Measurement and control of temperature and relative humidity finds applications in numerous areas. These days devices are available which have both temperature and humidity sensors with signal conditioning, ADC, calibration and communication interface all built inside them. The use of such smart sensors greatly simplify the design and reduces the overall cost. While mikroElektronika provides modules for SHT1x sensors which provide accurate measurements of temperature and humidity in digital format, they are still expensive for hobbyists use. This articles discusses the DHT11 sensor which also provides calibrated digital outputs for temperature and humidity but is relatively lot cheaper than the Sensirion sensors. The DHT11 sensor uses a proprietary 1-wire protocol which is implemented here with the PIC16F887 microcontroller to receive the temperature and humidity values from the sensor and display them on a 16×2 character LCD. The code has been tested with UNI-DS6 development board.

For full description of the DHT11 protocol and its implementation, visit: Understanding DHT11 protocol

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