Temperature Sensor (ESP32)

Temperature Sensor with ESP32

Build a wireless temperature and humidity sensor using an ESP32 and DHT22 sensor. Fully integrated with Home Assistant.

What you need

Component	Price	Notes
ESP32 board	~$5	Any ESP32-WROOM
DHT22 sensor	~$3	More accurate than DHT11
10kΩ resistor	~$0.01	Pull-up resistor
Jumper wires	~$1	For connections
USB cable	-	For programming

Total cost: ~$10

Wiring

ESP32          DHT22
─────          ─────
3.3V    ───→   VCC (pin 1)
GPIO4   ───→   DATA (pin 2)
         └──[10kΩ]──→ 3.3V
GND     ───→   GND (pin 4)

Note

The 10kΩ resistor between DATA and 3.3V is important for stable readings.

ESPHome Configuration

esphome:
  name: temperature-sensor
  friendly_name: Temperature Sensor

esp32:
  board: esp32dev

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

api:
  encryption:
    key: !secret api_key

ota:
  platform: esphome

logger:

# DHT22 Sensor
sensor:
  - platform: dht
    pin: GPIO4
    model: DHT22
    temperature:
      name: "Temperature"
      filters:
        - offset: -0.5  # Calibration if needed
    humidity:
      name: "Humidity"
    update_interval: 60s

Step-by-step

1. Prepare ESPHome

1. Open ESPHome in Home Assistant
2. Click + New Device
3. Name it temperature-sensor
4. Select your ESP32 board type

2. Add the configuration

Replace the generated config with the YAML above.

3. Flash the device

1. Connect ESP32 via USB
2. Click Install → Plug into this computer
3. Select the COM port
4. Wait for flashing to complete

4. Verify in Home Assistant

After flashing:

1. Go to Settings → Devices & Services
2. The device should appear automatically
3. Click Configure to add it

Calibration

DHT22 sensors can vary slightly. To calibrate:

1. Compare with a known accurate thermometer
2. Adjust the offset filter value
3. Positive offset = increase readings
4. Negative offset = decrease readings

Alternative: DS18B20

For waterproof applications, use DS18B20:

sensor:
  - platform: dallas_temp
    address: 0x1234567890ABCDEF
    name: "Temperature"
    update_interval: 60s

one_wire:
  - platform: gpio
    pin: GPIO4

Troubleshooting

No readings / NaN values

• Check wiring connections
• Verify the pull-up resistor
• Try a different GPIO pin

Unstable readings

• Add capacitor (100nF) near DHT22
• Reduce update_interval
• Check power supply quality

Device not connecting

• Verify WiFi credentials
• Check if ESP32 is within WiFi range
• Look at ESPHome logs for errors