Variometer firmware update

Please read before updating

Choosing version A or version B

When booting, your variometer indicates on the upper right of the display both the display size and firmware version, for example v0.36-29A or v0.36-29B. If you variometer doesn't indicate a version, please choose version A. 


  • v0.36-29A -> Firmware version A
  • v0.36-29B -> Firmware version B
  • v0.35 -> Firmware version A
  • v0.34 -> Firmware version A
If the display doesn't function correctly or doesn't work at all after updating, it means that the wrong version was flashed. Please start again with the correct version.

Changes with audio files from version 0.36:
- Audio files must be placed in a folder named "audio" at the root of the SD card.
- File "flight_start.wav" must now be named "start.wav".

Latest version: Version 0.39

Download Audio files in your prefered language. Files must be placed in a folder named audio at the root of the sd card. You can create your own files: by using the same file names. Frequency: 16kHz, format: Unsigned 8-bit PCM WAV.



  • Fix a bug with wrong UTC time in some cases
  • Fix a bug with IGC file where incorrect B records were logged  for some GPS coordinates
  • Added miles units in addition to imperial: altitude as feet, Vz as x100 feet/min, distance as miles
  •  Compatibilty with Varduino Manager v0.10 only


  • Fix a bug where Varduino Manager couldn’t see IGC files because IGC files are now in IGC folder on sd card.


  • new sd organisation with audio, igc and wp folders. Flight_start.wav is replaced with start.wav
  • waypoints radius can be set by naming the waypoint file in the following format: waypoints-Xm.wpt where X is the radius in meters (1-99999m).
  • new display implementation
  • Version check before Varduino Manager issues a command


  • Fixes bug introduced by 0.34 where variometer was sometimes crashing during voice notifications.


  • Auto turn off feature The variometer will turn off after 15 minutes if not activity is recorded. The timeout can be set in Varduino Manager or disabled
  • The bluetooth vario data can now be output to up than 10 Hz (10 times per second).  The frequency can be set in Varduino Manager. This is helpful for more accurate data if using the thermal circler in XCSoar or other features that require frequent vario data update.
  • The glide ratio will display 0 if speed is less than 5km/h, to avoid exotic values at low speed
  • Screen layout reorganization.
  • Other minor improvement.


  • Fix bug where rescue alarm settings were not imported correctly from Varduino Manager.


  • Fixes bug created by v0.30 where logging didn’t always start where no waypoint file was present.
  • Fixes bug where beginning of flight was not notified because of wrong wave file name


  • A rescue parachute alarm will now trigger when your vertical speed is too low for too long. The settings can be modified from Varduino Manager. Current settings are faster than -6m/s for longer than 10 seconds
  • Varduino can now speak. Literally*.  It’ll let you know when:
    • turning off
    • turning on
    • gps fix is acquired
    • beginning of flight is detected.
  • Varduino will not boot or shutdown when battery is too low from software instead of a hardware detection

*.wav files are needed at the root of the sd card.


  • Variometer is now louder.
  • Variometer algorithm improved and now even more sensitive
  • SD problem icon if no sd card is present or if there is a communcation problem with the sd card.
  • Fixed bug where IGC filename and IGC header year was sometimes set to 2080. Please report if you see that logging sometimes doesn’t start after this update as logging will only start with a valid date.
  • Fixed bugs where communication with varduino manager was not always reliable. You need the latest Varduino manager version for firmware 0.30 to be able to communcate with it.


  • Fixed bug where vario would not mount as mass storage device or track log would not be recorded if not waypoint file was on the sd card.
  • Fixed bug with IGC logging where latitude or longitude minutes were not incremented when 1000 seconds were reached.

v0.28: Major update: please report bugs and downgrade to 0.26 or 0.27 if needed!!

  • Waypoints navigation is now implemented. Check out this page to get started.
  • Number formating improvement. Invalid numbers now show as —
  • Imperial units improvement: Vz shows now as x100 feet/min, e.g. 460 feet/min shows as 4.6. Distance are now in KM also for imperial units.
  • Other various improvements

v0.27: Major update: please report bugs and downgrade to 0.26 if needed!!

  • Varduino now mounts on your computer as a mass storage device. This means that IGC files can be now accessed from windows explorer and that varduino manager is not needed anymore for tracklogs.
  • The ble module is configured now for android or iOS automatically. Choose either android or iOS in varduino manager for the right settings to be applied.
  • Numbers are now aligned right on the display so that they’re next to their corresponding unit.
  • Fix display bug where imperial units were displayed instead of metric.
  • Fix display bug where glide ratio was too close to distance to WP.


  • Full implementation of imperial units
  • Display layout reorganization for compatibility with imperial units


  • fix bug with IGC tracking where zeros were added when latittude or longitude were reaching 100 seconds.
  • fix bug with android bluetooth communication. Now communicates correctly with xcsoar, xctrack, flyme and other android apps.


  • When device is off, the display now automatically updates when charge is complete or when charge starts.
  • third button now turns BLE on and off.
  • Dist to WP now indicates distance to take off. Implementation of waypoint management in progress.


New vario algorithm with better sensibility and allowing compatibility with the vario profile profile customization tool in varduino manager.

New boot sequence for power management

Button 2 now changes volume (no volume + 3 different levels)


Initial release