An app based on SimpleDHT library for the DHT series of low-cost temperature & humidity sensors, now featuring real-time updates, computer monitoring, and Wake-on-LAN capabilities with optimized performance.

You can find DHT11 and DHT22 tutorials here.

• Arduino CLI for building and uploading the code to the board

• mkspiffs + esptool, usually installed with Arduino CLI and located at:

  • C:\Users\YourName\AppData\Local\Arduino15\packages\esp32\tools\esptool_py\5.0.0\esptool.exe
  • C:\Users\YourName\AppData\Local\Arduino15\packages\esp32\tools\mkspiffs\0.2.3\mkspiffs.exe

• DHT11/DHT22 Sensor: Connect to pin 14 on ESP32 (can be changed in WakeDHT.ino)
• ESP32: Any ESP32 board with Wi-Fi and SPIFFS (tested on ESP32-S2 mini)
• Jumper wires, 5 kΩ resistor and breadboard: For circuit connections (or just solder everything and skip the breadboard)

Below, you can find the schematic and an example using DHT11 and ESP32-S2 mini:

git clone https://github.com/DynoW/WakeDHT.git

1. Install Arduino CLI

2. Initialize config and add Espressif package index:

arduino-cli config init
arduino-cli config set board_manager.additional_urls "https://espressif.github.io/arduino-esp32/package_esp32_index.json"

1. Update indexes and install ESP32 core:

arduino-cli core update-index
arduino-cli core install esp32:esp32
arduino-cli core list

1. Install required libraries (includes dependencies):

arduino-cli lib update-index
arduino-cli lib install "SimpleDHT"
arduino-cli lib list

1. Update the secrets.h file with your Wi-Fi details:

const char *ssid = "<YOUR_SSID>";
const char *password = "<YOUR_PASSWORD>";

Edit the computers array in data/script.js:

const computers = [
  { name: 'device1', mac: 'AA-BB-CC-DD-EE-00', ip: '192.168.1.100', port: 22 },
  { name: 'device2', mac: 'AA-BB-CC-DD-EE-01', ip: '192.168.1.101', port: 22 }
];

1. Verify board FQBN and connected port:

arduino-cli board listall | grep esp32   # find available FQBNs for your board
arduino-cli board list                           # shows connected ports (e.g. /dev/ttyUSB0 or COM9)

1. Compile and upload firmware (replace and ):

# Compile
arduino-cli compile --fqbn <FQBN> ./WakeDHT

# Upload
arduino-cli upload -p <PORT> --fqbn <FQBN> ./WakeDHT

1. SPIFFS / web files upload (mkspiffs + esptool)

• Generate spiffs image from data/:

# Navigate to project directory
cd "C:\Users\YourName\Projects\WakeDHT"

# Generate SPIFFS image
C:\Users\YourName\AppData\Local\Arduino15\packages\esp32\tools\mkspiffs\0.2.3\mkspiffs.exe -c data -b 4096 -p 256 -s 0x160000 spiffs.bin

# Upload SPIFFS to board (note: use default-reset and hard-reset with hyphens)
C:\Users\YourName\AppData\Local\Arduino15\packages\esp32\tools\esptool_py\5.0.0\esptool.exe --chip esp32s2 --port COM9 --baud 921600 --before default-reset --after hard-reset write-flash -z 0x290000 spiffs.bin

(You can use the mkspiffs and esptool executables included with your platform package or download them separately.)

Notes:

• Replace paths, and with values from your system. For Windows use COM ports (e.g. COM9).

• You can check my commands explained here

1. Serial Monitor: Check connection status and IP address
2. Web Interface:

• mDNS: http://esp32.local (may not work on all networks but easier)
• Local IP: http://192.168.1.XXX (check serial monitor or your router's admin dashboard)

The ESP32 provides RESTful API endpoints:

• GET /api - Temperature and humidity data

  {"temperature":25,"humidity":60,"valid":true}

• GET /ping?ip=192.168.1.100 - Check computer status

  {"online":true}

• GET /wol?mac=AA-BB-CC-DD-EE-FF - Wake computer

  {"success":true}

In the data/script.js you can edit the

const DEV_MODE = false;

and install the Live Server, Visual Studio Code extension, to run the app with the live api from the ESP32

1. Upload Failed / Port Not Found

• Check USB cable and drivers
• Press BOOT button during upload (if required)
• Try different baud rate: 115200

2. WiFi Connection Issues

• Verify secrets.h credentials
• Check 2.4GHz network (ESP32 doesn't support 5GHz)
• Monitor serial output for connection status

3. Sensor Reading Issues

• Check DHT11/DHT22 wiring
• Verify pin assignment (default: pin 14)
• Replace sensor if consistently invalid

4. Web Interface Not Loading

• Check SPIFFS upload was successful
• Verify file paths in data/ folder
• Check browser console for errors

5. Computer Detection/WOL Issues

• Ensure computers are on same network
• Verify MAC addresses and IP addresses
• Check firewall settings on target computers
• Enable Wake-on-LAN in BIOS/UEFI

WakeDHT/
├── WakeDHT.ino       # Main firmware code
├── secrets.h                # WiFi credentials (create this)
├── data/                      # Web interface files
│   ├── index.html       # Main UI
│   ├── script.js            # JavaScript functionality
│   ├── favicon.svg      # Icon
│   └── manifest.json   # PWA manifest
├── photos/                   # Documentation images
├── LICENSE              # License file
└── README.m          # This file

The author and maintainer of this app is DynoW contact@stefan.is-a.dev.

Based on previous work of Winlin winlin@vip.126.com, the author of SimpleDHT library.

1. adafruit/DHT-sensor-library
2. Arduino #4469: Add SimpleDHT library.
3. DHT11 datasheet and protocol.
4. DHT22 datasheet and protocol.

This app is licensed under MIT license.