Hi Alonso,
baro handling is currently still a bit different under fixedwing firmware... we are in the process of cleaning this up, but it's not done yet.
I added the baro_ms5611_spi.xml module in the baro_peripherals branch, would be great if you could test if this works.
To use it:
git remote update
git checkout baro_peripherals
Then in your airframe file:
<modules>
<load name="baro_ms5611_spi.xml">
<define name="MS5611_SPI_DEV" value="spi3"/>
<define name="MS5611_SLAVE_DEV" value="SPI_SLAVE3"/>
</load>
<load name="baro_board.xml">
<define name="BARO_ABS_EVENT" value="BaroMs5611UpdatePressure"/>
</load>
</modules>
Cheers, Felix