ANT Forum

Hello everyone,

I am trying to implement a Python code using open-ant for getting torque and forces from Powertap P1 pedals via a USB ANT stick.

I open this topic because I think I will have a lot of questions. I have already succeed to get heart rate from a Garmin heart rate monitor using my usb stick and open-ant lib. But I am discovering that the PWR and CTF profile is way more complicated.

-Does anyone has already implemented the profile in Python?
-When I check the pedals with my phone and Android ANT Plugin manager, I have no CTF, no power, and only the RPM of the pedals. It seems also that the Auto Zero and the calibration messages does not work.

Thank you very much!
Best,
Benoît      

No one here can help me with PWR and CTF profile implementation?

I am now able to read 0x10 power message, with cadence only.
I want the torque and force on each pedal.
- I suppose I have to send calibration or autozero message first from making start the pedals to send CTF message pages?
- For sending the autozero message do I need to create a new channel, or the bidirectional receive created for simple power message is ok?

Thank you in advance...
     

...a little up please.

Why do I have only 0x10 pages with my Powertap P1?      

- I only get 0x10 pages
- Sending a 0x01 acknowledged message with 0xAA for calibration gets no answer from the power sensor.
- I have with the 0x10 pages also 0xF0 page number, what is it? I can't find the information in the Bike Power profile.

Is this forum dead or am I asking something stupid? No answer...      

Hi Benoît,

This indicates that the sensor only supports sending the power only main data page, that it may not support calibration (although I would try sending that message as a broadcast instead, just in case), and that pages 0xF0 to 0xFF are Manufacturer Specific data pages as defined in the ANT+ Common Data Pages document.

You will have to contact the manufacturer for details on how to decode their manufacturer specific data page, but for the rest of the device you only need to decode the power only data page.      

Thank you Harrison for your answer.
So finally I succeed to get calibration OK, with successful message.

For the manufacturer 0xF0 page, Powertap does not reply to my questions regarding decoding this message.

For the data, I really need the forces or torques. The Powertap P1 are supposed to be the most advanced force pedals, and I would have only power message?... :(      

Ok, so I finally succeeded to have an answer from Powertap.
The pedals does not emit Torque and Pedal smoothness data pages...only 0x10 power messages. So we have really expensive force sensors, but we can only get the cadence and the power.
Maybe there will be an update later.