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Ask HN: Is there a fitness wristband that is hackable?

197 points by kuon ↗ HN
I'm looking for a wristband/watch/"thing on the arm" with GPS, heart monitor and pedometer(accel+gyro).

I looked at what is on the market, but sending my bio metrics to fitbit or garmin servers is not something I want to do.

Is there a fitness tracker band that is hackable in a sense that I can get the data out of it without proprietary software? I don't mind the firmware being closed source, as long as there is no LTE. I just want to sync and manage my data myself.

121 comments

[ 5.0 ms ] story [ 193 ms ] thread
nl
Don't the Garmin watches still have USB access to the file system?

The old ones did, and even the newest Garmin Edge series cycling computers let you do this. They run (mostly) the same firmware as the (high-end) watches, so I'd be surprised if they don't.

kuon
That would be interesting to know. As long as the files are not obfuscated too much that could be a solution (I'd like to avoid having to reverse engineer a binary format).
asandweech
Activities are stored in the FIT format, which is publicly documented and they have a rather easy to use sdk available for it as well[0]. Its fairly trivial to get other daily metrics out of the watch as well using Connect IQ, you can even write out to a plain text log file if you want.

[0]: https://www.thisisant.com/resources/fit/

kuon
That's great. Filesystem access and open format.
bitexploder
Yes. At least my Fenix 3 and Fenix 5X do. You can write apps for it. So it is hackable in that sense.
amjaeger
These guys started from a kickstarter 3 or 4 years ago, and are still in business. I bought one but never had time to use it. https://mbientlab.com/
LordAragorn
A few years back, I played around with TI's EZ430-Chronos: http://processors.wiki.ti.com/index.php/EZ430-Chronos?DCMP=C... It's not sleek like modern fitness bands/watches but is hackable.

TI has more Smart Watch components and reference designs here: http://www.ti.com/solution/smart-watch

zokier
Chronos is neat, but it isn't really fitness oriented and notably it doesn't have any of the sensors OP wanted (GPS, heart rate, gyro)
kuon
The Chronos looks like a sci-fi watch. I like it, but it lacks what I want for fitness.
TeMPOraL
Chronos is cool, and definitely hacker-friendly, but it's not a proper fitness watch per se - it's just a demonstration TI made for their CC430 chips. Doesn't have much computational power or sensors onboard, but it features an 433/868/915 MHz radio (frequency depends on the model you pick) - and I mean actual, hackable radio - and it lasts forever on a coin cell.

I had lots of fun tinkering with it, but it's not really what the OP is looking for.

piqufoh
The was the "angel" on indiegogo - but they tanked before delivering any of the "perks" (product). I lost $249 there - still a bit sore!
smartt
FWIW, I switched my order to the stripped-down "angel" and did eventually receive it but it was non-working junk. Some sensors didn't work; others produced garbage for data. So disappointing.
qrbLPHiKpiux
Anything is hackable.
neilsimp1
True, I guess, but with how much effort? I think OP wants something he can jump into, not something he has to basically re-engineer. That said, "Anything is hackable" is a good spirit to have.
kuon
That's true, I hacked the rear view camera of my car to draw guide lines connected to the wheel position using a pi[1], but it took me tons of effort to reverse engineer the wiring system and CANBUS of my car, I learned a lot (CANBUS is a lot of fun:P), but I don't want that level of involvement here.

But I'd like something easier to work with, the "data accessible on the filesystem" of the Garmin seems to be the perfect balance between effort and "hackability".

[1]: https://github.com/kuon/backup-camera

jat850
Having worked extensively with CANBUS and other vehicle interfaces, I cannot remember ever using the word "fun" to describe that line of hacking... :)
chtpt
Was just about to post a very similar comment. If I was OP I'd buy something cheap (so it doesn't matter if I break it while hacking) and pick it apart until I could get the data.

I'm surprised that you're getting downvoted for this sentiment on a forum that is supposedly "Hacker News". Come on people, where's your hacker spirit?

oafx
If you can go without GPS maybe have a look at the MI Band 2.. afaik there is sone kind of third party app android that allows you to sync and export the data without the mi software..
kuon
GPS is really nice for running, I thought about making drawings with my running trails. I need motivation:P
barryridge
I'm not sure if this really fulfills your "without proprietary software" criteria, but Polar recently announced that they've opened up their API for developers. I believe you do need to have a Polar Flow account though, so the API access works along the same lines as the Google API, i.e. using OAuth 2.0 authentication that connects to your Polar Flow account, which the watch syncs to via phone/wifi. So there's no LTE, but the watch does sync to the Polar Flow account in the cloud via phone/wifi. Their M600 watch is an Android Wear device though, so it might be possible to write an app for that to access the data directly, but I'm really not sure about that part.

https://www.polar.com/en/developers

dirtbox
Pebble. Someone installed linux on one and they're extraordinarily cheap to pick up now.
kuon
I looked at Pebble and I was surprised to see they were out of business.
dirtbox
Which, from your point of view, isn't a bad thing. It's no longer dependant on external servers, yet still enjoys a lot of support, is easy to code for, plus it's superb as smart watches go. Charging 3 times a month rather than every night means you can track your sleep with it effectively as well.
johnchristopher
The alta HR I bought this year and use for sleep tracking has 5 days of battery.
zodPod
What is the battery life difference you mention? The lack of external servers or do you mean because it'll have linux on it now?
dirtbox
It lasts up to 10 days on one charge and the app has been decentralised, meaning it's not reliant on external servers.
zodPod
Aah ok you meant the pebble in general. I agree I loved how long the pebble lasted! I was hoping there was some upgrade that made it last even longer haha. I might have to do this though, attempt to install linux on it!
Crespyl
I understood the comment to be referring to other fancier smartwatches that are designed around ~daily charging.
zodPod
Aaah, makes a lot of sense! Thank you for the clarification!
TeMPOraL
It is a bad thing, because electronics get old and eventually die. There isn't really any other company like Pebble on the market (Garmin is probably the only contender here), featuring quality hardware, e-Paper screens and a hacker-friendly ecosystem. So when your watch dies, you'll be forced to downgrade.

(I'm a happy owner of Pebble Time, and I dread the day it lets out the magic smoke.)

dirtbox
Hah. You're not wrong about calling it a downgrade. Absolutely everything I've tried has been a downgrade from pebble. It's as if everyone is deliberately avoiding what was, for me at least, perfection.
24gttghh
Source? Are you referring to Rebble.io?
dirtbox
Someone posted a proof of concept a year or two ago on reddit.com/r/pebble Beyond that I don't know any specifics.
blackfawn
If you are hardware inclined and can use something else for GPS, some of the inexpensive fitness bands from Asia contain Nordic nRF51 / nRF52 microcontrollers and are completely reprogrammable. Roger Clark's site has some good info including http://www.rogerclark.net/arduino-on-the-id100hr-fitness-tra... (I believe the watch pictured is actually an ID107HR, not an ID100HR) The ID107HR is nice because it opens with a few screws rather than cracking glue apart and it also exposes the programming pads. You can write Arduino code and interface with the heart rate sensor, accelerometer, OLED screen, etc.
kuon
Even if I'm more inclined towards an easier solution like the Garmin for fitness tracking, this looks interesting for pure tinkering.
j45
From a fitness & android perspective - android wear has very few devices with many of the useful sensors in one watch.

I have recently ordered a TIQwatch from the most recent kickstarter and hope between it, TaskerWear, etc, that it might be the first androidwear device that values both sensors and optimizing battery life. I know I should be able to get at the data in it how I want. Companies like Samsung have left AndroidWear.

The watch is reasonably priced compared to alternatives, and I hope may be the first smartwatch I end up keeping.

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guptaneil
If you have an iPhone, an Apple Watch meets your description perfectly. It has GPS, heart monitor, and pedometer data, and stores it in your local HealthKit database, which you can easily read and write with your own Swift code running on an iPhone. You can also write apps for the watch directly, and there is a non-LTE model.
toyg
> you can easily read and write with your own Swift code running on an iPhone

... after easily paying your Apple Developer Subscription, that is.

knolan
No, there is no charge unless you start to put apps on the App Store.

https://www.pcworld.com/article/2933052/apple-frees-casual-i...

lern_too_spel
The app will only run on your phone for 7 days[1] unless you pay Apple an annual fee, which is a non-starter if you want to write an app that you will actually use instead of merely test.

No such restrictions on Android, Windows, or other platforms. Moto Sport 360[2] looks like it will fit OP's requirements.

[1] http://mybyways.com/blog/new-limitations-imposed-on-free-app...

[2] https://www.motorola.ca/products/moto-360-sport#Specificatio...

PierceJoy
> which is a non-starter if you want to write an app that you will actually use instead of merely test.

You're assuming OP doesn't want to pay for a developer account. They didn't say that.

Also, OP said they wanted to get data out of the device. The Health app has an export function. So no, you don't need to pay to do what OP wants.

I would take an Apple Watch + paid developer account any day of the week over Android Wear.

lern_too_spel
> I would take an Apple Watch + paid developer account any day of the week over Android Wear.

You've given no reason why. You're assuming OP is a mindless fanboy who will pay for something that has a free and more hackable alternative.

PierceJoy
> You've given no reason why.

I don't have to. It's my opinion.

> You're assuming OP is a mindless fanboy who will pay for something that has a free and more hackable alternative.

I'm sure that's your neckbeard interpretation. There's a reason the Apple Watch is the most popular smart watch by far. You probably think it's solely due to marketing. You would be wrong.

aembleton
Amazfit Pace [1]

I just bought one for ~£80 from Gearbest and you can pull the GPX routes from it, and also add routes. You can access all of the files, by plugging a USB lead into the charging dock. It then appears as a USB drive that you can copy files to and from. I've designed my own watch face, as it's just XML and image files and taken GPX data. I'm not sure how or if you can get the heartrate or pedometer data but there is a community on XDA [2] around it so they might be able to help.

The thing that I'm most impressed by is the screen. It is a transreflective display which means that it is always on and just uses the latent light for you to be able to see it, much like a black and white LCD. It does have a backlight, but you only need to put this on when it is dark and you actually need to see the display - much like watches used to be.

1. https://us.amazfit.com/shop/pace?variant=25112

2. https://forum.xda-developers.com/smartwatch/amazfit

dspillett
What sort of in-use battery life do you get on that? If I were to use it for an ultra run next year, would it be able to last 12 to 18 hours with GPS tracking on for most of that time?

I see the "5 day" claim on the site but these tend to be vastly exaggerated (based on absolutely perfect conditions with everything other than just the watch and maybe step counter functions turned off) in my experience.

aembleton
I've only had it for a week, but I managed to run the GPS for 12 hours and the battery was at 65% afterwards.

From that, I would say >30 hours is do-able.

I last charged mine 3 days, 16 hours ago (the phone app tells me). It is currently at 36% charge. That is with sleep tracking and constant heart rate monitoring as well as getting all of my notifications from my phone. 5 days is legit.

craftyguy
OP said:

> but sending my bio metrics to fitbit or garmin servers is not something I want to do.

The device you linked to sends all information to Strava, which isn't really any better than what OP DIDN'T want to do...

aembleton
It only sends it to Strava if you want it to. I haven't connected it to Strava yet, although I probably will eventually.
jrowley
Wow this is a really interesting/nice looking product at an impressive price point. I wonder how well the GPS works. It has GLONASS so I am impressed. Almost makes me regret shelling out for a garmin 735...
darklajid
No.

I bought it when Pebble went down. That thing was buggy forever after, half Chinese most of the time, only allowed sync to a random online service (strava?) and was just.. broken. The worst purchase ever.

The display sucks outside. The software is weird (swipe in random directions to find what you want), the companion app miserable.

Whatever you buy, this shouldn't be it.

A better Pebble would be appreciated ofc..

toyg
Strava is hardly "random", it's very popular in UK with cyclists and runners.
ksenzee
It's popular with cyclists in the US also. My colleagues who bike to work all use it.
darklajid
Random in so far as that I don't use it, don't want to sign up for it. A random cloud service and just ONE random cloud service.

When I got it, you couldn't even see your own data on your phone. HR? Steps? GPS? Stava or gone, poof.

aembleton
If you've still got it, see if you can get an Enlgish ROM. Sounds like you might have been running the Chinese version.

What do you mean by the display sucks outside? Couldn't you see it? Was it night time?

darklajid
It has a weird "reflctive" display which is supposed to make it readable in bright daylight. It doesn't, in my experience (couldn't read it quite often, a Pebble works perfect though)
aembleton
I haven't really had any bright light recently and probably won't until the summer. I guess, then it might be a problem for me.
giancarlostoro
Some people have hacked the fitbit's synching to save to your personal computer instead of to their servers. I haven't done it since I went with the FitBit Ionic, and it auto syncs. I do like how easy it is to make apps for it though.

Edit: Check out Shimmer:

http://www.getshimmer.co/

Apparently syncs with different devices.

MrQuincle
Are you sure? It looks like it does requests to the Fitbit servers.

I've done some reverse engineering myself at https://github.com/mrquincle/fitbit-fatbat, which gets part of the data from the early devices. However, I'm not aware of anyone cracking the encryption and obtaining the rest of the data.

LeifCarrotson
I have a Garmin Forerunner FR220. When plugged into a Windows 7 computer by the USB device, it shows up as a USB Mass Storage Device, initializing a "Garmin FR620 Flash USB Device", and connects as FAT formatted Flash storage.

Seeing 620 does cause me a bit of annoyance, as I know that my 220, which lacks a number of features of the 620, watch is physically identical just with the speed inhibitor turned off [1]. Makes me miss my TI 430 Chronos, but that didn't have GPS. The FR225 is the first version with the optical heart rate monitor, but I believe it and the current FR235 will behave similarly.

All the activity data is stored on the mass storage device in .FIT files. Here's an example file [2] which you can compare to my Strava upload at [3]. Use the tools at [4] to convert and edit it into GPX format, and the schema at [5] to tease out pedometer/heart rate data from this XML text. You'll probably end up using GPSBabel [6] to analyze it.

Garmin is probably the most common activity tracker for actually running, biking and so on. For just sleep tracking and resting heart rate tracking, or daily step counters, Fitbits that lack GPS are much more popular. But they don't allow manual export of data [7]:

> Welcome to the Fitbit Family @JohnDiver! The stored data on your Fitbit Flex can be taken out only via Bluetooth with an internet connection. It can be synchronized with a computer or with a supported mobile device. Your tracker stores at least 7 days of detailed minute-by-minute data. Summary data (calories, distance, and steps) will be stored for 30 days. If you are experiencing syncing issues, please take a look at the basic troubleshooting steps.

> If the above doesn't help you please let us know what type of difficulties are you having to transfer your data to your Dashboard? Looking forward to your new comments!

The new Garmins do have activity tracking features; I'd be interested to see if their data can be accessed as easily as the .FIT activity files.

[1]: https://www.joelonsoftware.com/2004/12/15/camels-and-rubber-...

[2]: https://drive.google.com/file/d/1H6sBu3XaQgUyTyAhO1Oz7jKL0hx...

[3]: https://www.strava.com/activities/1287343609

[4]: https://www.dcrainmaker.com/tools

[5]: https://www8.garmin.com/xmlschemas/TrackPointExtensionv2.xsd

[6]: https://www.gpsbabel.org/

[7]: https://community.fitbit.com/t5/Flex/Retrieve-raw-data-from-...

GrinningFool
I wonder how practical it is to create "thing" with no exposed face, no wireless, no connectivity. It'd provide continual heart rate and respiration monitoring. A few dedicated buttons that just log when they're pressed - when parsing the data you can map that to whatever meaning you want. Offload csv files via USB, and do with it what you wish.

perhaps bluetooth so the would-be hacker could write a phone app to present data

Xeoncross
I would by "thing" with nothing more than:

> A few dedicated buttons that just log when they're pressed - when parsing the data you can map that to whatever meaning you want.

robryk
Would you mind sharing what would you use such a thing for? Counting events or timestamping them?
curtpw
There are a number of Chinese generic activity trackers containing the Nordic nrf52832 MCU and a GPS module which are easily hacked and would meet all your needs. Search for "nrf52832 gps bracelet" or "nordic gps bracelet" on Aliexpress, Banggood, ebay etc. For example: https://www.aliexpress.com/item/KINCO-OLED-GPS-Activity-Trac... Components: Nordic nrf52832/ARM Cortex M4 MCU, Kionix KX023 accelerometer, Ublox GPS module, 200mAh battery, 0.96" OLED screen. This can be programmed using the Nordic SDK with Keil, ARM mbed, Sandeep's Arduino Core for nrf5X etc.
queeerkopf
Do you know any blog posts or similiar where this is described in more detail?
VectorLock
Might be easily hacked, but has anybody hacked them?

I contacted a few sellers on Aliexpress because I wanted to see how many I had to order to get them to give me the source code so I could make a value-added product from them but it was beyond what I was willing to invest.

curtpw
I have hacked the MCU and accelerorometer. Haven't gotten around to the GPS yet, lots of projects and this isn't at the top of the list. Its just hardware, all the components are well known, you can just lookup datasheets and go from there. I can post microscope pics of the PCB if you like. What is the best way to post/link pics on HN?
retSava
just out of curiosity, since I was surprised to hear they even had that option, how many did you need to order for that?
kybernetikos
I'm currently using a logitech keyboard and mouse that support their new feature 'flow' that allows your keyboard and mouse to switch which computer they are paired with when the mouse goes to the edge of the screen. Now it seems that to support this feature, they must have the ability for the computer to instruct the keyboard and mouse to switch to one of the other paired computers. I would very much like to have the capability of doing that in my own code, but it seems to only be available through the official logitech app (that rarely works for my setup).

I've got an ereader that requires me to plug in to transfer epubs that I've downloaded onto it. If it were hackable, I'd be able to run a wifi sync program on it and my experience would be much better. It integrates with pocket, but I use pinboard.in and would like it to integrate with that instead. The default software doesn't give me a choice.

I've often wanted to purchase things based on their hackability - wifi routers, keyboard, mouse, sd cards, voip adapters, game controllers, cameras, e-readers, mobile phones, webcams....

But I often find it very difficult to find up to date information about what is user-hackable and what isn't. If this information were easier to find, it would affect my buying decisions more and would create more incentive for manufacturers to consider making their devices hackable.

JustSomeNobody
Logitech flow looks interesting. From the 30 seconds I scanned the page about it, it seems the computers need to be on the same network. So this could be as "simple" as running tcp client on each machine. When the current active machine notices that the mouse left the edge of the current screen it disables the keyboard and mouse on current machine, sends a notification to the other computer and enables keyboard and mouse there. Custom USB drivers could likely handle disabling and enabling the keyboard and mouse just fine, but I've never written one, so maybe I'm wrong.

Edit: I was speaking more generically here. I doubt one could get the actual Logitech mouse and keyboard protocol and so couldn't implement an open source flow clone.

robbles
Synergy (https://symless.com/synergy) does exactly this, cross platform, and really effectively.

You don't need to write your own using a Logitech driver - it works with any standard keyboard / mouse.

netsharc
Synergy stopped working for me one day, and it seems all machines have to use the same version. And they pivoted from free to charging for money.

I guess Logitech is doing the same thing, but if they actually implemented it by unpairing the input devices from one receiver and pairing it to the other, that would be cool, it means I can turn off the unpaired computer, and input still works on the paired machine.

Rondom
It's still open source. So you can compile it yourself, if you want.
kybernetikos
If you turn off the master computer or it crashes when the keyboard and mouse are controlling the other one, you're stuck. I would assume that this is not the case with Logitech Flow, since the keyboard and mouse genuinely do connect to both.

Incidentally, 13 years ago, I used to use something very like what you're describing, back then it was called Win2VNC and X2VNC

But the point I'm making is nothing to do with the seamless desktop thing, it's that the ability to switch input between different devices is something I'd like to be able to write code to control in all kinds of situations (time based, in response to events, etc), not just when the official software thinks I should or when I press the physical buttons on the device.

theli0nheart
Pretty much any Garmin device does exactly what you're looking for. All of the activity data on my fēnix 5 / VA HR is visible when I plug in via USB. The data is encoded in the FIT file format, which has a public SDK [1] (you do need to accept a license agreement to view it, though, if that matters). There are wrappers for most languages and if you want to just translate the data to CSV, there are pre-made tools to do that too.

I don't think you need to enable sync, so keeping the data local wouldn't be an issue. AFAIK, you should just be able to use the Garmin Connect software once to set up the watch, and that's it.

The great thing about the Garmin watches is that pretty much any fitness hardware that uses ANT+ will work with them. ANT+ is also an open protocol so you're not locked in with a specific manufacturer.

[1]: https://www.thisisant.com/resources/fit

ISL
I am unwilling to accept an SDK's license in order to view my own data produced by my own hardware.

So, a couple years ago, I wrote a bash-wrapper [1] to Suto's perl FIT-parsing library [2]. With a quick search, I see that others may have extended Suto's work [3].

I'm pro-Garmin but can't understand hiding a measurement instrument's output format behind a closed-door license.

[1] https://github.com/4kbt/ParseVivosmartHR

[2] http://pub.ks-and-ks.ne.jp/cycling/GarminFIT.shtml

[3] https://github.com/mrihtar/Garmin-FIT

sliverstorm
Isn't SDK licensing pretty normal, outside of open source?
yjftsjthsd-h
> outside of open source

Yes? By definition, if it's not open source, then you're looking at a proprietary license of some sort.

sliverstorm
What I meant is the outside-of-companies open source community.

It's not weird for a company to license their SDK, no matter what it's for. Par for the course rather.

mhluongo
That's not by definition at all- a work can be open source with a "proprietary license of some sort", or closed source, with source that's liberally licensed- but never published.
ISL
The trouble is that the FIT file specification, in addition to the parsing libraries, is behind the license.

It is possible to state the definition of a file format without opening any proprietary code.

mikestew
I'll confirm the Garmin route as the way to go if you don't want to make a career out of getting the data off whatever Chinese bobble you found on AliExpress. You can get as fancy, or not, as you want. Plug into USB, drag-and-drop files somewhere and hackity hack. Or get all fancy and write wrapper code to prettify the data.

I don't think the watch ever needs to connect to anything in order to set it up, it can all be done on the watch (though Garmin Connect will make it easier). I do know that once it's set up, you can just turn the radio transmitters off and work through USB.

i_am_nomad
Seconded on Garmin, Tactix Bravo owner here. They’ve made a serious effort to support their developer community, and as such I’ve written a few apps and watchfaces for it. And as you say, there are many options for viewing and manipulating the data - IIRC, you can even download it from their servers after you’ve synced it, if you prefer.
Psilidae
I'm not sure if this is a question about Garmin or ANT+, but assuming a device is Bluetooth enabled, is there documentation for the Bluetooth API? I really want to find a nice smart fitness thing, but no one makes apps for my phone, so I figure I'd need to make one myself.
pavlov
Samsung's latest generations of fitness wearables (e.g. Gear Fit 2) run the Tizen OS, which is a complete Linux stack. You can actually SSH into the wearable over wi-fi.

The development stack is kind of a mess, but if you know Linux, I would look at those.

scaphandre
Interesting. I had assumed Tizen was a greatly reduced Linux-inspired OS. Do you have a source for the ability to SSH?

Might it not be easier to have an Android app that grabs data from the watch using their API?

https://stackoverflow.com/questions/40233692/how-to-integrat...

pavlov
Do you have a source for the ability to SSH?

I've used it myself on several models: Gear S2, Gear S3, Gear Fit 2.

Tizen is a full Linux. If I remember correctly, it even runs X for the GUI (although I think it's been replaced with Wayland in Tizen 3).

scaphandre
Ok cool.

But how is it that you are managing to connect via SSH? When connected over wifi, it seems that only port 53 is open on the Gear S3, and it doesn't accept SSH. And I don't know the user name nor password. And I don't see a way to open a terminal on the watch.

Googling doesn't seem to help.

jmiller099
motoactv fits the bill also.

I even hacked it's golf database to update for the Torrey Pines North redesign which occurred last year.

For the other data pulls, the xda folks did that.

Garmin may also work, depending your use case. I couldn't get golf working without their service, so I leave it unused. used some java library found online to parse their .fit files within an android app, so can get data on my phone without going through their servers.

echelon
Is there a way to extract real time information from a Fitbit or similar fitness wristband? I'd love to push running data to a display I can see as I jog by.
brlewis
Only Ionic. For other Fitbits you have to get data from the api later.
robterrell
If you want to do a lot of hacking, I was just looking at the Hexiwear: http://www.hexiwear.com

It's an ARM dev board with screen in a watch-like form factor. It has all the hardware you're looking for except GPS, but they sell a lot of add-on modules.

I say "a lot of hacking" because I imagine you'd have to write all the fitness tracking software yourself, unless you find something similar on https://www.hackster.io/contests/Hexiwear