This is 3 in 1 digital data logger project. You can take several measurements: Temperature, Humidity, and Barometric pressure measurements. The project use AVR ATmega8 as main processor. While humidity and temperature are sense by Sensirion SHT75 and the barometer use Intersema MS5534. Those two components talk their own language which is similar to other Serial synchronous protocol (or SPI).
Sylvain Bissonnette said that all measurements have their own dedicated A/D converter in each sensor. This digital environment sensor No Need any calibration. Besides 3 measurement function and no Calibration, this data acquisition projects also features RS485 interface and Network firmware upgradeable.
3in1 Data logger
Project Documentation and Schematic