Vassilis’ Projects

Paparazzi drivers for the EagleTree Airspeed and Altimeter sensors

The archive below will allow you to send the airspeed and altitude data from the EagleTree sensors through the telemetry stream to the ground station. At this point these measurements are simply logged and not used. The next step is to modify the airborne code to make use of these measurements (e.g. maintain constant airspeed by controlling the throttle).

The code has been tested with Version 3 of the EagleTree sensors, earlier versions might work but have not been tested. Also the coefficients for converting the raw readings from the sensors to the actual airspeed and altitude have been experimentally calculated (by comparing the readings with GPS data). Improvements will be made that will increase the accuracy of those readings.

The archive contains only the modified/new source files, copy to the appropriate directories and rebuild Paparazzi (type ‘make’ in the Paparazzi directory). This is needed because a new set of telemetry messages have been added to support the new sensors (ETS_AIRSPEED, ETS_ALTIMETER). Your airframe file will also need to be modified, I included a reference airframe file, you will need to add the lines in the section of the makefile called (‘Custom ETS modules’). If you only have one of the sensors then remove the corresponding definitions from the airframe file. After you rebuild the GCS and airborne code, open the Messages window and you should be able to see the values coming back from the sensors. If all you get is zeros then there may be something wrong with the I2C connection to the sensors.

To connect the sensors to the TWOG/Tiny boards, simply connect the four wire cable of the sensors to the I2C port of the board. The color coding is the following:

• Red wire: 5V
• White wire: Ground
• Yellow wire: SDA
• Brown wire: SCL

Downloads:

Note: The latest version of the drivers can be found in the Paparazzi SVN page.

ETS sensor drivers – September 7, 2009

EasyStar airframe configuration file (using rudder for roll)