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🌡️ Tempy

Tempy Screenshot

Push readings from my DS18B20 temperature probes into MQTT. Runs on a ESP8266 board. Has a web interface to monitor current temperatures and supports OTA updates. Originally based on fridgy-temp.

Why build this?

There are things like ESPHome that does this. But I wanted to tinker with ESP8266 boards plus learn to see how far everything has evolved since my automated pet feeder 10+ years ago.


Currently, configuration / options like Wifi and MQTT connection settings are housed in an included header file secrets.h. An example file is available secrets_build.h.

Key Description
mqtt_server Hostname of the MQTT server
mqtt_user Username for the MQTT connection
mqtt_pass Password for the MQTT connection
topic_root Topic root for tempy with an ending slash. tempy/ is what I use
wifi_SSID SSID of the Wifi Network
wifi_password Wifi network key / password
update_username For OTA updates, the username
update_password For OTA updates, the password

MQTT Topics

If using Home Assistant, Tempy publishes MQTT Discovery data upon boot. If enabled in Home Assistant, this will create temperature sensors in Home Assistant with the name sensor.{probe id}. From there, you can rename and change the entity id to something more meaningful.

If manually configuring:

Purpose Topic Notes
State Topic {topic_root}/{probe_id} Raw readings will be in Celsius
Last Will and Testament {topic_root}/{chip_id}/lwt ONLINE / OFFLINE for values
Home Assistant Discovery homeassistant/sensor/{probe_id}/config

HTTP Server

Two routes exist:

  • / - Web interface to view currently detected probes
  • /update - OTA updates. Will require HTTP authentication using the credentials from the options above.


This is a hobby project. The OTA updater does not validate the firmware is from a trusted source. The HTTP server does not support TLS potentially exposing the OTA credentials. MQTT connection does not support TLS either.

Ideally, put these on an isolated network with very limited connectivity.


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