BME280 with MQTT message in INFLUX format
cargo espflash flash --release --features influx,bme280 --no-default-features

Setup infrastructure using Docker

Docker compose is used to setup the infrastructure. It is composed of 4 services:

• InfluxDB - persistent storage and basic dash-boarding
• Mosquitto - MQTT broker
• Telegraf - consume MQTT messages and store them in the database
• A bash job to setup InfluxDB user/token

First, review/adjust environment variables in ./infra/influxdb.env. Then, for each device (one per line) define a username/password in ./infra/mqtt.auth file. For example:

esp32-outdoor:a19sn#sA94k!a5o10
esp32-indoor:a93KifAoBf7#01-jl

After what, run docker compose up -d to deploy the infrastructure.

Note, you might have to restart all containers to get the environment variables re-populated into the container after being generated during initial boot.

You can visualise metrics by importing ./infra/influx-dashboard.json as dashboard into InfluxDB.

Setup Home Assistant or other providers

It's possible to change the payload format of the MQTT message to JSON instead of Influx by using the --features json.

Refer to the Home Assistant documentation for details on how to set this up.