Reading Garmin HRM-Run

Username		Password		Remember Me?	forgot password?

09 August 2019 08:47 AM

AngelaSafetyn Newbie

Total Posts: 5

Joined 2019-02-07

Hello,

I am trying, and failing so far, to read data from a Garmin HRM-Run chest strap. The site for the product (https://buy.garmin.com/en-GB/GB/p/530376#specs) indicates that it does support ANT+ heart rate.

My code uses the Linux SDK and reads well data from other HRM ANT+ devices such as the Scosche Rhythm+, Wahoo Tickr Fit or Polar OH1. However, with the HRM-Run, I try to open a channel with a wildcard device number but nothing is found.

I know that it's not a faulty hardware because a Garmin watch instantly recognizes the sensor.
I've wondered if it could come from the fact that the device has a extended number (245361). But I don't see how this wouldn't work with a wildcard.
I've also tried to open a background scanning channel - not quite sure about my implementation, but nothing showed up with that either.
At the moment, I don't really have other ideas about where the problem could come from.

Any help would be welcome. Thank you.

12 August 2019 10:31 AM #1

haighi Administrator

Total Posts: 370

Joined 2012-06-27

PM

Hi Angela,

The HRM-Run does implement the ANT+ HR profile, so it should be detected by your code that is functioning with the other HRM devices.

Are you wearing the strap while testing, or just having it sit on a desk? The strap will not transmit all the time, only when it detects it is being worn and that there is a heart rate.

Have you tried using SimulANT+ to confirm the channel parameters and that the Garmin HRM is transmitting?

Can you confirm that it is the HR profile only that you are trying to connect to, not the HR-RD profile.

Thanks,
Ian

Signature

Ian Haigh

20 August 2019 05:44 AM #2

AngelaSafetyn Newbie

Total Posts: 5

Joined 2019-02-07

PM

Hi @haighi, and thank you for your answer.

I was indeed wearing the chest strap during testing, so that's not the problem.

Thanks to your suggestion, I have tried wearing the strap with SimulANT+ by simulating a Heart Rate display and I do receive data. I didn't have to modify any parameter.

I also confirm that I use HR profile (code 120).

I still have the same problem, my code, looking for any device number matching this profile, finds other sensors but does not find the chest strap. Any further help would be much appreciated. Thank you.

20 August 2019 08:51 AM #3

haighi Administrator

Total Posts: 370

Joined 2012-06-27

PM

Can you share what you are setting the channel id to (ANT_SetChannelId)? You should be setting the transmission type to 0 (see table 5-1 in the profile document). The HRM-Run has a transmission type of 5, but most HRM's have a transmission type of 1. If you are setting as 1 in your configuration of the channel, the HRM-Run will not be found.

Ian

Signature

Ian Haigh

20 August 2019 10:50 AM #4

AngelaSafetyn Newbie

Total Posts: 5

Joined 2019-02-07

PM

Thank you, that was absolutely the case! I had not noted that the HRM demo code given in the Linux SDK set the transmission type to 1 instead of 0. (I think I understand now that this is due to the extended device number.)

Anyway, thank you very much for your help @haighi!

20 August 2019 10:55 AM #5

haighi Administrator

Total Posts: 370

Joined 2012-06-27

PM

This is not related to the extended device number. The transmission type upper nibble must be set to 0 to correctly handle extended device numbers when searching.

The lower nibble is used to indicate the channel type, and global page use. See table 5-2 in the ANT Message Protocol and Usage document for the details.

The lower nibble should always be 0 for a search to handle cases like this where it may not match.

Signature

Ian Haigh

ANT Forum