This shield uses a DHT12 to measure temperature and humidity. Digital data transfer takes place via the I2C bus. The DHT12 allows temperature measurements of -20 to 60°C (± 0.5°C). The humidity can be measured from 20-95% RH (± 5% RH). The DHT12 is connected to the I2C bus on pin D1 (SCL) and D2 (SDA).