How to get wheel rpm or circumference from speed sensor?

I need to know the wheel exact circumference for my gear calculator app. ATM there is a manual data from properties. But there is the speed sensor, that have an automatic calculated wheel circumference data and that sensor have an RPM that help to calculate that number. The problem is, I did not found any way to reach those informations.

The Toybox.AntPlus.BikeSpeedInfo have only speed and distance method.

The ANT+ protocol said, the sensor must be support this datas:

Latest Speed Event Time
Cumulative Wheel Revolutions
Stopped flag indicating zero speed (optional)
Battery level (optional)
Cumulative Operating Time (optional)
Manufacturer ID and Serial Number
Hardware Version, Software Version and Model Number

Any idea how to get it?

flocsy🤠 10 days ago in reply to bunny.hu

And what is the actual one? And is that from a table? Is it written on the tyre? Did you measure with a tape?

And is the tyre pressure enough to be precise to the mm? What is your weight (including the bike and the bags)? Was it in winter on a day the temperature was -20C or a hot summer day of 40C?

bunny.hu 10 days ago in reply to flocsy🤠

The datas from the sensor auto C calculation. My list is just simple show how much its changed in a short time. Its because there was talking about how frequent recalculate the sensor and how it possible working. The actual one is a good question yes, you right, many thing can change. That's why I would prefer to recalculate from app IF i know the rotation number that I do not.

bunny.hu 10 days ago in reply to mcinner1

Right, with DI2 and one chainring is a simple life :)

flocsy🤠 10 days ago in reply to bunny.hu

But then why do you question why Garmin is recalculating every km?

First and foremost GPS is not that precise. Then you could've grab some water at a station or maybe stopped for a croissant. You could've climbed the south side of the hill, and now going down on the north side, with significantly lower temperature. You could've released air from your tubeless tyres. Or pump them. So it really couldv'e changed a bit. IF you care about the millimeters. That's why I asked you what is your "actual" measurement when you wrote "My 32/622 Vittoria tire on 3.5bar". If you don't care about the millimeters, then why did you write how the millimeters changed every few minutes?

bunny.hu 10 days ago in reply to flocsy🤠

"If you don't care about the millimeters, then why did you write how the millimeters changed every few minutes?"

Because dpawlyk wrote:

I think it calculates it early after it’s turned on. I don’t think it keeps recalculating it during the ride.

And the whole discussion is about how can whe use the speed sensor and how the Garmin using for wheel C calculation :)

mcinner1 10 days ago in reply to mcinner1

mcinner1 said:
BTW: you can measure the wheel rotations for an entire activity: mount a cadence sensor to the spokes of the wheel. In Garmin Connect you can read the sum of crank revolutions - which are now wheel revolutions.

What I forgot to point out:
You can only connect one cadence sensor to your Edge. So this method is only to find out the wheel circumference for testing purposes. (But there are more easy ways to do this )