DifferentialPressure (UORB message) 
c
uint64 timestamp                     # time since system start (microseconds)
uint64 timestamp_sample
uint32 device_id                     # unique device ID for the sensor that does not change between power cycles
float32 differential_pressure_pa     # differential pressure reading in Pascals (may be negative)
float32 temperature                  # Temperature provided by sensor in degrees Celsius, NAN if unknown
uint32 error_count                   # Number of errors detected by driver