[HN Gopher] Building a T1D smartwatch for my son from scratch
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Building a T1D smartwatch for my son from scratch
Author : andrewchilds
Score : 531 points
Date : 2025-01-28 16:33 UTC (2 days ago)
(HTM) web link (andrewchilds.com)
(TXT) w3m dump (andrewchilds.com)
| mattboyle wrote:
| This is really really awesome. I applaud you.
|
| I had my own project trying to achieve a similar outcome to you,
| I wrote about it here: https://www.bytesizego.com/blog/keeping-
| alive-with-go. Your approach is much more hardcore. I hope you
| find a path to make them available to more folks.
|
| If there is anything I can do to assist you please let me know!
| andrewchilds wrote:
| Thank you! I remember reading your article! Even though you
| have to maintain it, it's actually way better than what's
| commercially available since you actually have control over
| _how_ you're alerted, not to mention when to escalate to
| friends or family. I've heard Type 1 kids going away to college
| is a huge source of stress for parents/caregivers for this
| reason - Sugarmate and the SugerPixel help with this but it
| still feels like a huge problem (a Type 1 sleeping through a
| low).
| bdcravens wrote:
| This is great. I do watch my Dexcom on my Apple Watch, but
| there's times I just want the number, ASAP. I was hoping it'd
| talk about eliminating the need for the iOS app ("...where he
| shouldn't have to run around with a phone strapped to him...")
| but it sounds like it's just not possible to avoid at least
| periodic polling.
|
| Reading through the product development, I'm curious why you
| didn't use a dev kit like the Pine Time?
| (https://pine64.org/devices/pinetime/) I bought one a few years
| ago and it's just been sitting in the box, waiting for a project
| to build on it. I may take a stab at something similar.
| andrewchilds wrote:
| Thank you! It should be possible now with the G7 to have the
| watch pair directly with the sensor. We're still on the G6.
| Agreed that would be much better than having to go through the
| iOS app and up to the cloud.
|
| Honestly I don't remember why I ruled out the PineTime. I
| purchased a Bangle.js and while it's very small, it seemed very
| limited in what I could do with it. Of course with the Pebble
| announcement yesterday, that might change things.
| roywashere wrote:
| PineTime is nice and cheap and does a little BlueTooth. It's
| easy to flash your own firmware to it; I think it might have
| been an option.
|
| That said, Pine64 does not do a whole lot of work on their
| platform and I guess a lot of people are wanting _more_. It's
| a simple watch and for what it does and costs it's great. If
| you think you'll get an open source Apple Watch, you're going
| to be disappointed.
| nknealk wrote:
| The G7 pairs directly with an Apple Watch and acts as the
| primary sync device. Unlike the G6, you don't get null readings
| displaying on the watch until you open the app. I have the
| dexcom widget on my Apple Watch series 10 with a G7 paired with
| direct to watch and it always displays the current reading
| andrewchilds wrote:
| That's great to hear that direct-to-watch pairing leads to a
| reliable reading. That's a big improvement over where things
| were a year ago. I am surprised that the watch becomes the
| primary sync device instead of the phone, but maybe that's
| not actually a problem in most situations.
| bdcravens wrote:
| I wore the G7 briefly, but switched back to the G6 because
| the long-awaited iOS integration for my pump (Omnipod) only
| supports the G6 at this time. (otherwise I have to carry
| around a separate device, which is essentially a dumbed down
| Android phone)
| lagrange77 wrote:
| Very cool!
|
| I love the texture of the enclosure. I guess that's not possible
| with an FDM printer, right?
| andrewchilds wrote:
| Thank you, I do too! I wish it was possible to leave it
| uncoated, but it develops a worn look pretty quickly. Printing
| MJF through Fictiv was pretty cheap, especially if you don't
| need a rush delivery.
| ilynd wrote:
| Did you ever look into an e-ink display?
| andrewchilds wrote:
| I did, but they're surprisingly expensive, and a black-and-
| white display isn't all that exciting for a kid. An always-on
| display would however be perfect for this use case though.
| ilynd wrote:
| Ah - unfortunate. I'm a type 1 diabetic myself, maybe someday
| I'll get round to doing something like this. Looks pretty fun
| wanderingmoose wrote:
| First of all -- awesome!
|
| Second, if you aren't aware or in case others are interested, the
| main dev from the xdrip project released a custom watch as well:
| https://bluejay.website/ There are some posts on reddit from the
| dev. (for others -- the watch is available for purchase, and
| allows integration w/ xdrip).
|
| Third --> we've come a long way in a short time. When I was
| diagnosed I had to collect urine samples and drop chemical
| tablets in them to see how much glucose was present. And now you
| are building an custom solution tailored to your and your son's
| needs...wow. I really applaud you.
|
| Fourth --> I'm hoping the new discoveries in the synthetic
| signaling w/ insulin will finally give us a biological solution
| and the tech will no longer be necessary. Here's to hoping!
| andrewchilds wrote:
| Yes! The BlueJay watch project is amazing, very encouraging to
| see that he was able to connect directly to the sensor from the
| watch with the latest version. Totally agree with you - one of
| the biggest sources of hope for us in those first few weeks
| after he was diagnosed was knowing how far the tech had come,
| and how many huge advancements were in the pipeline.
| martyz wrote:
| Incredible work - so cool to see Dad being a tech and health
| champion for their kid. T1D is so tough and to have such
| incredible support is great to see.
| jablongo wrote:
| Nicely done - it's crazy that you could do this solo and the
| multi billion dollar device makers haven't been able to do it in
| many years. Would be a nice peripheral for them to sell along
| with their CGMs (instead of those old receiver devices that
| everyone stopped using in favor of smartphones). Wishful
| thinking, but maybe try to talk to Abbott or Dexcom to see if
| they will fund another open source production run of these?
| Output to them could be a report/collection of user feedback to
| help them w/ product strategy...
| FL410 wrote:
| This is really cool. Having gone through some of the same
| challenges for hobby projects myself (learning Fusion, learning
| to make a PCB, learning to make the 10th revision of the PCB),
| you're being quite humble - each one of these things is _hard_
| with a steep learning curve.
|
| Awesome work!
| DoingIsLearning wrote:
| Hi Andrew, amazing work and done for the best of reasons!
|
| I see you are replying in the thread, in your closing notes you
| wrote:
|
| > I would not have been able to get past the initial stages
| without ChatGPT.
|
| One of the coolest uses of LLMs for me is indeed exploring a
| problem domain where I am not a subject matter expert.
|
| The problem is if it leads you down a dead end or hallucinates a
| solution. Then, at the edge of your knowledge, you actually have
| a very small foothold with which to challenge these chat replies.
|
| Did you also face this on the more HW 'heavy' part of your
| project? Any tips on how to navigate terra incognita with LLMs?
| andrewchilds wrote:
| Lots of trial and error! ChatGPT was sometimes helpful with
| hardware and electrical engineering questions, sometimes not.
| Since I would need to wait a while for the next version of the
| PCB to show up, it was important to check and verify things,
| but it did help me find my bearings and develop a general
| understanding of concepts. I learned a lot from open-source
| reference implementations from similar projects. I was able to
| get a lot of help while learning the software as well - in this
| case Fusion 360 and KiCad - though sometimes ChatGPT would
| invent a setting that should be there but isn't. As long as you
| have a rapid feedback loop where you're testing and verifying
| what it's telling you, I don't think you'll ever find yourself
| very far off course.
| summermusic wrote:
| > I learned that One Does Not Simply put glass in front of a TFT
| display. It will look like a first-generation, low-budget Android
| phone if you do.
|
| Do you happen to have any before-and-after photos of what this
| looked like, and more details on how your tortilla press DIY
| method works? I recently received a little hackable music player
| device with a TFT display that looks kind of bad and I wonder if
| this is something I can do to make the display look good.
| andrewchilds wrote:
| The process was applying steady pressure to the TFT display ->
| OCA film -> glass, sandwiched between soft rubber, for about a
| minute. However you need to do a decent job applying the OCA
| film in the first place - there are youtube videos that show
| how to do it.
|
| I probably wouldn't recommend what I did in your case - it's
| easy to go too far and break the glass, and I'm not sure if
| what's wrong in your case is due to the OCA film in between the
| display and the glass.
| antonok wrote:
| FWIW, there is an alternative to OCA film that's slightly
| easier to apply in small quantities without specialized
| hardware - it's called LOCA glue (i.e. Liquid OCA).
|
| I'd definitely recommend that if you're just assembling less
| than, say, 10 screens.
| RandomUser4976 wrote:
| T1D parent here. My 11yr old has T1D. We use SugarPixel and this
| watch you've built would be amazing to have. Great job! We need
| more people like you
| pigeons wrote:
| Thank you
| Projectiboga wrote:
| Maybe look at the new openpebble that has opensourced the Pebble
| Watch tech.
| bluesounddirect wrote:
| Andrew : Amazing i always love to see the creative T1D projects.
| i home one day we have a biological cure . Back when the pebble
| watch was still a relatively new product. someone had an app for
| it to be a remote display for the dexcom. it required an external
| nodemcu based microcontroller to be a middleman, but what it did
| well was run for days off the battery. my wife used one for a
| long while; the take aways were black and white e-ink displays
| saved tons of power . pebbles os was good a power mgmt and it's
| limited features made devs stick yo core functionality not look
| for new cool extraneous add ons .
| LeicaLatte wrote:
| Awesome project! Direct sensor connectivity is an interesting
| approach. Skipping the phone app is a big win.
| K0balt wrote:
| Great project!
|
| Idk if this might be useful or not, but there is a smartwatch
| platform (bangle.js 2) that uses the NRF52840 chip (extremely low
| power, solid BLE support, works with Espruino, micro python,
| arduino, and other IDEs) battery life is around a week, depending
| on what you run, of course.
|
| The watch includes an always-on color transflective display, GPS,
| accelerometer , barometer, haptic motor, compass, sound,
| touchscreen, etc.
|
| You could do firmware from scratch or you could use the onboard
| OS and write the program as an App.
|
| The watch isn't distracting, unless you install stuff on it to be
| distracting. I think your program might be able to be written as
| a "watch face" so that it would not have to be launched from the
| launcher, but you could also write firmware for the watch so that
| it just does what it does period.
|
| It seems to me like this does everything you want, maybe?
|
| I bought a couple of these (2?) years ago for my kids to program
| on, they have been great!
|
| https://banglejs.com/
| andrewchilds wrote:
| Thank you! I did actually buy a Bangle 2 early on in the
| project; I was impressed by the Espruino project and by how
| small the watch is, but it seemed slow to wake, and the screen
| was tiny, dim and had a lot of light bleed. But you're making
| me think I should take another look. Very cool that your kids
| are programming their own watches!
| K0balt wrote:
| Yeah, the transflective display is not great, but the power
| usage is nil when the backlight is off, which is nice. E-ink
| might be even nicer.. but the price is a major stumbling
| block for most form factors.
|
| The pebble might be a good option though, not only is the os
| now open sourced but there is apparently someone trying to
| build new watches.
|
| Once you get out of the hobby space, Hardware is a tough
| business, and there are a lot of people that would benefit
| from a solid solution that won't be up for tinkering.
|
| You might also find that there are Chinese manufacturers with
| white-box watches that might be running common chips like the
| nrf52840/832. I certainly see a lot of apparently identical
| smartwatches around 30 dollars that are marketed under
| different brands. Those might be a better direction if you
| are looking at a broad market.
|
| OTOH, once you get away from the supportive and nurturing
| maker environment most of the fun will leak out, so depending
| on your motives, you might want to stick to your solution -
| which looks pretty great to me, even if it might not be as
| simple to scale production.
|
| Best of luck with whatever direction you are looking at. By
| the way, you might try a resin printer if you are going to be
| doing any production in house. For larger multiples of small
| parts they are crazy fast and the finish is pretty great.
| andrewchilds wrote:
| Thanks! Yeah, it's odd to me that there are so many cheap
| Apple Watch clones on Aliexpress with nice AMOLED displays
| and sensors galore, but nothing hackable, nothing with an
| e-paper/MIP display. I feel like they would make way more
| $$ if they made one that was hackable? Lilygo.cc has done a
| lot of work on open hackable watches, but they're big and
| not water-resistant.
| hommelix wrote:
| Another interesting watch is zswatch. It uses a nrf mcu as
| well. https://github.com/jakkra/ZSWatch
|
| https://www.youtube.com/watch?v=MmCzV0jV9hs
| earleybird wrote:
| It's great to see awesome work like this making a difference.
|
| Scott Hanselman has blogged[0] and spoken at some length on tech
| and living with T1D going back to 2002.
|
| [0] https://www.hanselman.com/blog/category/diabetes
| Twirrim wrote:
| > First, the Apple Watch (like all Apple products) is too much
| device for a kid. It ships with so many shiny features and apps
| and notifications.
|
| It feels like a bit of an under-served market. T-mobile has a
| smart watch that you can lock down completely during school
| hours, which we've done with one of my kids (we're avoiding
| smartphones for now, and she's strangely quite happy with that, I
| honestly expected more push back.)
|
| Unfortunately, it wouldn't work for T1D situation. I've a
| relative with T1D and it's been exciting seeing the technology
| change over the ~10 years since they got their diagnosis.
| Bug9519 wrote:
| I just wanted to say that's a pretty awesome project, and it's
| great that you were able to do this for your son.
| coder543 wrote:
| Wow! This is some phenomenal engineering!
|
| > Another area that stumped me is how to shut the power off 100%
| on the device, so that it can remain "off" for weeks or months.
|
| This is actually a pretty solvable problem...
|
| https://circuitcellar.com/resources/quickbits/soft-latching-...
|
| Then the microcontroller can choose at any time to completely
| shut off the entire circuit (including itself), and extremely
| little power will be consumed until something (like a button)
| completes the power-on circuit again.
|
| For ease of prototyping, there are off-the-shelf units you can
| play with: https://www.sparkfun.com/sparkfun-soft-power-switch-
| jst-2mm....
|
| Some more advanced soft power switch circuits (like the SparkFun
| switch) also include the ability to forcibly power down a
| misbehaving device by holding down the button.
|
| The design used in the SparkFun switch also allows your
| microcontroller to know if the button is pushed while the device
| is running, so you could imagine repurposing your existing button
| to also restore power to the device if the device is off, and
| still retain the existing functionality for cycling through watch
| faces. Then, either the device could automatically shut itself
| off after a period of inactivity or when the battery gets too
| low, or the user could click and hold the button for some number
| of seconds to turn the device off completely that way.
| andrewchilds wrote:
| This is exactly what I was looking for! I had a foggy idea of
| using a MOSFET and the button to close/open the circuit but I
| needed something like this to show how it all fits together.
| Thank you!
| coder543 wrote:
| No problem. I haven't had a chance to do anything hardware
| related for a long time, so it's fun to think about hardware
| problems again.
|
| On the topic of extending battery life mentioned in the
| article, one relatively straightforward thing to investigate
| is simply reducing the processor clock speed. Your
| application probably doesn't need to run at full tilt. I
| think there is a function called setCpuFrequencyMhz -- I
| think it only works with a few specific frequencies, but the
| lower the frequency you can pick (while still keeping up with
| your application's needs), the less power the system should
| consume while awake.
|
| Of course, you want to be putting the processor to sleep
| between updates anyways, and there is a trade off between
| sleeping more (which means running the processor faster so it
| can sleep sooner, "race to sleep"), versus the inefficiency
| caused by running a processor higher on the
| frequency/efficiency curve, so there might be an optimal
| frequency that isn't the lowest or the highest possible
| option. It's something that would need to be measured.
|
| Just some thoughts! It might not make a big difference if the
| processor is already sleeping most of the time, but I figured
| I would mention it as something to try.
| bbayer wrote:
| Another alternative is to use ESP32's deep sleep mode. You can
| tell ESP to sleep until some event occurs. There are many
| options for waking up the microcontroller.
|
| https://docs.espressif.com/projects/esp-idf/en/stable/esp32c...
|
| It uses little power, so standard 18650 battery could last
| years with single charge.
|
| https://www.programmingelectronics.com/esp32-deep-sleep-mode
| awjlogan wrote:
| ESP's deep sleep is not great - the datasheet for the C3 says
| 5 uA. That's an order of magnitude above low power
| microcontrollers (e.g. ATSAML), and two orders of magnitude
| above an ultra low power timer. Not horrendous, but higher
| than I'd prefer for a tiny watch battery.
| andrewchilds wrote:
| The ESP32-S3 spends most of its time in deep sleep, only
| waking up for about 5-10 seconds every 5 minutes. The problem
| I ran into was that not just the ESP32-S3, every component on
| the board (the accelerometer, the haptic motor driver, the
| LiPo battery charger, the 3v3 LDO) has a some constant,
| minimum (quiescent) current draw. And even how your resistors
| are configured (pullup or pulldown) and their resistance
| values contributes. To diagnose it, I would need a precision
| measurement tool like a ($1k) Joulescope
| https://www.joulescope.com/products/js220-joulescope-
| precisi... and probably a significant amount of time.
| msandford wrote:
| I had this problem on a low power design. We were making an
| industrial temperature sensor for something that moved and
| we needed to run on battery.
|
| What I ended up doing was using a second voltage regulator
| with an enable pin for all the accessories. When the MCU
| wakes up it turns power on to the accessories and waits for
| things to stabilize, maybe 1ms or so. Then it does what it
| needs to do and before going back to sleep turns all the
| accessories back off.
|
| Costs you a few extra parts and a second voltage bus and
| the hassle of programming but it turns "small quiescent
| draw" into essentially zero. Maybe the regulator has a bit
| of leak but it should be pico amps or less.
| awjlogan wrote:
| Wait until you look at the leakage current of capacitors..!
| _Very_ poorly specified, if at all, and can actually swamp
| the consumption of active components in these low or sub-
| microamp situations. The dual voltage rail that msanford
| described is the way to go here, gate as much as you
| possibly can and really focus on reducing the duty cycle.
| davidhyde wrote:
| I have also recently been through the same steep learning
| curve you have and the following worked for me. Reading
| spec sheets is fine but nothing beats measurement if its
| feasible. I built a custom PCB with all the power pins for
| all the peripherals broken out so I could put an ammeter in
| series with each of them individually. Then I used Nordic's
| inexpensive power profiler kit 2 (search for Nordic PPK2 -
| its under $100). Really decent specs at 100kHz sampling
| rate and 100nA resolution - you connect it to a PC to see
| the charts. I also bought my own resin 3D printer. They are
| so cheap these days and it helped with iterating on designs
| and not having to wait days for things to arrive. PS, great
| post, loved it.
| pipe01 wrote:
| I recommend the [nRF PPK
| II](https://www.nordicsemi.com/Products/Development-
| hardware/Pow...), it's (relatively) affordable and most
| likely would dl the job just fine for you
| adrianlv512 wrote:
| Here's a nice video featuring the product:
| https://www.youtube.com/watch?v=GqmnV_T4yAU
| adrianlv512 wrote:
| Here's a nice write-up where power consumption is measured
| using a voltmeter: https://peppe8o.com/raspberry-pi-pico-w-
| power-consumption/
| eclipsed0x01 wrote:
| This is extremely cool!
|
| Also sadly it'll get 10 times less upvote than making your own
| laptop from scratch because it's not done by a teenager.
| djyde wrote:
| Wonderful. I'm interested in learning about circuit and PCB
| design. What would you recommend as the best introductory
| resources to get started?
| andrewchilds wrote:
| I would start with breadboards and modules from SparkFun or
| Adafruit. You can mock up a lot of functionality without
| needing to solder anything. If you get to the point where
| you're ready to jump into PCB design, check out the
| /r/printedcircuitboard wiki:
| https://www.reddit.com/r/PrintedCircuitBoard/wiki/index/. You
| might be able to find similar projects that have been posted
| and critiqued there already. SparkFun and Adafruit both publish
| their schematics/PCB layouts. I recommend KiCad for your
| PCB/schematic software - there are plenty of KiCad tutorials
| and guides on Youtube. Have fun!
| HeyLaughingBoy wrote:
| Assuming you mean digital circuitry (99% of what's built
| today), I second the Adafruit recommendation. Sparkfun has good
| stuff but their focus is more on experimenters whereas Adafruit
| focuses on education. Their tutorials are very well done, and
| their hardware is much better "polished" than Sparkfun.
|
| I point out to people that it's clear that Adafruit is
| noticeably more expensive than the cheap stuff on amazon, but
| the fact that you can buy something from them, follow the
| tutorial on it and basically expect everything to work right
| off the bat makes the cost worth it. Even as a professional
| embedded developer, I go straight to them when I need to build
| a prototype and don't want to waste time faffing around.
| the_arun wrote:
| This is a great project.
|
| > They don't fund consumer products like this, but we agreed that
| the most plausible path to market is the open-source route,
| potentially turning it into a more general-purpose Pebble
| successor.
|
| Do you mean Kickstarter?
| 1f60c wrote:
| The number of skills one has to master for a project like this is
| just mind-boggling, and the part about the tortilla press made me
| laugh out loud. A labor of love in the most literal sense!
|
| That said, I would feel pretty nervous about actually selling
| these, as I wouldn't be surprised if it is legally considered a
| medical device.
| Chris2048 wrote:
| > I wouldn't be surprised if it is legally considered a medical
| device
|
| Couldn't you just include a disclaimer that it isn't?
| grahar64 wrote:
| My T1D son is 4.5yo, I book marked this page so that in a couple
| years I can read it a build him something that is (hopefully)
| just as cool. Unless I can buy it off the shelf...
| verytrivial wrote:
| I'm going to buck the trend and say this is an excellent idea,
| but it should absolutely NOT be used for its indended purpose. If
| OP wants to track his own insulin levels, fine, but to put DIY,
| uncertified, learn-as-you-go medical monitoring device on someone
| else, let alone _your own son_ is f*cking bonkers.
| tronicdude wrote:
| You have no idea what you're talking about.
|
| For T1Ds, you pretty much constantly have to monitor your blood
| glucose level. I used to use a Pebble for this, now I use an
| Apple Watch. The Apple Watch backgrounds the monitoring all the
| damn time, so I have to click multiple buttons and wait to see
| my blood sugar, when the number is immediately available on my
| phone (the watch didn't used to be this bad). The entire point
| of this hardware project is eliminating that latency.
| unxmaal wrote:
| xDrip4iOS has recently updated its Apple Watch app to have
| screen complications that show near realtime blood glucose
| levels.
| 392 wrote:
| Plenty of folks out there can't afford any treatment. This kid
| has it seems every form of treatment known to man and his dad
| is trying to make it more convenient for him, with the added
| benefit that this may make it cheaper/easier for the rest of
| the world. His level of risk tolerance improves the world and
| will cause his son no problems, while also avoiding learned
| helplessness.
| easton wrote:
| It's just calling APIs on the actual monitor, right? Or a
| service that listens to the monitor?
|
| Feels like low risk unless the watch gets out of sync (but easy
| enough to change the code to stop the watch from showing old
| data if that happens).
| cs02rm0 wrote:
| I don't see any issues with it as an additional measure, such
| as when playing sport as mentioned.
| andrewchilds wrote:
| Just to clear up the confusion here: there's basically no risk
| to this device. It's not inventing numbers on its own. It's
| simply a secondary display to the same data that's on the
| phone. The phone alarms are still there, and can't be disabled,
| not to mention the insulin pump, which also alarms
| independently.
| lloeki wrote:
| So AIUI rephrased differently it allows finer grained
| management _before_ the all hands on deck full tilt red alert
| alarms go blaring?
| andrewchilds wrote:
| Exactly right!
| HeyLaughingBoy wrote:
| Calm down. I've been building medical device software for close
| to two decades and the level of engineering in this device is
| at least what I see on multi-million dollar projects that are
| going for FDA approval.
|
| Medical Design process basically exists (oversimplifying of
| course) because the engineers are not the users. It's entirely
| possible for one person to build something that far exceeds the
| quality and performance of an off the shelf device simply
| because they care to do a good job and have constant feedback
| on how it works.
|
| There's a lot to be said for scratching your own itch!
| cs02rm0 wrote:
| I really have a soft spot for engineering that improves health
| management or outcomes, it never feels to me as though it gets
| the investment it warrants. Kudos, hope you get the funding.
| wnolens wrote:
| > I didn't have an OCA laminator, but you know what I did have? A
| cast-iron tortilla press.
|
| Haha. Great read. And aesthetically it's sweet as well. I wish
| your son accurately tracked and lasting health. He has an amazing
| dad to lean on!
| qq66 wrote:
| And to think, you could have done this in software if you had the
| right to push your own firmware to your Apple Watch.
| raminf wrote:
| Awesome work building it all from scratch!
|
| Hate to be that guy, but was using something hackable like a
| PineTime (https://pine64.org/devices/pinetime/) and doing a
| direct BLE connection to the device using the Blood Glucose
| Profile (https://www.bluetooth.com/specifications/specs/glucose-
| profi...) not an option?
|
| Another approach could be to hack one of those cheap fitness
| trackers (https://rbaron.net/blog/2018/05/27/Hacking-a-cheap-
| fitness-t...). I got a few off AliExpress a few years ago for $9
| each.
|
| Again, not to take away anything from the amazing accomplishment
| to build a device from scratch, but if anyone else wants to try
| making one, maybe they could start with less of a steep learning
| curve.
| andrewchilds wrote:
| I didn't even know about the BLE Glucose Profile - thank you!
|
| Valid question about the PineTime! I'd agree that it is an
| option, although with the dev kit out of stock, flashing a
| custom firmware would be tricky. I think that's probably what
| happened, I looked at this page back when I was first starting
| out on this and was scared off:
| https://pine64.org/documentation/PineTime/Further_informatio...
| noname120 wrote:
| It's quite easy to flash a custom firmware actually and I
| wish I never bought a "devkit" because it's useless (you
| really really need to mess things up badly to need to open
| the watch to flash it directly). You could even have simply
| programmed your app in Python using WASP-OS!
|
| Really an amazing project no matter what! I learned a lot
| reading your article and I don't think that using a PineTime
| as a base would have been nearly as cool
| andrewchilds wrote:
| Thank you! By flashing I really meant flashing +
| programming/debugging so I can see serial output. Can you
| do that OTA? Either way, I'll have to take a closer look.
| raminf wrote:
| I didn't mean to send you down a rabbit-hole since you've
| already built an awesome-looking platform. Just googling,
| came across a devkit:
| https://ameridroid.com/products/pinetime-smart-
| watch?variant...
|
| The DevKit is mainly there to allow easy access the SWD pins.
| It can be flashed via a Pi:
| https://wiki.pine64.org/wiki/PineTime_Devkit_Wiring
|
| Aaron Christophel (go-to guy for hacking wearables) has a
| video on flashing them via an ESP32:
| https://www.youtube.com/watch?v=Iu6RoXRZxOk
|
| For OTA flash, some folks have had good luck with
| https://gadgetbridge.org
|
| For those interested in going the cheap-o activity tracker
| route, here's another old thread on Hackaday, featuring
| Aaron. More good info in the comments:
| https://hackaday.com/2019/02/20/custom-firmware-for-cheap-
| fi...
|
| Also, one last tidbit: I know the idea was to stay away from
| the more expensive devices, but many Apple and Android
| watches have built-in BLE central capability so they can scan
| and connect to peripherals without having to go through the
| phone. In later models, they can even scan in the background
| and update complications.
|
| Again, not remotely as cool as building one's own device!
| numpad0 wrote:
| You nailed Apple corners! That alone shows serious dedication.
|
| couple random nitpicks: - is the motor driver necessary? for
| simple vibrations, just a single Nch MOSFET between motor
| negative to ground(low-side switch) should suffice. - there are
| BLDC vibration motors, because you can(or to eliminate brush
| sparks) - that button cap doesn't look resistant against external
| water pressure, if that's a huge issue, but paradoxically
| waterproof without a drain hole = water container so I can't be
| sure anyway - color paints flake off. simple acrylic clear, or
| super ideally two-part urethane, top coat hides it well. I think
| it's just making flaking of clear layer impossible to notice but
| it works a lot better than color only. - I think I've seen people
| mentioning atrocious power saving of ESP32's entire Bluetooth
| sub-system. it has none or something. - entire watch being sealed
| from top is right choice, as it allows guts to simply pop out in
| an unlikely event of battery failure
|
| but all aside that watch looks gorgeous.
| HumblyTossed wrote:
| > Apple makes it very difficult to do what you want to do, when
| you want to do it, in the name of preserving battery life and
| keeping the device and its other processes running smoothly.
|
| Oh, Apple. You can't just not be annoying can you?
| HumblyTossed wrote:
| > ... I didn't have an OCA laminator, but you know what I did
| have? A cast-iron tortilla press.
|
| HAHA, I love this.
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