> 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!
Building a T1D smartwatch for my son from scratch
61–70 of 88 posts
Re: Building a T1D smartwatch for my son from scratch
#62I'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.
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.
So AIUI rephrased differently it allows finer grained management before the all hands on deck full tilt red alert alarms go blaring?
Re: Building a T1D smartwatch for my son from scratch
#63Did you ever look into an e-ink display?
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.
Ah - unfortunate. I'm a type 1 diabetic myself, maybe someday I'll get round to doing something like this. Looks pretty fun
Re: Building a T1D smartwatch for my son from scratch
#64Earlier quoted context omitted.
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.
So AIUI rephrased differently it allows finer grained management before the all hands on deck full tilt red alert alarms go blaring?
Exactly right!
Re: Building a T1D smartwatch for my son from scratch
#65Earlier 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…
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.
Re: Building a T1D smartwatch for my son from scratch
#66Wonderful. I'm interested in learning about circuit and PCB design. What would you recommend as the best introductory resources to get started?
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.
Re: Building a T1D smartwatch for my son from scratch
#67I'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.
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!
Re: Building a T1D smartwatch for my son from scratch
#68> 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…
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 t…
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.
Re: Building a T1D smartwatch for my son from scratch
#69And to think, you could have done this in software if you had the right to push your own firmware to your Apple Watch.
Re: Building a T1D smartwatch for my son from scratch
#70Earlier 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…
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