
Hacking a cheap fitness tracker bracelet - miqkt
https://rbaron.net/blog/2018/05/27/Hacking-a-cheap-fitness-tracker-bracelet.html
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jmptable
If someone were able to find a reliable source for the same band this work
could turn into the nucleus of many wearable projects. It's hard for beginners
to build electronics that are 1. small 2. comfortable 3. power efficient.
These bands already take care of all of that.

There are many applications for this sort of platform. One could easily build
a discreet pen testing tool which records information it sees about Bluetooth
devices nearby. Or create an embedded engineering Swiss Army knife which
exposes IO on your wrist to an app on your phone so you can jack into gadgets
you find and poke around on the spot. Fun social applications to try too, like
buying one of these for every attendee at your conference and building peer-
to-peer applications on top.

Mapping out the programming interface is essential to enabling all that fun,
but so is finding a reliable source for these devices.

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netsharc
One simple hack I can imagine is a text-to-morse transmitter. He's figured out
how to vibrate the motor, if one can have an app that reads the phone's
notification and talks over Bluetooth, one could convert it to morse so the
user can receive his messages through vibrations in his wrist.

Although I suppose it would remain as a hack, if my I programmed this and
bracelet starts vibrating the first thing I would do is pick up my phone to
use my eyes instead of the morse code...

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roel_v
If anyone is looking for a business idea, if you could hack these things to be
a remote control so that dance teachers can use it to pause/play and skip-to-
next on the cheap and without having to run to their phone, that would sell
like hotcakes. Typical scenario now is: teacher plugs phone into amp, then
needs to run up and down to phone every 5 minutes. Having a bluetooth
connection so that the bracelet can work as a play/skip remote for the phone
would be enough. Range might be an issue, needs to be 30 meters (reliably) or
so.

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jdiez17
Can't most (or at least, many) of these BLE fitness bands act as music
controls for smartphones already? I know that every smartwatch under the sun
does this, and since it's just a software feature, I feel it's such low-
hanging fruit that every off-brand manufacturer must have implemented it a
long time ago. But maybe I'm wrong?

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roel_v
From what I could tell, they all act as music players, not as remotes. But
yes, I too thought this would be something obvious.

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eli
I bet all the hybrid smart watches work as remotes. I had a Skagen that did.

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diehunde
I'm curious about the level of expertise you need in order to do this. I also
have a cheap bracelet and I wanted to do the same thing, but reading this
article seems like you need to be an expert in
electronics/lowlevelprogramming.

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r4pha
Hi, author here. I can honestly say that I’m definitely not an expert. I tried
to systematically write down questions on a text file and solve them one after
the other. Solving one usually added a few other ones. “What chip is this?”,
“how to program this chip?”, “do I need a development board?”, “what’s SWD?”,
“how to pull an output high?” Etc. Lots of these are specific to this chip,
too, so a lot of it is just reading the documentations and drilling down on
libraries.

It’s something I find refreshing to read and like to state when I can: none of
this was easy for me. But it was definitely fun. Having no deadlines helps.
Having no practical goal and just enjoying the process was also refreshingly
nice.

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introiboad
Hi author, nice hacking and writeup!. Nordic employee here. Note that if
instead of the SoftDevice and the SDK you would've used Zephyr then you'd be
able to do the same you did but with a fully open source software stack,
including all layers of the BLE protocol stack. More here
[https://github.com/zephyrproject-
rtos/zephyr](https://github.com/zephyrproject-rtos/zephyr)

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r4pha
First time hearing about this. Looks awesome. Thanks for the tip!

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JofArnold
Awesome work and inspiring write up. I’ve started doing similar things lately
and I can imagine exactly how much grinding was involved to get the end
result. You must have felt great when the display finally showed the image :)

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r4pha
Thank you. Getting the display to work was very motivating for next steps :)

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anonu
> I look very much forward to rellocate it all the way to the back of my
> drawer and leave it there for some time.

This is funny - I feel the same way about a lot of side projects I undertake.
Great writeup btw. I feel like this type of stuff gets harder and harder as
ICs fit into tighter packages. Glad someone is taking the time to explore.

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qwerty456127
As far as I can see it doesn't do the heart rate monitoring - the only thing
on the features list a smartphone can't do. What I really want (writing it
here just in hope somebody might know a suitable model) of a hackable fitness
device is to supply reasonably precise real-time heart rate data letting my
DIY Android app react on its change.

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ultrasounder
Very nice and extensive write-up.have always been curious about these Nordic
devices that seem to be so pervasive these days.

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canada_dry
Anyone know where to find this particular bracelet on ebay or alibaba?

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Markoff
search for ID115 on Aliexpress

