The DHT11 is a low-cost digital sensor that measures ambient temperature and relative humidity. It uses a resistive humidity element and a thermistor, outputting a calibrated digital signal on a single wire.
| Supply voltage | 3.3 – 5.5 V |
| Temp range | 0 – 50 °C |
| Temp accuracy | ± 2 °C |
| Humidity range | 20 – 90 % RH |
| Humidity accuracy | ± 5 % RH |
| Sampling rate | 1 Hz max |
| Protocol | Single-wire |
| Package | 4-pin SIP |
The MCU pulls the data line low for ≥18 ms to trigger a reading, then releases it. The DHT11 responds with a 40-bit frame: 16 bits humidity integer+decimal, 16 bits temperature integer+decimal, 8-bit checksum. Most breakout boards include the required pull-up resistor.
Low accuracy compared to DHT22/SHT31. Cannot read below 0 °C. Maximum 1 reading per second. Sensitive to condensation — avoid use above 90 % RH for extended periods.