README.md

Prometheus ESP8266 DHT Exporter

An IoT Prometheus exporter for measuring temperature and humidity, using an ESP8266 (Arduino-compatible) with a Wi-Fi module and a DHT (temperature + humidity) sensor.

Metrics

Metric	Description	Unit
iot_info	Metadata about the device.
iot_air_humidity_percent	Air humidity.	%
iot_air_temperature_celsius	Air temperature.	°C
iot_air_heat_index_celsius	Apparent air temperature, based on temperature and humidity.	°C

Requirements

Hardware

• ESP8266-based board (or some other appropriate Arduino-based board).
  • Tested with "Adafruit Feather HUZZAH ESP8266" and "WEMOS D1 Mini".
  • Tested with ESP8266 Mini from Jaycar (XC3802)
• DHT sensor.
  • Tested with Jaycar DHT11 HAT (XC3856 w/ XC3802, set DHT_PIN to 11)
  • Tested with a cheap DHT11 from eBay and "Wemos DHT Shield" (using pin 2).
  • DHT11 supports a maximum of 1Hz polling while DHT22 supports a maximum of 2Hz polling.
  • Both DHT11 and DHT22 support both 3V and 5V at 2.5mA max current.

Software

• Arduino IDE
  • Download and install.
• esp8266 library for Arduino
  • See the instructions on the page.
• DHT sensor library for ESPx
  • Install using the Arduino library manager.
  • You can also try the Adafruit one, but that one didn't work for me.

Building

Hardware

• Adafruit Feather HUZZAH ESP8266

  • Wire the DHT sensor power to the 3.3V and any GND on the ESP and wire the data output to e.g. pin 14 (aka D5).

• Jaycar ESP8266 Mini

  • Set DHT_PIN to 11
  • Set board to LOLIN(WEMOS) D1 R2 & Mini in Tools -> Board.

Software

Using the Arduino IDE.

1. Copy config.default.h to config.h and fill inn the details.
2. Open src/src.ino in the Arduino IDE.
3. Set the correct settings for the board.
   • WEMOS D1 Mini uses board "WeMoS D1 R2 & mini".
   • Adafruit Feather HUZZAH ESP8266 uses "Adafruit Feather HUZZAH ESP8266".
   • Jarcar ESP8266 Mini uses WeMoS D1 R2 & Mini
4. Build and upload using the Arduino IDE.

Version

See src/version.h.

It's set manually since no build tools (or CI) other than the Arduino IDE is used.

License

GNU General Public License version 3 (GPLv3).