Raw pressure data

Is Garmin watching their forum? Anybody?

I would also like access to the raw pressure data as well. I suspect for the same reason - a depth gauge. At the very least a complete and accurate description of what the data we are getting out of GetSensorInfo is so we can manually deconstruct it back into what is needed. The raw info is available as a datafield, so why can we not access it in the API? (The same goes with GPS altitude)

Right now the only workaround is to use altitude (from either SensorInfo or ActivityInfo), but since we don't know how exactly how that is derived, any depth calculations base off altitude can not be considered reliable.

Thanks

I have plans to look into this further, but it'll have to go into my queue. I'll see what I can find out and try to get an answer by later this week or early next week.

This hasn't been forgotten! I'm talking to the device teams to get an answer on this. Connect IQ doesn't do anything to the data--we're basically just making a request to the OS for sensor data and piping through whatever it returns. If there is any auto-calibration or massaging of the data, it's happening at a lower level. Once I have an answer, I'll post it here. Thanks for your patience!

Thanks Brandon! I will wait patiently. I hope you will come back with good news ;)

This hasn't been forgotten!

I think it now is forgotten?

Hey guys,

This is how I do it in my app.

Data available: sensor.altitude (from pressure using baro setting) and sensor.pressure (that really gives the barometer setting adjusted with changes in pressure since that setting was made by user - as far as I understand)

Assumption: even a 100mb change in pressure (which is huge) will only impact the result by only 10cm under water, so it's quite negligible.

1/ Take current pressure altitude
2/ Convert it to ambient pressure (below, replacing p0 with baro setting would return the correct ambient pressure, but again sensor.pressure doesn't give exactly baro setting).
3/ Convert that to depth

// Physics for ambient pressure calculation
var p0 = 101325;// sea level standard atmospheric pressure Pa
var L = 0.0065;// temperature lapse rate, = g/cp*for dry air K/m
var T0 = 288.15;// sea level standard temperature 288,15 K
var g = 9.80665;// Earth-surface gravitational acceleration 9,80665 m/s²
var M = 0.0289644;// molar mass of dry air 0,0289644 kg/mol
var R = 8.31447;// universal gas constant 8,31447 J/(mol*K)
var exp = g*M/R/L;
var fact = L/T0;

var press = p0 * Math.pow((1-altitude*fact),exp)/100;
var depth = 0.0;
depth = (press/1000.0 - 1);

if (unitElevMeters){
altStr = "-" + depth.format("%.2f") + "m";
} else {//feet
altStr = "-" + (depth*3.28084).format("%1f") + "ft";
}

Don't know if it helps but I hope so.

No not forgotten. :) Work is still ongoing, but it's going to take some time. I apologize that it's not being completed more quickly. It's not a simple matter of flipping a switch to make the data available--we're coordinating with a couple of other technology teams to come up with the best solution, and that will likely require us to also coordinate with device teams to integrate any necessary changes.

@julienvn: thanks for the formula this may be very helpful. But to be honest i have some troubles to use it. Technical it is not an issue but why should i make all strange calculation to recalculate the original data? I am an engineer that has the motivation to make an app for garmin to make their prduct better for free. It take a lot of my time to do this but how is the support to me in this case? I don't understand it is now 2 months later and still no response again.

@brandon: please correct me if i see things the wrong way ��. I would be happy to admit that i am wrong in this case.

Hi there,
I had the same issue as Fruitmans and posted the same question on another thread (https://forums.garmin.com/forum/developers/connect-iq/159801-)
However, as it seems there is still no solution to that. Is there any chance that the ambient pressure sensor reading is going to be directly available? It seems kind of odd that only processed pressure data is available through the API even though there exists a datafield for this data.

Maybe Brandon can give us an update on that after two years? Are there any plans to make this available through CIQ?

Thanks for an update