A low-cost audio-only variometer which is fully open hardware/source and Arduino compatible. It uses a MS5637 pressure sensor in combination with Linear Regression to estimate the current climb rate. All the computations are done on an Atmel Attiny88. The CR2450 battery should last a whole season...
You can build it on your own or buy it in our shop and modify it as you like.
Press the button until you here a short beep. Release the button within in 1 second and Tweety turns on. You will here the welcome sound, followed by 0.5 sec pause and the battery state:
- 2 beeps: Battery is good
- 1 beep: Battery is okay
- no beep: You should consider changing the battery
Press the button until you hear the bye sound. Release the button.
Tweety will shutdown itself if in the past 30 min all climb rate were within -0.8 m/s to 0.8 m/s.
The sink tone can be switched on or off. Remove the battery. Press and hold the button while re-inserting the coin cell. Release the button.
- 2 beeps: Sink tone on
- 1 beep: Sink tone off
A short press changes the settings. Use long press (4 sec.) to store the setting and to enter the normal operation mode again.
See climb.h
- Climb threshold: > 0.3m/s
- Sink threshold: < -2.5m/s
- Averaging interval: 1.5 sec
If you want to change those settings or change the vario tone profile (piezo.c), you need to recompile and upload the sources.