I made a firmware module for the DHT11 sensor, which measures air (relative) humidity and temperature. It’s the same as the DHT22 firmware, except for some lines when transforming sensor data to temperature and humidity.
The DHT11 is a cheaper version of the DHT22, same shape and pinout. It is slower, and the ranges are smaller, but I think it is still useful. A short comparison here in Adafruit; and here a more detailed insight by Robert Smith. I copy a part of the former here, for convenience:
DHT11 Ultra low cost 3 to 5V power and I/O 2.5mA max current use during conversion (while requesting data) Good for 20-80% humidity readings with 5% accuracy Good for 0-50°C temperature readings ±2°C accuracy No more than 1 Hz sampling rate (once every second) Body size 15.5mm x 12mm x 5.5mm 4 pins with 0.1" spacing DHT22 Low cost 3 to 5V power and I/O 2.5mA max current use during conversion (while requesting data) Good for 0-100% humidity readings with 2-5% accuracy Good for -40 to 125°C temperature readings ±0.5°C accuracy No more than 0.5 Hz sampling rate (once every 2 seconds) Body size 15.1mm x 25mm x 7.7mm 4 pins with 0.1" spacing
Code in Github . I don’t know if there is something like a fork request . It is tested alone and also with the rest of the modules.