The Air Data Computer Asgard can be controlled using the specific command set documented here on the repo. Sometimes it is necessary to compensate the sensors readings for an offset. Let’s pretend we want to compensate for the offset of the differential pressure sensor. That can be accomplished by sending the command “$CCS,EXE,1,1″ through the ADCs USB or the Bluetooth interface. It will be necessary to recalibrate the unit each time the ADC is power up. That can be quickly done using a free scriptable serial terminal.

Alternatively, when we are on the field, it may be convenient to use a configuration file stored in the microSD card. The ADCs default configuration file is named “CONFIG.CFG” and is in the microSD root path. So to automatically set the offset at power on we will use a “CONFIG.CFG” file with only a line reading like “$CCS,EXE,1,1”.

It should not be appropriate to zero the differential pressure in windy conditions, think of a pitot mounted on a plane. So it can be more practical to calibrate the sensors offset indoor. In this case, we will follow those steps.

  • Issue “$CCS,EXE,1,1”  command to ADC
  • Read the reply from ADC, let it by “$CCA,1,45”, and note the offset value 45
  • Place a “CONFIG.CFG” in the microSD root, the file contains “$CCS,USE,1,1,45,,”; 45 is the offset precedently noted.

The command stored within the config file instructs the unit to use an offset value of 45 for the differential sensor readings. This latest solution relies on the low time drift of the sensor calibration.  It is necessary to repeat the operation regularly. For most uses, an offset annual calibration should be proper. Each one of the three shown procedures fits well for specific applications, in the end, the user will decide what is the most comfortable.