Gym-Link?

[SunsetRunner]

I just recently purchased the "Charge HR" product.  I particularly think it's cool that the android FitBit app seems to be able to show an almost real-time update of the metrics being fed by the device!  One of the reasons I was shopping for a heartrate monitor capable device is that my Polar chest strap unit began to die, and they do not contain user replaceable batteries.

So the problem:

I used the Polar chest strap heavily in combination with a rowing machine that would adjust resistance in order to maintain a target heart-rate.  It's a fine machine, but older, and uses Polar's "Gym Link" 5kHz signals.  It does not seem that the Charge HR transmits these frequencies.

Regardless, I am a developer by trade, and electronics hobbyist on the side, and wondered if it would be possible to read the data from the fitbit, then build out a transmitter that took that data and fed it to the rowing machine.  I can't seem to find any third party products that can do this, and I'm having a dilly of a time figuring out where to get at the real-time data.

Any chance to development of any sort in a device that converts these signals, or is the FitBit never going to be able to be used with GymLink machines?

[SunsetRunner]

Fitbit only provides an open API for 3rd party developers to use. That means only already sync'd data is available from the Fitbit servers. There is no way to obtain any direct data from the trackers themselves, at least none that Fitbit will provide. It is proprietary information.

[SunsetRunner]

Drat! I had such high hopes for this gizmo. Back to the store it goes.

[SunsetRunner]

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@SunsetRunner wrote:
Drat! I had such high hopes for this gizmo. Back to the store it goes.

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No one else's trackers alow direct access either.

[thebossman]

no device allows direct access to that information?

I am looking to look at heart rate in real time using a common consumer electronic like fitbit, we got tired of the research grade stuff, this wont be possible?

[Michael]

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@thebossman wrote:

no device allows direct access to that information?

I am looking to look at heart rate in real time using a common consumer electronic like fitbit, we got tired of the research grade stuff, this wont be possible?

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@thebossman No, Fitbit has not announced any plans to allow direct/real time access to their trackers. Their API only allows access to data synced on to their servers. You certainly can add, or vote for, it in the Feature Request forum.

[Doug]

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@thebossman wrote:

no device allows direct access to that information?

I am looking to look at heart rate in real time using a common consumer electronic like fitbit, we got tired of the research grade stuff, this wont be possible?

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I think that should be qualified to say no FITBIT device allows direct access to that information.  While it uses BLE as the actual radio carrier, it uses proprietary protocols for the data payloads.  Perhaps that is because it exchanges so much more data than using standard BLE profile support would permit efficiently.  Or maybe they designed their protocols before the various BLE profiles were finalized.

I don't know of any BLE to Gymlink repeaters out there.  I think there are a few BLE to ANT+ gateways, but I've never seen a BLE to Gymlink.  I used the Polar H7 until my second one died (the radio, not the battery).  I ended up switching to the Mio wrist based monitors.  Sadly, they don't support Gymlink though.

What I'm more disappointed in though is that it seems recent gym equipment has not added support for BLE sensors.  My local gym just replaced all their treadmills, and I was hoping the new ones would have BLE support.  Sadly, they still only support Gymlink, as does their rowers.

If interested though, you should check out the various official BLE profiles such as the Heart Rate Profile.  Docs are available here and should work with a number of consumer grade HRM devices such as those from Polar, Wahoo, Mio, etc.  If you think you can develop a box to rebroadcast the BLE to Gymlink equipment, you may want to consider a Kickstart or similar project.

I'd back you.  🙂

[JeremiahFitbit]

Please see https://community.fitbit.com/t5/Web-API/Where-is-the-Bluetooth-SDK-Can-my-app-communicate-directly-w...

[ElectroLund]

Doug, thanks for the technical post.  Answered all my questions.  This is disappointing news, but sounds indicative of the market and fickle communications layer standards, not necessarily of Fitbit's decisions.  Still, dang!

[TSnor]

NECRO ALERT.   Just adding this information for others browsing the forum.  OP is long gone.

(1)  Battery replace is very easy on the uncoded and coded Gymlink belts.  See you tube for videos.    

(2) If you want to use a newer monitor that sends ANT+ and/or BTLE then you could look at skipping gymlink completely.  Some of the older gymlink equipped devices (like my lifecycle R7i) used a separate Polar sourced receive module that plugs into their electronic.  If you want to make a bridge to your  "rowing machine that would adjust resistance in order to maintain a target heart-rate." open it up, find the receive module, put a scope on the signal path between the model and your rower.   Then build a bridge that bridges ANT+ or BTLE to your rower replacing the gymlink module at the connector on the rowers circuit board.