Need to get altitude info from barometer of pixhawk 2.1!

1

I am new to pixhawk. i am using pixhawk 2.1. i am planning to fly the drone in the chimney. For that purpose,i need to use the barometer for the altitude measurement. I am using pX4 firmware version 1.6.3. Please let me know which parameters do i need to set to get the altitude value from the barometer. I am getting pressure_alt around -79 . I don’t understand what is this value. Please let me the basic setup to get the barometer altitude working in the pixhawk. Thanks

2

So to answer your question,
You can get raw, unfiltered barometer output from the UORB topic:

#include <uORB/topics/sensor_combined.h>
sensor_combined.baro_alt_meter

This is raw barometer, unfiltered.

Alternatively, you can use the filtered GPS (or barometer, not 100% sure on this one) height from the UORB topics:

#include <uORB/topics/vehicle_global_position.h>
#include <uORB/topics/vehicle_local_position.h>

Hope this helps,