Bluetooth temperature and humidity logger based on ESP32 and Smartphone

An ESP32-based Bluetooth temperature and humidity logger that is compatible with smartphones can be created by using the ESP32 as a Bluetooth Low Energy (BLE) device and implementing a temperature and humidity sensor into the system. The ESP32 can then send temperature and humidity data to a smartphone application, which can display and store the readings. To ensure compatibility with a smartphone, the ESP32 device should support the Bluetooth 4.0 or later standard, and the smartphone app should use the appropriate BLE APIs for communicating with the ESP32.