Hardware: ESP32 development board, DS18B20 probe on GPIO 4, and a 128 x 64 SSD1306 OLED on GPIO 21 (SDA) and GPIO 22 (SCL), address 0x3C. The USB-powered electronics are housed in a 3D-printed enclosure.

The sensor updates about every two seconds. Cloud uploads and dashboard refreshes each run about every ten seconds. Local monitoring continues during an internet outage; missed readings are not backfilled.

First-time setup uses the temporary GeyserMonitor-XXXX network and captive portal at 192.168.4.1. After joining home Wi-Fi, use geyser.local or the assigned IP address. Local Settings provides Restart Device, Change Wi-Fi and Reset Wi-Fi Settings. Restarting keeps saved Wi-Fi.

The project links provide the full build story, code excerpts and references, plus the dashboard with its labelled example preview. The complete application repository remains private.

This is a personal temperature monitor, not a heater controller or safety thermostat. Customer accounts and offline logging are future work. Made in Pakistan.