I was in Bhutan last December, and as we travelled to different locations, I kept wondering what the temperature and altitude was, and wished I had some gizmo that would show me these values. Back home, I did a bit of research on altitude sensors, and one that came up was the cheap BMP180 sensor. It measures temperature and pressure, and the latter can be used to calculate the altitude. It’s been lying around with me the past few months, and now I’ve finally gotten around to building a display around it.
This project uses an Arduino Pro Mini 3.3 V clone, a BMP180 sensor and a Nokia 5110 LCD module to display the current temperature, altitude and pressure.
The circuit uses a push button so that the circuit and display is on only as long as you keep it pressed, conserving the battery.
For More Detail : Temperature / Altitude / Pressure Display using BMP180
French 
English