The RHT101 / DHT11 is an inexpensive humidity sensor compared with other humidity sensor offerings. MaxDetect, the maker of the sensor, cooked up their own 1-wire protocol, which is distinct from (and incompatible with) the Dallas 1-wire protocol. This is a very inexpensive sensor compared with other offerings, but also somewhat less accurate. The datasheet spec is +- 5% for the relative humidity.
The device is supported by Lady Ada’s DHT test library seems to work with this sensor so the protocol is about the same. We modified Lady Ada’s test sketch just a bit to accommodate just inserting the chip into an Arduino or BBB breadboard. The modified library is below.
- High precision capacitive humidity sensor
- Fully temperature compensated
- Relative humidity and temperature measurements
- Outstanding long-term stability (+-1%RH/year)
- Easy connection to microcontrollers
- 3.3 – 6V VCC
- Low power (1mA measuring, 50uA standby)
- Fully temperature compensated +-1%RH/year