These days USB sticks are available for all kinds of applications, ranging from the storage of data to the measurement of temperature. However, USB sticks to measure barometric pressure are still quite rare. The USB barometric pressure sensor described in the May 2013 edition of Elektor magazine uses a Bosch sensor to measure and log the air pressure and temperature. This data can be displayed graphically and stored using Windows software.
The pressure sensor used in the circuit, a Bosch BMP085, has already been calibrated at the factory. The calibration values are stored in the BMP085 and have to be read out first, before making even the first serious measurement. This is then followed by a calculation, using the measured value and the calibration values, before arriving at a sensible result. The ‘awkward’ calculations are accommodated in a DLL, so that even the do-it-yourself programmer can easily build their own application around this barometric pressure sensor. Naturally, all the necessary routines are also accommodated in the accompanying applications for the measurement and logging of barometric pressure and temperature.
A small circuit board was designed for this project, which fits exactly in a standard USB enclosure. This circuit board has been designed in such a way that it is suitable for two different types of sensors from Bosch (BMP085 and BMP180).
This project includes a relatively comprehensive Windows program that displays the measurement results (barometric pressure and temperature) graphically. The measuring interval can be adjusted and daily measurements can also be stored in a file. Software is available free of charge from the Elektor website.
The completely assembled and tested BaroStick module (including the enclosure) is now available from Elektor at a discounted price. You take advantage of no less than 10% discount!