Configuring the On-Board Barometer When Unlocked
Written by Fezile Mojapelo
Updated at March 14th, 2026
Table of Contents
Note
Full Ground Mode configuration needs to be unlocked via async message in order to access these features.
The Griffin Air features Barometer Mode. This allows the user to configure periodic pressure measurements, configure alerts based on pressure level changes and set up Ground Mode which is an advanced flight detection mechanism that is useful for tracking assets shipped by air transportation.
Because the housing of the Griffin-Air features a gore vent, the internal pressure of the sealed housing will be equalized with the environmental pressure outside the housing.
Configuration
Trigger Setup
The barometer can be configured to perform specific actions based on a pre-configured trigger. There are 3 main barometer modes to do this. The selected mode is used in conjunction with a configurable pressure threshold to configure conditions for a pressure trigger.
Absolute: The trigger evaluates the current pressure against a known pressure level. This is used in cases where you know exactly what the atmospheric pressure needs to be to set off the trigger. You can set this High or Low, depending on whether you are interested in detecting periods of increased pressure or decreased pressure.
Delta: The trigger is set for changes in pressure that exceed a certain level. Setting this to ‘High’ allows you to detect pressure changes that increases more than a specific level over the configured period. Setting this to ‘Low’ allows you to detect pressure changes that decrease more than a specific level over the configured period. The trigger is cleared once the infraction stops, regardless of the final pressure attained.
Relative: The trigger is set similarly to the delta trigger, but the trigger is not cleared after the infraction has ended. After either increasing or decreasing beyond the configured threshold, the pressure needs to change by the same amount in the opposite direction in order to clear the trigger.
The Barometer Mode dropdown can be accessed through 'Add Parameter' in the ‘Edit System Parameter’ menu.
Active Level: The default value of ‘Outside Threshold’ means that the trigger will be true for conditions described by the green areas in the illustrations above. By setting this to ‘Within Threshold’, the red and green areas above would be swapped.
Pressure Threshold: This is measured in hectopascals and should be set depending on the mode. If the mode is Absolute, the value must be an atmospheric pressure (e.g. 1000hPa at sea level). For the other modes, this value must be a differential pressured (e.g. 20hPa to detect a change of 20hPa in the atmospheric pressure, whatever it might be).
Hysteresis: The hysteresis is always specified as a differential pressure (e.g. 10hPa). It does not need to be set to a non-zero value. The purpose of it is to reduce frequent triggering for pressures that linger around the threshold value. The hysteresis value affects the value of the threshold upon de-trigger. How it does so is described in the illustrations above.
Debounce Time: As with the hysteresis, the debounce time is used to prevent frequent triggering for pressure changes that linger around the threshold value. Once triggered, the device will suppress reporting the trigger for this period of time. After the period has elapsed, it will check if the trigger is still valid before reporting it. The value should be short if you are expecting rapid transients that should be valid triggers, otherwise it can be set to a longer value if you are expecting nuisance fluctuations around the trigger threshold.
Recalibration Period: This does not apply to the Absolute mode. This value sets a timer for re-zeroing the differential pressure reference and it is imperative that it is set correctly. As per the illustrations above, the differential thresholds are evaluated according to this time period. Hence, a valid pressure change needs to occur within this period of time to set or unset the trigger. This should be set based on testing for the specific application. It is not recommended to disable this for the differential modes, as the reference pressure is never recalibrated, so the differential pressure will be evaluated according to the pressure measured at device bootup.
Log on Calibration Period: This does not apply to the Absolute mode. This is useful for initial pressure profiling and testing, as it allows you to capture the current pressure value at regular intervals.
Periodic Capture
The barometer can also be used to capture the pressure periodically and save it to the configured Analogue Input. This can be useful for profiling the pressure of an environment. It is possible to capture the pressure periodically while also arming the device for a specific pressure trigger.
Barometer Mode for Periodic Capture
The Barometer Mode needs to be set to an option other than ‘Disabled’ in order to be used for periodic pressure capture, even if you don't actively require specific triggers. For example, you could set it to ‘Absolute Low’ and leave the thresholds at 0.
Analogue Input: Use this parameter to determine which Analogue Input you would like the pressure to be captured in. The pressure is captured in units of one sixteenth of a hectopascal. Therefore, Actual Pressure (hPa) = Analogue Input Value / 160
Capture Period: This parameter is used to determine the rate at which the pressure is saved to the Analogue Input. This is independent of the ‘Log on Calibration Period’ parameter and applied for all non-disabled barometer modes.
