Hacking Wearables for Mental Health and More

Arduino compatible nRF52 ARM prototyping platform used by MATTER Lab. Tutorials & code for gesture recognition and machine learning.

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Full tutorial on hacking the X9 Pro activity tracker so you can use it as the foundation of your next project. MATTER Lab hacks generic activity trackers and uses them as a platform for prototyping and researching mental health wearables. We have built a gesture recognition and biofeedback device for compulsive mental health disorders - as well as a hand position tracking device independent from cameras or other external references. Although the activity trackers we hack are wrist-based, we've built all sorts of devices with them - even ones worn inside our mouths! We are open sourcing this platform and making it completely Arduino compatible for your convenience. Full smartwatch hacking documentation + tutorials and code for accelerometer gesture recognition, neural network training, and 3D model control using Bluetooth.

For the past two years I've been using hacked generic activity trackers as a rapid prototyping platform for wearable devices - primarily gesture recognition biofeedback and position tracking devices at the CMI MATTER Lab, a research institute focused on children's mental health.

My goal is to present generic nRF52832 and nRF51822 ARM Cortex activity trackers, in particular the X9 Pro, as a full fledged platform for prototyping low power devices accessible to anyone familiar with Arduino.

The $35 X9 Pro Activity Tracker is equivalent to ALL these Adafruit Products COMBINED:

TOTAL: $95.70   not including brushed steel enclosure, silicone strap and general miniaturization

Devices That Use This Platform (see Project Logs):

  • "Tingle", a gesture recognition and biofeedback device for compulsive mental health disorders like trichotillomania and excoration.
  • "Thermo", a hand position tracking device that does not require an independent camera or other external reference data (think mobile Oculus and HTC Vive controllers).
  • Intraoral Respiration Monitor for Overdose Detection - a computer (hacked smartwatch) worn entirely inside your mouth with air pressure, humidity and temperature sensors.

Tutorials and Example Code:

  • Blink, Button, OLED, Web Bluetooth (GATT Notifications) and Bluetooth Serial debugging Arduino example sketches that work with the X9 activity trackers (and most other activity trackers mentioned in this project with slight modification)
  • Use of neural networks (LSTM MLP by way of synaptic.js) for gesture recognition using accelerometer data from the X9 streamed into a web browser over Web Bluetooth
  • Accessing additional GPIO ("pins") so you can customize your device and add additional components

Neural Network Gesture Recognition with Web Bluetooth Tutorial

Stream sensor data from your hacked activity tracker into a web browser using the experimental HTML5 Web Bluetooth API. Sample data in different positions and train a neural network to distinguish position ie recognize gestures.

Got to the live site site HERE      GitHub Repository for live site HERE

This is a GitHub site so all you have to do is fork the GitHub repository and you can create your own version of this site in seconds. Customize and hack it! (info on Web Bluetooth)

X9 Pro Activity Tracker Components

  • nRF52832 ARM Cortex M4 SoC/MCU
  • vibration motor
  • 96x64 Color OLED display with SSD1331 controller IC
  • Kionic KX126 Accelerometer with interrupt...
Read more »


Example demonstrating text communication between the X9 activity tracker and an Android phone application including automated reply and text color changes

ino - 14.91 kB - 05/24/2018 at 15:11



Example for displaying text on the OLED display using a lightweight font

ino - 10.73 kB - 05/24/2018 at 15:09



This sketch makes the green heart rate sensor LED blink

- 1.21 kB - 04/18/2018 at 23:15



This sketch uses the touch sense button to control the heart rate sensor LED and the vibration motor.

ino - 1.88 kB - 04/18/2018 at 23:47



This sketch will show you how to display data on the color OLED. This example displays the Hackaday logo scrolling across the screen and randomly changing colors.

ino - 40.38 kB - 04/18/2018 at 23:24


View all 8 files

  • 1 × X9 Pro Activity Tracker Nordic nRF52832 ARM Cortex M4 based activity tracker with color OLED, KX126 accelerometer, 8MB SPI FLASH Memory, heart rate sensor and touch sensor
  • 1 × A SWD capable programmer: J-Link, Black Magic Probe etc.

  • Text Communication over Bluetooth Serial Example

    Curt White05/24/2018 at 07:52 0 comments

    I have created a simple font for the X9 OLED display and used it to demonstrate text communication over serial Bluetooth using my Android phone. The BLE_CHAT example will display input from the Nordic phone app on the X9 display. If "red", "blue", "green", "yellow", or "purple" is sent, the message will be displayed in the corresponding color and a custom reply will be sent from the X9 activity tracker to the phone app.

    I have also included a simple sketch demonstrating the super simple font.

    All files for examples can be found in the GitHub repository, including required libraries and application hex files which I compiled myself. If you have a hacked X9 you can immediately load my compiled application to quickly check out the demo. I am adding the actual example sketches to the project files as well.

    GitHub repository file directory:

    nRF5x-device-reverse-engineering --> X9-nrf52832-activity-tracker --> Firmware --> examples --> nrf52_X9Project_BLE_CHAT
    nRF5x-device-reverse-engineering --> X9-nrf52832-activity-tracker --> Firmware --> examples --> nrf52_X9Project_ALPHABET

    Nordic UART Bluetooth Serial app:

  • Intraoral Respiration Monitor - A Computer Inside Your Mouth!

    Curt White04/23/2018 at 19:06 0 comments

    A wireless full waveform respiration monitor worn entirely inside user's mouth (intra-oral) that streams data to a Web Bluetooth enabled web application. We built this by hacking the tiniest ARM based activity tracker we could find! 

    The device measures the air pressure, humidity and skin temperature inside the user's airway. In short, BME280 air pressure sensor + MLX90615 thermopile thermometer + hacked miniature nRF51822 based activity tracker mounted on an ultra-thin custom dental retainer. 

    We also spun this off into a separate Hackaday project with more detail, check it out.

  • The "Tingle" Gesture Recognition and Biofeedback Device For Compulsive Behaviors

    Curt White04/20/2018 at 03:31 0 comments

    The "Tingle" Gesture Recognition and Biofeedback Device is a project I'm working on at the Child Mind Institute. To put it very bluntly, it is designed to help kids stop compulsively tearing out their hair, a disorder called trichotillomania which is surprisingly prevalent. I built the prototype using the X9 activity tracker presented in this project.

    From the MATTER Lab website:

    As you are about to compulsively pull out your hair, bite your nails, or engage in some other body-focused repetitive behavior, you feel a tingle on your wrist. Then a notification is sent to an online dashboard. This information helps you to be mindful of your behavior as part of a behavior modification therapy, and helps your therapist monitor your progress. This is the rationale behind building the Tingle and applying for a patent. We have just run a pilot study and are preparing for a clinical trial.

    Prevalence of body-focused repetitive behaviors (BFRBs)

    Body-focused repetitive behaviors (BFRBs), symptoms of Obsessive Compulsive Disorder (OCD) and other conditions involving compulsions (e.g., Autism Spectrum Disorder) involve compulsively causing physical injury and/or damaging one’s physical appearance. These are among the most poorly understood symptoms; they are often misdiagnosed and undertreated. BFRBs include hitting oneself, biting, pulling out hair, skin picking and cutting, as well less severe but damaging behaviors such as nail biting, thumb sucking, and nose picking (Families & Health). These symptoms affect at least 5% of the population (Families & Health); hair pulling alone affects 1%, or about 3 million people in the US (Diefenbach, Reitman & Williamson 2002). BRFBs are highly comorbid. Studies have shown that as many as 70% of those with one BRFB will have another co-occurring BRFB (Conelea, Frank & Walther, 2017). While often impairing, affecting medical health and/or disfiguring, these symptoms are frequently reported but often not observed in clinical settings. This makes diagnosis, as well as treatment planning and monitoring, exceedingly difficult. To avoid pain and disfigurement, it is imperative to identify a reliable means to automatically identify and monitor BFRBs, especially outside the clinic setting. Clinicians need data on BFRB frequency and timing for the purposes of diagnosis, treatment planning and monitoring while patients need immediate, real-time feedback to make behavioral therapies more effective.

    The “Tingle” device

    To address this previously unmet clinical need, we have created a prototype for a wrist-worn device called the “Tingle” that can monitor and record BFRBs while also providing real-time (haptic) feedback (on the wrist) to the individual with BFRBs when they occur. The Tingle is the subject of U.S. Patent Application #15/816,706 filed January 26, 2018.

    Testing the accuracy of the Tingle device for detecting different simulated BRFBs.

    In a pilot study to establish the accuracy with which the Tingle can detect BFRBs in a controlled setting, we recruited 50 healthy, adult volunteers to wear the Tingle and repeatedly simulate 9 different behaviors (eating, smoking, thumb sucking, nail biting, nose picking, skin picking, and hair pulling from three locations). We just gathered the data and are analyzing the data now!

    Testing the clinical efficacy of feedback via the Tingle in therapy.

    This proof of concept leads to the critical next step of applying the Tingle to the clinical setting in which we will confirm the Tingle’s effectiveness in preparation for an FDA New Device Application and plan for commercialization. This will open the way for broad distribution in clinical practice as a diagnostic tool and to support the evaluation and implementation of pharmacological and behavior therapies for BFRBs.


    The Tingle is well-positioned to address the tremendous unmet need in the care of individuals with BFRBs...

    Read more »

  • Get More GPIO The Easy Way

    Curt White04/20/2018 at 00:28 0 comments

    If I couldn't add additional sensors to the X9 Activity Tracker it would be useless to me. To be perfectly honest, I don't even particularly like activity trackers. Unlike an Arduino, Teensy, ESP32 or ARM Cortex breakout board, hacked activity trackers don't provide convenient access to additional MCU GPIO for adding sensors etc. There is a simple solution: cannibalize GPIO from existing components.  I always remove the OLED for my own projects. I'd rather interact with devices using a mobile app or web application over Bluetooth. Bluetooth is the whole reason I find Nordic chips so appealing. Take a look at the below example of how I desolder the X9's OLED display to gain additional GPIO for sensors:

    The primary OLED GPIO (P14, P13, P12, P11) are really easy to access because there are nice big test pads to solder underneath the OLED ribbon cable. P15 is a little bit harder because you have to solder the place where the ribbon connected, but still no biggy. But what if you need more GPIO or want to keep the OLED? You can access P29 (heart rate detector photosensor) and P30 (touch sensor) by scraping off the solder mask from the appropriate traces and directly soldering a wire to the trace. You will want to isolate your connection to the MCU from supporting circuitry related to the original use of those GPIO. In order to do this, solder to the trace in a place where there is nothing connected between your solder point and the MCU (nRF52832), then cut the trace above your solder point.

    You can use this annotated, highly detailed composite microscope image of the X9 PCB (high resolution version in project files) and list of component pin connections to figure out traces you might want to solder into:

    • HR_LED_PIN            4
    • HR_DETECTOR       29
    • TOUCH_BUTTON    30
    • VIBRATE_PIN           8
    • BATTERY_PIN          28
    • OLED_CS                 15
    • OLED_RES               14
    • OLED_DC                13
    • OLED_SCL               12
    • OLED_SDA               11
    • OLED_LED_POW     16
    • OLED_IC_POW        17
    • KX126_CS                 24
    • KX126_SDI               19
    • KX126_SDO             20
    • KX126_SCL              18
    • KX126_INT               23
    • FLASH_CS                22
    • FLASH_SDI               19
    • FLASH_SDO             20
    • FLASH_SCL              18

  • "Thermo" Position Tracking Wearable Device

    Curt White04/19/2018 at 23:29 0 comments

    The "Thermo" position tracking device is a controller for VR/AR or any other situation where tracking a user's hand in 3D coordinate space might be useful. The Oculus Rift and HTC Vive virtual reality headsets both have 6DoF (Six degrees of freedom) position tracking controllers. They also depend on a camera or some other external device to achieve 6DoF hand position tracking. At the Child Mind Institute MATTER Lab we applied machine learning techniques to vast amounts of thermal imaging data and leveraged the results using a device worn on the wrist with a fairly sparse sensor configuration. We are attempting to achieve the capabilities of the Oculus and Vive controllers without any external reference point. This device was prototyped using the X9 Pro activity tracker - the exact activity tracker presented in this project.

View all 5 project logs

  • 1
    Get a X9 Pro Activity Tracker

    Aliexpress, Banggood, and Ebay are your best bet. Pricing will vary widely so it pays to look around.

    LINK1   LINK2   LINK3   LINK4   LINK5   LINK6

    NOTE: I have purchased many X9 Pro activity trackers. Some of them have a green PCB and some have a blue one. It doesn't make a difference for the purposes of this tutorial. The traces on the PCB are arranged a little differently but all the components are the same.

  • 2
    Cut Glue Between Translucent Plastic Cap and Metal Enclosure Body

    Use a hobby knife ("X-Acto" knife) to cut as much of the glue bonding the plastic cap to the metal body as possible. Getting a thin blade between the plastic and metal will gradually wedge the two apart. Take your time (I would budget at least 5 minutes) and work your knife all the way around the cap.

  • 3
    Lift Plastic Cap Off the Metal Enclosure

    Use a small screw driver or prying tool to carefully lift the plastic cap off the metal enclosure body. Take your time and work thy prying tool around the cap.

    Separate the cap and put it aside for now.

View all 12 instructions

Enjoy this project?



arthur_jordan05 wrote 07/19/2018 at 06:57 point

Came across another nrf52832 tracker that is even cooler maybe: it's the SMA Q2 or SMA-TIME

  Are you sure? yes | no

Curt White wrote 07/19/2018 at 14:36 point

That is cool, especially the OTA bootloader. Thanks for the heads up!

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flashcactus wrote 06/15/2018 at 10:03 point

Well, dude, this definitely makes my currently-abandoned project obsolete.
Great hack, congrats! Will probably be picking one up any time soon

  Are you sure? yes | no

Roger Clark wrote 06/07/2018 at 02:02 point
I word of warning to anyone thinking of buying a X9 Pro. I ordered 2 "X9 Pro"s from AliExpress, but they turned out to be "X9 Plus" versions, which look identical until I noticed that the display was not showing any colours except light blue. When I double checked the box, I realised they were not what I thought they were The X9 Plus does not have the Nordic nRF52 MCU, its got the old TI CC2541 MCU in it which is an 8 bit MCU not a 32 bit ARM processor like the nRF52 I've opened a dispute through AliExpress and I'm hoping they will give me a refund, but I had already accepted the order as visually it seemed OK, and I didnt realise there were more than one type of X9, (which look very similar)

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pelrun wrote 06/03/2018 at 05:47 point

I've successfully reprogrammed the X9 over bluetooth using the nRF Connect app on a phone. 

Note: it's *really* easy to flash something and have no way to get back to the DFU mode. So I absolutely recommend having an opened watch connected to a debugger to do primary development. When DFU is working on that, then you can try sending it to an unopened unit.

The firmware on my X9 is built using SDK 11.0.0, the S132 2.0.0 softdevice (FWID 0x81) and the legacy bootloader. This last part is why DFU is possible without needing the private key (you can replace it with the SDK 12+ secure bootloader if desired later.)

So here's the trick: build a distribution packet using nrfutil (use the legacy 0.5.3 version), then *unzip* it to get the application .hex and .dat files. Send them to the phone, and flash the .hex file using nRF Connect. When it asks for the init packet, give it the .dat file. This works where just giving the .zip file fails, even though the contents are identical.

Edit: ugh, spoke a little too soon. I *have* had it work, but it looks like massive luck. The bootloader jumps to the application almost instantly, making it a race to get the DFU happening in time. Will keep poking at it.

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prestegaard9 wrote 05/31/2018 at 06:57 point

Do you have a suggestion on a cheap SWD capable programmer: J-Link, Black Magic Probe etc.

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Curt White wrote 06/17/2018 at 07:48 point

You can create your own Black Magic Probe using an STM32 'Blue Pill' board which can be had on Ebay for $4 (see project GitHub repository README). Generic/clone J-Link programmers can be had on Ebay for $12. 

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Danin wrote 05/17/2018 at 21:32 point

Fantastic project, as soon as I saw it I picked up a pair and a programmer. I've question and I'm sorry if you have addressed it but I'm on mobile and don't want to forget to ask - would there be any interest in this platform being ported to the PlatformIO suite? I think it would benefit greatly from that, and would love to see it there.

  Are you sure? yes | no

Curt White wrote 05/17/2018 at 23:07 point

In terms of PlatformIO, anything that supports Nordic nRF52832 and nRF51822 will work. There are already people using Sandeep Mistry's Nordic ArduinoCore on PlatformIO, so in that sense PlatformIO already supports these hacked activity trackers. You can use ARM Mbed as well, and then there is always the Nordic SDK. 

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arthur_jordan05 wrote 05/10/2018 at 16:19 point

Very interesting project, thank you very much for sharing. I wanted to get started with nRF52832 in the Arduino enviroment for some months now and this got me going. This X9 pro thing is made surprisingly well.

One question: where can we get the KX126_SPI.h and ssd1331 library? I assume the latter is by lexus2k on github, but I think it needs some mods to run on NRF52...

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Curt White wrote 05/10/2018 at 20:36 point

The KX126 library is in the Web Bluetooth X9 example on GitHub ( ).

X9 --> Firmware --> examples --> nrf52_X9Project_WEBBLUETOOTH

As you say, I use lexus2k's library for the SSD1331 OLED driver. I have been using the primitive line drawing feature - this works more or less out of the box with the nRF52/nRF51. I can get the first/top memory page working with the actual graphics library, but I haven't been able to get the rest of it working. I tried vertical addressing mode but that just gives me garbage. Making any of the Arduino SSD1306/SSD1331 OLED libraries work with the nRF52 is going to require some time and effort. I used the line drawing function to draw a rough bitmap in the OLED example by iterating across it pixel by pixel. I'm going to create a simple text writing library and example for the X9 using the same technique. If you want to take a crack at porting lexus2k's library to the nRF52 that would be great.

Note: I just collected all the libraries used by the X9 examples and nRF52 based Hackaday projects in a single folder: common --> libraries

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arthur_jordan05 wrote 05/11/2018 at 07:03 point

Thank you for the quick reply and the great info! I just thought: can you get the Adafruit nRF52 Frather or official Arduino Primo core running on the device? Sure, they seem to work via bootloader upload but maybe one can get hold of the hex file somehow. I'm also wondering whether either of those cores has an upload function via J-Link programmer through the Arduino IDE. At least for burning the bootloader this seems to be the case with the Adafruit core.

In case you're interested in additional physiological parameters: I've also hacked a cheap blood pressure monitor and pulse oximeter in the past.

Throughout the past year the U80 "Smartwatch" was my wearable dev platform of choice. I was intrigued by the cap touch screen and designd a custom ATSAMD21-based board with HM-11/Simblee-based bluetooth, MPU9250 and BME680 to fit into the enclosure. At the moment I'm working on the option that  the developer can choose between different screens like for example Sharp MemLCD or a 1.3'' IPS tft. Modifying graphics libraries can be quite time-consuming as I'm learning at the moment. As soon as the newest version is working, the design will be published.

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Curt White wrote 05/11/2018 at 18:40 point

Adafruit's core is directly based off Sandeep's core (see "This core is based on Arduino-nRF5 by Sandeep Mistry, which in turn is based on the Arduino SAMD Core." at bottom of README for ).

My impression is that the Primo is more or less dead ( ).  The Primo did support low power clock which would have been very handy. Apparently there are some licensing issues with the Nordic SDK that are complicating implementation of low power clock/RTC: In terms of supporting the Arduino IDE and Arduino style minimalist C there is also Red Bear. Although Adafruit has built some interesting tools to go along with their core, Sandeep's core is still ahead of the game in terms of supporting Nordic SDK features. 

You have been doing some excellent hacking. I am interested in learning more about your work with the U80. I would love to have a look.

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arthur_jordan05 wrote 05/13/2018 at 15:53 point

The work on the U8 is a re-design of Dan Geiger's approach ( The amount of circulating U8 clones with significant differences is enormous. Many of them have the touch controller on the main PCB which is the unusable variant. The useful ones have it on a flex-rigid assembly and are usually sold as U80 (for examle by "NAIKU"). The touch controlles is a "BL6280" for which its I2C communication had to be reverse-engineered first, which I have done here:

Version 1.1 works ( and 1.2 is coming soon.

The good Arduino core support was the reason I chose the ATSAMD21 as the main processor with bluetooth offloaded completely. A chip with USB bootloader is very very handy for a wearable made for hackers and developers. Its low power and RTC options are also easily accessible (I think a watch-like device needs to have those features.. The current board revision will have a simblee as a BT device which can be programmed via the ATSAMD chip...

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Curt White wrote 05/14/2018 at 05:35 point

This is excellent! Anyone reading this thread who is interested in hacking wearables should check out those links. I ordered a couple of the $10 U80 smartwatches. Are you going to sell those ZeroWatch boards on Tindie or the like?

Given the opportunity, people should certainly take a crack at building your U80 replacement board so they can enjoy all of your work - but - if unable to get one of your boards it should be possible to wire up a hacked nRF51/nRF52 activity tracker inside a hacked U80 by just soldering a few wires between the two. That would provide the benefit of the 128x128 ST7735 TFT display and, with your code, the BL6280 touch interface for less than the price of a movie ticket.

The ATSAMD21 Arduino cores/wrappers has a definite advantage over nRF5x Arduino cores/wrappers when it comes to RTC. In some cases I've handled this with sensor interrupts (think pedometer) to wake up the MCU from low power sleep. This is useful for data logging but it won't keep the time. Fine grain power management requires direct use of the Nordic SDK.

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arthur_jordan05 wrote 05/14/2018 at 10:44 point

 I'd certainly make and sell a couple of those boards on tindie if my time was not as constrained as it is. Maybe some day...There should be many people out there who enjoy SMT soldering. Luckily, nowadays it's quite easy with cheap PCB and stencil services. But you're right: for the software folks this would be a nice product. 

I've recently discoverd these screens:,searchweb201602_5_10320_10152_10321_10065_5722917_10151_10344_10068_10342_10547_10343_5722817_10322_10340_10341_10548_5722617_10193_10696_10194_10084_10083_10618_10304_10307_10302_5722717_10059_5711217_308_100031_10319_10103_5722517_10624_10623_10622_10621_10620_5711317-normal#cfs,searchweb201603_25,ppcSwitch_5_ppcChannel&algo_expid=3c49e8fc-94b3-4ea2-85f0-a0c4d1d26575-4&algo_pvid=3c49e8fc-94b3-4ea2-85f0-a0c4d1d26575&transAbTest=ae803_2&priceBeautifyAB=0

They're a bit smaller but the resolution, viewing angles and price are great! They should be a nice alternative to the ST7735...Back to the SSD1331 once again: so porting of the libraries to nRF52 is not simply done by porting the SPI writecommand() and writedata() functions? Haven't tried it myself yet.

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Curt White wrote 05/14/2018 at 23:29 point

In terms of difficulty porting libraries.... only one way to find out ;) I'll be sure and spread the work about your project and I'll let you know if I come up with anything on the U80.

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arthur_jordan05 wrote 05/18/2018 at 07:23 point

You`re right, I forgot :). Thank you. I'll definitely keep on hacking with the X9 and following your projects. The machine learning part will be very educational for me too.

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Duke Circuit Co.,Ltd wrote 05/03/2018 at 01:28 point

It's uncomfortable to put a device in the mouth,any other way to replace it?

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Curt White wrote 05/09/2018 at 18:42 point

The Intraoral Respiration Monitor is a product of low cost rapid prototyping so with more development time and resources the form factor should be significantly improved. There have been some interesting tooth mounted devices emerging recently ( ). It is possible this device could be significantly miniaturized to the point where it could be tooth mounted. That would be an interesting project but not the kind of thing I imagine would hit the market and actually help real people anytime soon (which is what I'm most interested in). I think the combined use of skin temperature and air pressure sensors inside of the mouth is promising for fine grain respiration monitoring regardless of form factor. If I were to try and modify this project for an easy to manufacture and immediately comfortable form factor I would probably go with something along the lines of a mouth thermometer. I could also see integration into Tracheal intubation for surgery or intensive care.

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Jim Shealy wrote 04/27/2018 at 01:30 point

Out of curiosity, do you know much about integrating apps/code with the x9 via bluetooth without modification? 

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Curt White wrote 04/29/2018 at 01:18 point

What you are referring to is the FOTA (Firmware Over The Air) DFU (Device Firmware Update) service. This is indeed a capability that the Nordic Semiconductor nRF52832 and nRF51822 SoCs have: . I have not succeeded in getting DFU to work with any of the activity trackers I’ve hacked. To be perfectly honest, I haven’t tried that hard – all my applications require extensive modification. Roger Clark tried to get DFU working on a hacked nRF52832 activity tracker, his blog post contains information you might find useful:

Let me know if you get it working, that would be very interesting

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pelrun wrote 05/30/2018 at 10:10 point

I've been reverse engineering the default firmware on my X9 for the past few days; I've confirmed it's using a lightly modified version of the dfu bootloader example from the 11.0.0 nRF SDK. Good news is that is before the secure bootloader was released! So theoretically uploading new firmware to an unopened watch should be possible, but I still need to do some work to figure out exactly what needs to be sent.

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James Hall wrote 05/07/2018 at 12:24 point

I'm interested in this too Jim, let me know if you figure it out. I'm sure there are some uses these can be put toward without requiring hardware modifications.

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Tom Meehan wrote 04/24/2018 at 21:49 point

Amazing work, very inspiring - so much so that I just ordered an X9 and can't wait to test it out.

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Curt White wrote 04/25/2018 at 01:47 point

Thanks! I plan on posting more sample sketches for the X9. With any luck I'll have a demo for PPG heart rate detection by the time you get your X9.

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Tom Meehan wrote 04/25/2018 at 23:18 point

That's great - the PPG heart-rate detection is what initially interested me. Quick question - would the SEGGER J-Link EDU Mini - JTAG/SWD Debugger that Adafruit sells work for programming?

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Curt White wrote 05/21/2018 at 03:14 point

Yes, that will work just fine. 

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Eric Morgan wrote 04/22/2018 at 19:05 point

This is great, just ordered one of the X9 watches. What kind of range do these get with Bluetooth?

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Curt White wrote 04/22/2018 at 19:23 point

Bluetooth range is solid, comparable to a FitBit. Some models have very cramped PCB trace antennas but the X9 and N68 are fine. I did run into one situation where Bluetooth range became problematic. I built an intraoral respiration monitor using a small nRF51822 activity tracker wherein the entire device resides inside the user's mouth. I cut the trace antenna at the nub and soldered a little solid copper wire antenna that can stick out of the user's mouth when necessary. Works just fine.

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Curt White wrote 04/20/2018 at 04:16 point


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gerardwknight wrote 04/20/2018 at 02:36 point

Brilliant work, this is inspiring stuff! I hope you win, its a great field of research you have chosen, it could help many many people in the future.

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