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Building a T1D smartwatch for my son from scratch

andrewchilds.com

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Re: Building a T1D smartwatch for my son from scratch

#71

Post by raminf »

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.

Re: Building a T1D smartwatch for my son from scratch

#73

Post by andrewchilds »

raminf wrote: post #71

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…

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...

Re: Building a T1D smartwatch for my son from scratch

#74

Post by numpad0 »

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.

Re: Building a T1D smartwatch for my son from scratch

#75

Post by adrianlv512 »

pipe01 wrote: post #70
andrewchilds wrote: post #54

Earlier quoted context omitted.

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 value…

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

Here's a nice video featuring the product: https://www.youtube.com/watch?v=GqmnV_T4yAU

Re: Building a T1D smartwatch for my son from scratch

#76

Post by adrianlv512 »

andrewchilds wrote: post #54
bbayer wrote: post #38

Earlier quoted context omitted.

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

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 value…

Here's a nice write-up where power consumption is measured using a voltmeter: https://peppe8o.com/raspberry-pi-pico-w-power-consumption/

Re: Building a T1D smartwatch for my son from scratch

#77

Post by noname120 »

andrewchilds wrote: post #73
raminf wrote: post #71

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…

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...

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

Re: Building a T1D smartwatch for my son from scratch

#78

Post by andrewchilds »

noname120 wrote: post #77
andrewchilds wrote: post #73

Earlier quoted context omitted.

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...

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 b…

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.
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