ANT Forum

Hello,

Hopefully someone can advise. I want to record or transmit the actual / instantaneous power or torque at a given crank position - similar to the Watt Bike polar profile.

Ideally I would measure the crank position and use each pulse as an event, for example every 45 degrees of rotation or less, but unless I have misread the device profiles ANT+ only allows me an event / tick every full resolution?

Is there a way around this limitation?

Thanks

V      

Hi V,

While the profile is written to expect updates for every full revolution for event based power meters, this does not mean you cannot base your events on partial crank positions instead. For instance, in the crank torque data page, your update event counter would increment for the new event, the crank ticks may or may not go up, but the instantaneous cadence, accumulated period, and accumulated torque would go up.

Best regards      

Thanks Harrison.

How would I format the crank position and power or torque in a way a compatible ANT+ device from a third party device would understand. For example a Garmin Edge 520 / 1000 or similar would read the data and know the crank is at say 145 deg and 220w produced, 150 deg 230 produced and so on?



     

At this time, the ANT+ Bike Power Profile does not support transmitting the actual angle from the sensor, you would have to add this field as a manufacturer specific data page and then decode it on the Edge using Connect IQ.

More information regarding developments around this type of data to be added to the base profile is available to members of the ANT+ Bike Power Technical Working Group/ANT+ Alliance.      

Would it be possible for anyone to add a manufacturer specific page or does this require approval? Could I develop a specific page that would automatically be recognised when I become a full member?

I'm interested in becoming a full member but it's a bit chicken and egg, until I have completed the prototype unit I'm not in a position to fund the membership fee.      

Manufacturer specific pages may pass through certification without specific approval as long as the specifications surrounding page transmission pattern are followed. You may also use the "development" manufacturer ID to pass through certification without becoming a member, although it may make it harder for displays to recognize the brand of the sensor.

Correct, becoming a full member would allow you to join the TWG and provide input for pages and data fields to be added to the profile, as well as request a manufacturer ID. I can't guarantee all manufacturer's would update their displays to support new pages, but at least the leading displays tend to support as much data as possible.

https://www.thisisant.com/developer/resources/tech-bulletin/manufacturer-id      

Thanks that is really helpful