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Home Assistant, ESPHome, BMP280 - temperature and pressure monitoring.

List:

raspberry PI 3 or newer raspberry pi - cost about €43.09
ESP32 esp32 - cost about €3.5
microSD card - cost about €10
sensor BMP280 - temperature, pressure bmp028 - cost about €1.5
wires to connect ESP32 with BMP280
cable to power ESP32 micro usb
ethernet cable
wifi dongle
optional case for esp32 and sensor, I've made one - you can look here https://github.com/karcio/stls/blob/main/esp32_sensor_bottom_v1.scad

Raspberry Pi 3

ESP32 controller

BMP280 sensor

ESP32 custom case

Prepare image HAOS:

download HAOS for your rpi from https://github.com/home-assistant/operating-system/releases/tag/13.0

https://github.com/home-assistant/operating-system/releases/download/13.0/haos_rpi2-13.0.img.xz

unpack image

unxz haos_rpi2-13.0.img.xz

insert sd card to your device and check how your machine recognize it - in mine case it is /dev/mmcbkl0

sudo fdisk -l

flash your sdcard

sudo dd if=Downloads/haos_rpi2-13.0.img  of=/dev/mmcblk0 status=progress bs=1M

First run HA

insert sd card to RPI
connect Ethernet cable
insert WIFI dongle to usb port
connect power to RPI and wait while for HA to run
on your router check your rpi Ip address
in web browser insert rpi Ip address with port 8123, http://your_rpi_ip:8123
first create account

Setup wifi connection on first run:

go to Settings > System > select Network and then wifi tab
in ip4 select automatic
in WI-FI scan network to find your network and insert SSID and password. Save after that
reboot rpi to set up wifi

Install Add-ons:

go to : Settings > Add-ons
click in add and install esphome and File editor
esphome allows you to use esp32
file editor allows you to edit config files and check syntax

HA config structure

configuration.yml
automation.yml
secrets.yml

Connect BMP280 to ESP32

BMP280 sensor has 6 pins but we use just 4: VCC, GRN, SCL, SDA
connet pins as following:
- BMP280 VCC → ESP32 3V
- BMP280 GRN → ESP32 GRN
- BMP280 SCL → ESP32 D22
- BMP280 SDA → ESP32 D21

ESP32 and BMP280 final photos.

Connect esp32 to rpi for first initial flash

connect esp32 using usb cable to rpi do RPI
open ESPHome tab
click on add new device

this is sample of config file:

esphome:
  name: esp32-01
  friendly_name: esp32-01

esp32:
  board: esp32dev
  framework:
    type: arduino

# Enable logging
logger:

# Enable Home Assistant API
api:
  encryption:
    key: "xxx"

ota:
  - platform: esphome
    password: "xxx"

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Esp32-01 Fallback Hotspot"
    password: "xxx"

captive_portal:

i2c:
  sda: 21
  scl: 22
  scan: True

sensor:
  - platform: bmp280_i2c
    temperature:
      name: "bedroom temperature"
      oversampling: 16x
    pressure:
      name: "bedroom pressure"
    address: 0x76
    update_interval: 60s

This is how looks sample of automation config

alias: "Temperature"
description: low temperature level
trigger:
  - platform: state
    entity_id:
      - sensor.temperature
    to: null
    for:
      hours: 0
      minutes: 30
      seconds: 0
condition:
  - condition: or
    conditions:
      - condition: numeric_state
        entity_id: sensor.temperature
        above: 25
      - condition: numeric_state
        entity_id: sensor.temperature
        below: 5
      - condition: numeric_state
        entity_id: sensor.temperature
        below: 0
action:
  - data:
      message: "Temperature is: {{ states('sensor.temperature')}} C"
      title: "Warning: temperature is {{ states('sensor.temperature')}} C"
    action: notify.email_notification
mode: single

Whole documentation is here: https://www.home-assistant.io/installation/raspberrypi