 The DHT-11 and DHT-22 sensors were once the go-to low-cost devices for gathering temperature and humidity data. Unfortunately, they rely on a single-wire communication protocol, which can be a pain to read on the microcontroller side. Instead of pulling signal voltage low to represent a zero bit and high to send a one, these sensors first pull signal low just to indicate the start of a single bit, and then raise signal high for 28 microseconds to represent a binary zero, or 70 microseconds to represent a binary one. Without an additional wire for synchronization, your microcontroller is left counting microseconds and not doing whatever else you had in mind for your project's main loop. So for your next temperature-aware project, consider an I-squared C-enabled device like the AHT-20 or the SI-7021 here, and save the old sensors for the vintage collection.