Discussion - Recent Threads

How to get RR intervals from FIT hr messages (Fit file message 132)?

pepe — Tue, 28 Jul 2026 18:53:16 GMT

Garmin units write RR intervals to Fit file from Garmin HRM 600 and other Garmin HRM with memory at the end of a offline activity,(like swimming) writing 11 RR intervals per message,

= TYPE=12 NAME=hr NUMBER=132
--- timestamp=1126167485=2025-09-07T08:18:05Z
--- event_timestamp=1778373632=1736693.000 s
--- fractional_timestamp=0=0.0000 s
--- filtered_bpm=71=71 bpm
--- xxx251=0=0
==
= TYPE=11 NAME=hr NUMBER=132
--- filtered_bpm=71=71 bpm,71 bpm,71 bpm,71 bpm,71 bpm,71 bpm,71 bpm,71 bpm
--- event_timestamp_12=0=0.000 s,0.031 s,0.068 s,0.214 s,0.117 s,0.206 s,0.075 s,0.108 s,0.021 s,0.022 s,0.083 s,0.135 s
==

Type‑12 Anchor Processing

timestamp (absolute Unix time) and the scalar event_timestamp (a 32‑bit integer in 1/1024‑second units).
The anchor’s absolute time is calculated as:
anchor_abs = timestamp + event_timestamp / 1024.0
This event_timestamp scalar is used as the baseline for the first beat of the subsequent Type‑11 message (if present).

Type‑11 Message Processing (The Core RR Extraction)

When a Type‑11 message is encountered, GC processes two fields:

1. Scalar `event_timestamp`

This is a 32‑bit integer representing the cumulative offset (in 1/1024 seconds) of the first beat of this message from the start of the activity (or midnight).

2. Packed `event_timestamp_12` (field 10)

This field contains 12 bytes (0–255). They are not RR intervals – they are packed 12‑bit cumulative offsets that extend the 32‑bit timestamp for the subsequent 11 beats.
Needs unpacking the bytes using a specific bit‑twiddling algorithm (overlapping pairs, alternating extraction).
For each pair of bytes, reconstruct a 12‑bit value
Result per Type‑11 Message
- 1 absolute beat time from the scalar event_timestamp.
- 11 additional absolute beat times from the unpacked bytes.
- Total: 12 absolute beat times per message.
- 11 RR intervals (differences between consecutive absolute beat times).

Fenix 6 product names in fit sdks seem to be wrong?

HermoT — Sat, 25 Jul 2026 17:41:33 GMT

Hi [mention:628ab37a8c3543ceb1f9ea2250b7c422:e9ed411860ed4f2ba0265705b8793d05]

Correct me if I am wrong, but it seems to me the fenix 6 series have the wrong names in the fit sdks.
https://github.com/garmin/fit-javascript-sdk/blob/main/src/profile.js#L24921-L24925

My belief is that the "Sport" is the regular fenix 6, and what appears to be the regular fenix 6 in the sdk should be the Pro.

I have confirmed this with a fit file from my own fenix 6 Pro.

SDK	Reality	Notes
3287: "fenix6SSport"	fenix6S
3288: "fenix6S"	fenix6SPro
3289: "fenix6Sport"	fenix6
3290: "fenix6"	fenix6Pro
3291: "fenix6x"	fenix6XPro	Based on naming convention of "S" in fenix6S, "x" should be uppercase "X"

Same most likely applies for the Asia versions too:
https://github.com/garmin/fit-javascript-sdk/blob/main/src/profile.js#L24955-L24959

Accidental duplicate post. Please delete this Discussion copy and retain the Question version.

Wilson — Wed, 22 Jul 2026 12:37:27 GMT

【Duplicate submission created accidentally. Please delete this Discussion thread. The Question version is the intended thread:

[mention:485eae30809b4318b1fa9f6831359aad:46448885d0e64133bbfbf0cd7b0fd6f7] 】

I would like to distinguish between the capacity of one FIT hrv message and the number of RR intervals delivered by a sensor in one BLE notification.

In a previous FIT SDK discussion, Ben FIT explained that the hrv.time array contains between one and five valid RR intervals, with five physical slots provided because the maximum heart rate representable in a FIT Record message is 254 bpm:

https://forums.garmin.com/developer/fit-sdk/f/discussion/255690/fit-file-hrv-data-array-interpretation/1220787

However, an incoming BLE Heart Rate Measurement notification does not necessarily represent one second of measurements and does not necessarily correspond one-to-one with a FIT hrv message.

The Bluetooth Heart Rate Service specification states that:

the RR-Interval Present flag may change during a connection;
a Heart Rate Measurement may contain no RR intervals or multiple RR intervals;
with the default 23-byte ATT MTU, one notification may contain up to eight or nine RR-Interval fields, depending on the other fields present;
the notification interval is determined by the sensor and may vary.

Specification:

https://www.bluetooth.com/wp-content/uploads/Files/Specification/HTML/HRS_v1.0/out/en/index-en.html

A valid sensor implementation may therefore send several heart-rate-only notifications and then include the accumulated RR intervals in a later notification. If it batches approximately two seconds of data, a single notification can contain more than five RR intervals when heart rate exceeds approximately 150 bpm.

My FIT-format questions are:

Is the five-value capacity only a limit of each individual FIT hrv message?
If a recording device receives six to nine RR intervals in one BLE 0x2A37 notification, is the expected FIT representation to write the first five values in one hrv message and the remaining values in one or more immediately following hrv messages?
Is it valid for multiple consecutive FIT hrv messages to originate from the same incoming BLE notification?
Since hrv messages have no independent timestamps, are the values in these consecutive messages simply interpreted as one continuous RR-interval sequence in file order?

This question was prompted by an actual Forerunner 955 activity:

Approximately 2,004 seconds / one-second Record messages
1,018 FIT hrv messages
Average spacing of approximately 1.968 seconds per hrv message
Physical capacity: 1,018 × 5 = 5,090 RR-interval slots
Valid RR intervals in the FIT file: 5,012
RR intervals in the aligned sensor-local sequence: 5,294
Difference: 282 RR intervals

If only one five-slot hrv message is written every 1.968 seconds, the maximum storage rate is:

5 × 60 / 1.968 ≈ 152.4 RR intervals per minute

This is very close to the heart-rate range above which the discrepancy becomes apparent.

In a separate low-heart-rate test, an nRF Connect log showed that the sensor sent a Heart Rate Measurement notification approximately every 700 ms but included accumulated RR intervals only about once every two seconds. All 136 RR intervals covered by that capture were present in the BLE payloads, in the correct order.

I have not yet captured the BLE payloads during the high-heart-rate portion, so I am not claiming that the FR955 has definitively discarded the missing values. I am first trying to establish the intended FIT serialization behavior.

Could the FIT team confirm whether more than five RR intervals received together should be preserved by writing multiple hrv messages, and whether that representation is supported by Garmin activity files?

How should more than five RR intervals from one BLE notification be serialized into FIT hrv messages?

Wilson — Wed, 22 Jul 2026 12:33:35 GMT

I would like to distinguish between the capacity of one FIT hrv message and the number of RR intervals delivered by a sensor in one BLE notification.

https://forums.garmin.com/developer/fit-sdk/f/discussion/255690/fit-file-hrv-data-array-interpretation/1220787

However, an incoming BLE Heart Rate Measurement notification does not necessarily represent one second of measurements and does not necessarily correspond one-to-one with a FIT hrv message.

The Bluetooth Heart Rate Service specification states that:

the RR-Interval Present flag may change during a connection;
a Heart Rate Measurement may contain no RR intervals or multiple RR intervals;
with the default 23-byte ATT MTU, one notification may contain up to eight or nine RR-Interval fields, depending on the other fields present;
the notification interval is determined by the sensor and may vary.

Specification:

https://www.bluetooth.com/wp-content/uploads/Files/Specification/HTML/HRS_v1.0/out/en/index-en.html

My FIT-format questions are:

Is the five-value capacity only a limit of each individual FIT hrv message?
If a recording device receives six to nine RR intervals in one BLE 0x2A37 notification, is the expected FIT representation to write the first five values in one hrv message and the remaining values in one or more immediately following hrv messages?
Is it valid for multiple consecutive FIT hrv messages to originate from the same incoming BLE notification?
Since hrv messages have no independent timestamps, are the values in these consecutive messages simply interpreted as one continuous RR-interval sequence in file order?

This question was prompted by an actual Forerunner 955 activity:

Approximately 2,004 seconds / one-second Record messages
1,018 FIT hrv messages
Average spacing of approximately 1.968 seconds per hrv message
Physical capacity: 1,018 × 5 = 5,090 RR-interval slots
Valid RR intervals in the FIT file: 5,012
RR intervals in the aligned sensor-local sequence: 5,294
Difference: 282 RR intervals

If only one five-slot hrv message is written every 1.968 seconds, the maximum storage rate is:

5 × 60 / 1.968 ≈ 152.4 RR intervals per minute

This is very close to the heart-rate range above which the discrepancy becomes apparent.

Developer onboarding blocked

Noah — Wed, 29 Apr 2026 13:19:37 GMT

I have emailed connect-support@developer.garmin.commultiple times with no response. The developer onboarding form has been down for more than a month. Has anyone had any success recently onboarding to the developer account or getting access to the activity API?

RE: Developer onboarding blocked

Nick — Fri, 17 Jul 2026 09:51:23 GMT

I received a response, saying that they are no longer processing applications for the developer program, because of changes or something. Not much help, I'm afraid?

Sending HR Data from Samsung GW5 to Edge 530

Former Member — Thu, 16 Jul 2026 16:52:15 GMT

Hey All,

I've wrote an app for my Samsung Galaxy Watch 5 Pro and trying to connect it to Garmin Edge 530. I can see watch is showing up as HR Sensor on the list but I couldn't get it to actually send data to my Edge 530. Interesting thing is, I tried other devices and code seems to be fine, I can connect and transmit HR data. But when it comes to establishing connection to my Edge 530, it doesn't work.

Could anyone help me debug/resolve this issue ?

Thank you.

RE: Redistribution of the Garmin FIT Java Library

3861945 — Wed, 15 Jul 2026 06:31:12 GMT

Thank you for the clarification.

To confirm specifically:

May a commercial software vendor redistribute the unmodified Garmin FIT Java SDK binary (com.garmin:fit JAR) as part of its commercial end-user application installer, provided the SDK is only used internally by the application and is not exposed as a separate SDK or developer tool?

Redistribution of the Garmin FIT Java Library

3861945 — Mon, 13 Jul 2026 05:23:06 GMT

Hello Garmin FIT SDK Team,

I have a question regarding the redistribution of the official Garmin FIT Java SDK.

The SDK is available as the Maven artifact com.garmin:fit, which makes it straightforward to include as a dependency in Java applications.

Suppose a commercial Java application uses the FIT Java SDK to read and write FIT files and distributes the corresponding fit.jar together with the application installation package. The JAR would only be used internally by the application to provide FIT file interoperability and would not be exposed as a separate product, SDK, or development tool.

Could you please clarify whether this use case is permitted under the FIT SDK license?

More specifically:
- Is it permitted to redistribute the official com.garmin:fit JAR file as part of a commercial software product?
- Does the license restriction on distributing the FIT SDK apply only to the SDK itself as a developer package, or does it also apply to the runtime JAR when bundled with an end-user application?
- If redistribution of the JAR is not permitted, what is the recommended way to provide FIT file support in a commercial Java application?

Thank you for your clarification.

RE: Redistribution of the Garmin FIT Java Library

Ben FIT — Tue, 14 Jul 2026 19:38:34 GMT

The license agreement allows for the use of the SDK in commercial software. The license agreement applies to the source code and to the binaries, or source code, distributed through package managers such as Maven.

RE: Transfer data to Strava

7838061 — Mon, 13 Jul 2026 12:57:34 GMT

I ran into the same issue a while back. As far as I know, once the activity has already synced to Strava, edits made later in Garmin Connect usually don't sync over. Hopefully someone has found a workaround.

Transfer data to Strava

Gazz — Tue, 20 Feb 2024 04:40:09 GMT

Hi, My daily exercise routine is automatically transferred to Strava but this takes place before I have done my editing for specific sports etc. the result being that I have to then do the same edit in my Strava App. Is there any way of delaying the transfer until all editing has been completed on the Garmin App once the transfer takes place from my Garmin watch to the App. Cheers, Garry Smith

RE: Recommended integration architecture for a web-based cycling coaching platform

3034922 — Mon, 13 Jul 2026 06:38:04 GMT

Hello, UniPass login

For your use case, Garmin’s recommended path is to integrate through the Garmin Connect API (specifically the Activity API), which is designed for partner platforms to receive completed activity data—including FIT files—once users authorize access. This is the supported approach for post‑ride analytics and coaching platforms, as it ensures secure, automatic delivery of the original activity files rather than relying on summaries. If you’re planning a pilot with a small cycling community, you’ll need to apply for Garmin’s developer program and request access to the Connect API, since direct FIT file delivery is only available through that channel.

Recommended integration architecture for a web-based cycling coaching platform

7349784 — Fri, 10 Jul 2026 13:45:41 GMT

Hello Garmin Developers,

I am developing a web-based cycling coaching platform that analyzes completed cycling activities to generate personalized ride recommendations.

Unlike applications that only use activity summaries, our recommendation engine depends on the original FIT activity files because we derive additional physiological and performance metrics from second-by-second telemetry such as power, cadence, heart rate, GPS, elevation and speed.

Before implementing the platform, I would like to understand Garmin's recommended integration architecture.

For a web-based coaching platform where users authorize access to their Garmin Connect accounts, is the Garmin Connect Activity API the recommended approach for automatically receiving completed FIT activity files?

Or is there another supported integration that Garmin recommends for platforms performing post-ride analytics and coaching?

The platform is currently under development and will initially be evaluated with a small community of cyclists before a broader public release.

Any guidance would be greatly appreciated.

Thank you.

RE: Developer onboarding blocked

7349784 — Fri, 10 Jul 2026 13:41:31 GMT

Hi,

I'm experiencing something similar. I submitted an inquiry regarding the Garmin Connect Developer Program for a web-based cycling coaching platform and haven't received a response yet.

Has anyone recently been approved for the Activity API, or is onboarding currently delayed?

RE: Swim Interval Summary screen during programmed workouts.

6146796 — Tue, 07 Jul 2026 09:52:07 GMT

From what’s been shared by Garmin developers, the SDK doesn’t currently provide a way to trigger the same interval summary screen during rest periods that appears in free swim mode. The summary view with countdown is built into Garmin’s native workout logic, but isn’t exposed through custom SDK programming—so while you can design custom swim workouts, replicating that exact screen isn’t supported at this time.

www rootinsurance com

Swim Interval Summary screen during programmed workouts.

edwardsms — Fri, 03 Jul 2026 22:03:38 GMT

When programming a Swim workout via the SDK is there any way to get a Garmin Forerunner 970 to show the interval summary screen during the rest periods. The screen I want is the same screen the watch shows when doing a free workout. I swim some laps, press the lap button and a screen with a summary of the last set appears with a countdown timer for the rest period.

Requesting Manufacturer ID

4380222 — Fri, 03 Jul 2026 23:24:16 GMT

Hi, I work for a company that manufactures a device that produces FIT files. I'd like to request a Manufacturer ID to use instead of the developer value 255.

I gather this used to be done via thisisant.com. There is a form linked from https://www.thisisant.com/developer/resources/tech-support/ but I can't access that even when logged in as the highest level of membership currently available (ANT+ Adopter).

What is the process now that ANT+ Membership has closed?

RE: Requesting Manufacturer ID

Ben FIT — Mon, 06 Jul 2026 17:43:04 GMT

Send an email to eng.busdev at garmin.com with your request, and give them a few days to reply.

RE: python SDK weight_scale, weight - potential bug

8294519 — Wed, 24 Jun 2026 15:18:54 GMT

Thanks for the explanation and the fix! I uploaded some new data and it indeed has been corrected.

python SDK weight_scale, weight - potential bug

8294519 — Mon, 01 Jun 2026 17:58:28 GMT

I wrote an encoder based on the pythonSDK test_encode_activity_recipe.py. It seemed to work well except for the weight key like below:

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:5cc318b1-5781-4013-8ac1-7bb39107ff75:type=python&text=mesgs.append%28%7B%0A%20%20%20%20%27mesg_num%27%3A%20Profile%5B%27mesg_num%27%5D%5B%27WEIGHT_SCALE%27%5D%2C%0A%20%20%20%20%27timestamp%27%3A%20scale_date%2C%0A%20%20%20%20%27weight%27%3A%208400%2C%20%23decoding%20issue%3F%0A%20%20%20%20%27muscle_mass%27%3A%2066.0%2C%0A%20%20%20%20%7D%29Code]

The 'weight' is a weight type and supposed to be in kilograms; however, it seems to scale incorrectly (8400 instead of 84.0kg). The other keys that use mass (eg/ muscle_mass) all convert from to kilograms okay when uploading the FIT file to Connect. Perhaps it's a type weight vs type unit16 issue? Thoughts?

Thanks!

PS Hopefully I'm writing this in the correct place, apologies if not.

RE: attrezzatura

Ben FIT — Tue, 23 Jun 2026 19:43:12 GMT

There is a similar question in the Connect Web App forum. I suggest posting your question there to show your support for this feature request.
RE: Gear Tracking

attrezzatura

2025128 — Thu, 18 Jun 2026 09:53:39 GMT

come faccio ad azzerrare i km dell'attrezzatura? Ho appena impostato catena e copertoni, ma uun copertone ha 2.000 km come faccio a cambiare i km e non farlo partire da 0? grazie

RE: python SDK weight_scale, weight - potential bug

Eli FIT — Wed, 17 Jun 2026 14:00:51 GMT

With the release of the 21.208 SDK, this behavior is now fixed. Weight in the weight_scale mesg is now properly a uint16 and will apply scale as expected when either encoding or decoding data.

The new version was published to PyPi available here: https://pypi.org/project/garmin-fit-sdk/

Create workout with steps using the SDK

RePeter — Wed, 10 Jun 2026 17:04:19 GMT

Hi,

I am currently developing a strength training application for my Garmin watch. The application is able to record an activity using the Toybox.ActivityRecording.Session.

After running the workout with session.start(), session.stop() and session.save(), the activity is stored on my device and is uploaded to Garmin Connect.

If I create a strength training with my watch using the standard strength training app, I have a number of sets including reps, the time of the set and the time of the pause. It looks like this in Garmin Connect:

When I create an activity with my self made application, I cannot add any sets to the strength training. The method 'createFIeld(...) is not creating the correct data field in the FIT file.

By decoding the FIT file from my watch, I found the required data that is used to create the sets inside the Garmin Connect app:

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:66143fb5-27f4-4464-9b95-f692981de9d2:type=text&text=%5B%0A%09%7B...%7D%2C%0A%09%7B%0A%09%09%22frame_type%22%3A%20%22definition_message%22%2C%0A%09%09%22name%22%3A%20%22set%22%2C%0A%09%09%22header%22%3A%20%7B%0A%09%09%09%22local_mesg_num%22%3A%202%2C%0A%09%09%09%22time_offset%22%3A%20null%2C%0A%09%09%09%22is_developer_data%22%3A%20false%0A%09%09%7D%2C%0A%09%09%22global_mesg_num%22%3A%20225%2C%0A%09%09%22endian%22%3A%20%22%3C%22%2C%0A%09%09%22field_defs%22%3A%20%5B%0A%09%09%09...%0A%09%09%5D%2C%0A%09%09%22dev_field_defs%22%3A%20%5B%5D%2C%0A%09%09%22chunk%22%3A%20%7B%0A%09%09%09%22index%22%3A%2013%2C%0A%09%09%09%22offset%22%3A%201546%2C%0A%09%09%09%22size%22%3A%2051%0A%09%09%7D%0A%09%7D%2C%0A%09%7B...%7D%0A%5D]

Therefore, I tried to create the data inside my application, but haven't found any way to create the data field for sets.

Does anybody know, how to add the sets to my application, so I can view the sets inside the Garmin Connect app?

Discussion - Recent Threads

How to get RR intervals from FIT hr messages (Fit file message 132)?

Type‑12 Anchor Processing

Type‑11 Message Processing (The Core RR Extraction)

1. Scalar event_timestamp

2. Packed event_timestamp_12 (field 10)

Result per Type‑11 Message

Fenix 6 product names in fit sdks seem to be wrong?

Accidental duplicate post. Please delete this Discussion copy and retain the Question version.

How should more than five RR intervals from one BLE notification be serialized into FIT hrv messages?

Developer onboarding blocked

RE: Developer onboarding blocked

Sending HR Data from Samsung GW5 to Edge 530

RE: Redistribution of the Garmin FIT Java Library

Redistribution of the Garmin FIT Java Library

RE: Redistribution of the Garmin FIT Java Library

RE: Transfer data to Strava

Transfer data to Strava

RE: Recommended integration architecture for a web-based cycling coaching platform

Recommended integration architecture for a web-based cycling coaching platform

RE: Developer onboarding blocked

RE: Swim Interval Summary screen during programmed workouts.

Swim Interval Summary screen during programmed workouts.

Requesting Manufacturer ID

RE: Requesting Manufacturer ID

RE: python SDK weight_scale, weight - potential bug

python SDK weight_scale, weight - potential bug

RE: attrezzatura

attrezzatura

RE: python SDK weight_scale, weight - potential bug

Create workout with steps using the SDK

1. Scalar `event_timestamp`

2. Packed `event_timestamp_12` (field 10)