The Bluetooth Open Altimeter (BTOA) is a tiny device designed primarily for logging altitude, g forces and other data in an RC airplane or as a small standalone audio vario that is also compatible with XCSoar for hang gliding and paragliding. 

This Arduino Compatible device can be re-tasked for other purposes, for instance I use it to run full colored programmable LED strips for night flying, hula hooping or other night time fun all remote controlled over the Bluetooth connection from an Android app!

In its primary role, The BTOA helps Discus Launch Glider (DLG) pilots practice launch technique by reading out the last launch altitude as the pilot lands the airplane and also acts as a battery monitor.

Specifications and Features
  • RN-42 Bluetooth module
  • LIS 331 G-sensor (+-24g 3-axis)
  • 8M onboard memory
  • Onboard USB
  • Second voltage monitor input
  • General purpose port (for GPS or anything else you like)
  • MS5611 pressure sensor which is more sensitive (10cm resolution) and less noisy than a BMP085
  • Download data and change settings over Bluetooth
  • All functionality of the classic OA
  • Weighing in at 8g
  • A small physical size of 5/8" X 1 7/8".
The BTOA RCGroups thread can be found here:
For more information or to contact me, please email

Thank you