---
title: DHT22 temperature/humidity sensor on a NodeMCU 0.9 with ESPHome and Home Assistant
date: 2021-04-11
summary: Wiring and ESPHome YAML for a DHT22 on an old yellow NodeMCU 0.9 board, feeding Home Assistant. USB uploads failing with "Upload with baud rate 460800 failed" were fixed by disconnecting the sensor while flashing.
tags: esphome, home-assistant, esp8266, nodemcu, dht22, iot
environment: ESPHome (Home Assistant add-on, 2021); NodeMCU v0.9 (ESP-12); DHT22 / AM2302
author: shaun
status: published
aliases: Home-Assistant-ESPHome-NodeMCU-DHT22-temperature-and-humidity-sensor.html
---

![Yellow NodeMCU 0.9 board](nodemcu-0-9.png)

## Setup

In Home Assistant's **ESPHome** tab create a new node. For the device type pick
**Other ESP8266s → NodeMCU 0.9**, add Wi-Fi credentials, then edit the YAML. The
[DHT sensor docs](https://esphome.io/components/sensor/dht.html) list the options.

```yaml
esphome:
  name: node-mcu-09

esp8266:
  board: nodemcu

wifi:
  ssid: "your-ssid"
  password: "your-wifi-password"
  ap:                              # fallback hotspot if Wi-Fi fails
    ssid: "Node Mcu 09 Fallback Hotspot"
    password: "fallback-password"

captive_portal:
logger:
api:
ota:
  - platform: esphome

sensor:
  - platform: dht
    model: DHT22
    pin: D2
    temperature:
      name: "Temperature 1"
    humidity:
      name: "Humidity 1"
    update_interval: 60s
```

(Written in 2021 with `platform: ESP8266` under `esphome:`; current ESPHome wants the
separate `esp8266:` block shown above.)

Wiring:

```text
3.3V -> DHT22 VCC
D2   -> DHT22 DATA
GND  -> DHT22 GND
```

The DHT22 datasheet recommends a **4.7 kΩ pull-up** between VCC and DATA. Bare sensors need
one; most breakout boards already have it.

## Symptoms: upload over USB fails

Re-flashing over USB later failed every time with:

```text
Upload with baud rate 460800 failed. Trying again with baud rate 115200.
```

The same happened with other NodeMCU boards.

## Fix

Disconnect the sensor wires from the board's pins while flashing, then reconnect them.
Something on the attached pins was getting in the way of the boot/flash sequence (D2 itself
is not a strapping pin, so the exact cause is unproven). Once the first image is on the
board, OTA updates over Wi-Fi avoid the problem.