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Low-cost Smartwatch powered by ESP32 module (linuxgizmos.com)
244 points by ofrzeta on Aug 8, 2023 | hide | past | favorite | 80 comments



I have this watch, and got it to tinker with since it had some fun sensors, mic, and speaker.

Haven't turned it on in a while, but the battery life was definitely measured in minutes. It will not last anywhere close to a full day, even with a bunch of optimizations and certain things turned off. Even with the display off, ESP32s drain tiny batteries.

It's only practical for tinkering, and an M5Stack is definitely a better choice for that.

EDIT: Checked my notes. I was able to get it past the 24 hour mark with some work.

This repo has some helpful info: https://github.com/Xinyuan-LilyGO/TTGO_TWatch_Library/blob/m...


Thanks, I almost bought it since it is only $40USD. Yet another sad case of you get what you pay for.

You saved me from disappointment!


I too was interested in that watch. The software looks a bit fancier than my PineTime. It turns out that the PineTime is actually amazing based on battery life alone. It currently costs ~US$27. It's slightly less chunky (37.5mm x 40mm x 11mm) and a bit better looking. Has BLE, heartrate, 3-axis tilt sensor and haptics but no speaker. Battery life has been consistently 8 days between recharges for the last year or so.

Software is okay although I occasionally get annoyed by Bluetooth connectivity issues using Gadgetbridge. But part of the reason I bought it is that it's hackable, so the software is totally replaceable.

I think sometimes you get more than what you pay for. And sometimes you're paying for shareholder dividends and outrageous CEO salaries.


I had no idea Pine64 had a smartwatch (and earbuds?!)

I have a Fitbit Versa that's really starting to show its age, I might have to check the PineTime out. I also have a Bangle.js which was a fun Kickstarter buy, but it's a little too chunky (I see they now have a v2 of it now which looks slicker)


I have the Bangle.js V2 and can confirm, it is a slimmer and slicker overall design, feeling more like a Fitbit Versa. Honestly, it's been a boredom breaker since it's relatively easy to dump new code on to it. My only complaint is the vibrating motor is almost too weak for me to feel when sleep, and as such, is not a reliable silent alarm, so I swap back to my OG Pebble at night.


Their blog is a hilarious adventure through all the Pine* items they've released, their eInk venture and the earbuds are particularly interesting to me...


I also forgot to mention that it's quite ugly and looks very cheap. I personally wouldn't wear it even if it did have good battery life.

Got a galaxy 5 watch a few months ago, which was a much better purchase.


I picked up a galaxy watch 4 on a whim and I gotta say wearos is a trainwreck. Half the value is getting notifications to your wrist but you have to have corresponding linked apps on both the watch and phone. And typing on a watch is a nightmare -- you're paired to my phone! Why aren't I using that keyboard!?

Honestly the Pebble was not that high of a bar. Keep the screen on and send me my notifications and I'm happy.


Pebble was peak smarthwatch experience for me. Simple, straightforward, e-ink display. Super bummed that Fitbit bought them out. My Fitbit Versa is _almost_ as good as the Pebble but it's still trying too hard.


> Half the value is getting notifications to your wrist but you have to have corresponding linked apps on both the watch and phone

At least with my experience with Wear OS 3.5 and 4, this isn't the case. You can get notifications from any app and don't need two apps to do so.


I must be doing something wrong then. I wasn't getting any useful notifications on my watch until I installed all the corresponding watch apps to the phone apps. The watch runs WearOS 3.5. But either way: getting a decent experience should not be this hard.

I've got it the way I like it now but it was a lot of installing software and playing with settings. Which is fun! But it means I would never recommend WearOS to somebody who isn't geeky about Android.


How's that one been re battery life?


Somewhere around 2 full days. I usually stick it on the charger when I sit down at my desk, and less than 30 minutes is plenty to get it back to 100%. 0 to 100 might take around an hour.


You can get a Mi Band for about that price, and it's a good smartwatch with great battery life (admittedly the software isn't the best).


What issues with the software have you had? I’ve got one and really haven’t had any problems using it in combination with my iPhone.


Occasionally it won't sync a workout when I ask it to. There was a confusion of which app to use and which accounts you need to sign up for (Zepp versus whatever the other thing), and it seemed to ask for a bunch of info. Up until the 7 you couldn't turn it off. Mostly it just feels clunky. It does the job but it's not what I'd call delightful to use.


Esp32 isn't a very low power device. You'll never build anything with a battery life measured in months off a coin cell with it.


Lol not true, you even have a low-power core (https://docs.espressif.com/projects/esp-idf/en/latest/esp32/...) in each esp which lasts on a coin battery for years.

Sure it won't last long if you use pause and you are connected to wifi. You have boards with a power management chip that allows you to do even more smarter things, for example https://www.hackster.io/news/smart-bee-designs-bee-s3-is-a-1...


The ULP coprocessor only claims a power consumption of 150 uA (which is huge compared to actual low power devices - EFM32, which is an ARM Cortex M3 MCU, runs on just 1.45 uA)

Combine that with the fact users see real power consumption up at 450 uA [1], you won't be writing a program that lasts more than about 3 weeks on a regular CR2032 coin cell.

[1]: https://github.com/espressif/esp-idf/issues/7882


That's a 2 year old github bug being fixed, not the actual usage people obtain in the wild.

Here's [1] a commercial ESP32 board that draws 1.5uA, and, as others point out, comes with vastly more hardware at a lower cost [2] than the EFM32 arm core you listed.

[1] https://www.tindie.com/products/kdcircuits/trigboard-ultra-l...

[2] $1.10 for ESP32-C3 on digikey, vs $1.34 for EFM32PG22C200F64IM32-CR. The ESP-32 is better for pretty much every spec possible.


This was then resolved (id depends on the use case also), also you are comparing Low Power CPU (ARM Cortex m0-m3), which you need to pair with something probably esp32 to connect it to the internet.


Yeah, por ir on deep sleep and wake it up briefly once a day and try not to use wifi


Shameless plug of my failed project: https://paulrouget.com/k8mod

The idea was to literally fit a Nordic SoC in a Casio watch, and update the screen to show more segments.

I never managed to find someone to manufacture the screen sadly.


I love this! As a daily user of the F-91W I do on occasion wish it had a few more features, but it mostly satisfies my needs. I love the form factor and the weight. I just wish it at least had a countdown timer.


You wanted to build a screen? Is there no screen with that size?

Maybe not lcd, but eink instead


This type of LCD are custom made because of the particular segment layout. See the /screen/ section in the linked page.


But you could just have an eink display with higher resolution and build segments out of pixels. Maybe it doesn't look as good but would be more flexible and would have a chance of actually shipping a complete watch


Loved the idea. Fascinating blend of design and functionality. You should kickstarter this.


agreed, the only way i got enough capital to fund a batch of injection molded cases was by kickstarting

my secret was not trying to turn a single kickstarter into an entire business ;)

more of a 'drop' mentality really helps

also: https://news.ycombinator.com/item?id=37054130


Beautiful write up and project!

I remember reading about another Casio retrofit:

https://github.com/carrotIndustries/pluto

That version did not have wireless comms - they touch on that in the faq.


Yeah, the sensor watch [0] also mentioned in another comment re-uses the original screen.

[0] https://www.sensorwatch.net/


Shit, this is just what I want. A casio with vibration notification. If you ever get back in, I'll definitely buy a couple just to support you.


As a daily user of this watch that's exactly the kind of smartwatch I would love to buy.


oh my goodness. That is beautiful - an amazing design for a first hardware project and I would love to see it come to fruition. No experience from my end that would assist, but all the best.


What's so failed about it


I've never managed to build the screen. A smartwatch without a screen is not great :)


I've a bangle js. I find it the perfect watch for hacking. It's similar to the pebble watch. https://www.espruino.com/Bangle.js2

Apps are written for it using espruino javascript. I get over a week battery life of of it.

https://banglejs.com/apps


Seconding the bangle. Great battery life, good ecosystem, very hackable. Not a replacement for an Apple Watch or people, but very capable.


I might have to pick up a Bangle.js2. I have a v1 but it's too big for me.


Very cool that this one has Lora!

Another fun low-cost smartwatch with fully customizable ROM is https://pine64.com/product/pinetime-smartwatch-sealed/ . Wearing one right now. Not as powerful a processor though, and only BLE for connectivity, but battery lasts days.


I forgot what LoRa means, so I googled it and got this amazing tutorial:

https://randomnerdtutorials.com/esp32-lora-rfm95-transceiver...

Seems like it helps even complete beginners to learn and build something interesting. Other tutorials there seem just as good.




+1 for the SensorWatch. I've been using it for a few months now and it's been flawless. I prioritize battery life above all else, and only recently has the battery been dropping in voltage. Opening up the watch to do any SW changes is a bit of a pain, so if you constantly want to make changes it could get annoying.


Although I've been a working EE for 40 years and understand how exponential growth works, I'm still shocked at how powerful it is and how little it costs.


And at $40, this is relatively expensive for the amount of power. You can find a ESP32 dev board on AliExpress for about $5, shipping included. It is obviously much cheaper if you buy the chips in bulk.

Here, you are mostly paying for the smartwatch package, not the brain.


the best bang for buck board right now is the esp32-s2 based s2 mini. Its great for doing anything usb attached (keyboard, gamepads, mice, anything really). Its about 2,50EUR at its cheapest including shipping without PSRAM and 2,60 with psram.


I wonder if the display could be changed to https://www.waveshare.com/product/rp2040-lcd-1.28.htm


I have played with this device and got CircuitPython working on it. It’s fairly undocumented but with the demo apps source I could get the touch, accel, and screen working. However I’ve not been able to get the battery to last more than an hour even with screen blanking.


I saw that waveshare link and was really hoping for some eInk stuff. I would buy a package like that in a heartbeat if it had eInk. Heck, might even get a couple if the price was right.


Exactly what you're looking for https://watchy.sqfmi.com/


Wow very neat, thanks! Happen to have any other similar suggestions? That one is backordered for months.


Wow this is pretty neat and surprisingly affordable. Looks like it'd be great for making digital gauges for a car.


Funny to see this here as I stumbled upon this company earlier today. They seem to have a wide range of interesting products and an active GitHub account.

https://www.lilygo.cc/collections/all

https://github.com/Xinyuan-LilyGO/


This mostly just reminds me that I really miss my Pebble Time Round watch. Perfect form factor, great battery life.


I had original Pebble and even 7 day battery life was a bit annoying, couldn't imagine having to charge my watch every 2-3 days as some modern smartwatches have. Ended up getting just a solar powered casio with no smart features whatsoever...

Garmin makes ones with over 2 weeks of battery life but for the money I can't excuse spending on a watch just to get some gadgets.


2-3 days? I charge my watch every day, or I risk it dying in the middle of the second day.


I had a earlier Pebble, which was neat, but it mostly just got used for cycling so I could see who was calling without pulling my phone out. It was an interesting proof of concept for the time.

When it died, I tried a couple of things for my "active watch" before settling on a first-gen Apple Watch. It turned out to be so dang USEFUL that I wore it more than I wore my real watches, a trend that continues to this day.


Makes me wonder how we all lived before Smartwatches. Were train commutes really that boring before the smartphone came about?

Every day I walk to work listening to music on my minidisc player. Looking around to all walking zombies staring down at their phones; as if the news, social media or whatever is a great thing to absorb first thing in the morning.

Technology has engulfed us.


> Every day I walk to work listening to music on my minidisc player. Looking around to all walking zombies staring down at their phones;

There were many people that made similar statements about people listening to their walkman/mini-disc/etc. "People these days can't be bothered to listen to the goin' ons around them!"

Things change over time. Today's phone focused masses will be complaining about the cybernetically enhanced AR users of the future, or whatever crazy technology comes out.


Yes, I've heard ppl make this response all the time that "its just like what people said in the past". It makes sense but I really think that "smart devices" in particular are different and a lot worse.


>Every day I walk to work listening to music on my minidisc player. Looking around to all walking zombies staring down at their phones; as if the news, social media or whatever is a great thing to absorb first thing in the morning.

I don't get how that's a much different disconnect than the person on their smartphone, it's just one that you're comfortable with differentiating yourself using.

there was a point in nearly every transit-style life-span where the entertainment was supposed to be the thing itself. It would have been seen as despicable to read a novel on a very early passenger air flight -- the thrill and entertainment is supposed to be the thing itself.

Then it gets normal, then it progresses to boring, and then you tune out.

It seems like a pretty normal progression, and it has happened time and time again; it'll probably happen with again with flying cars/human-cannons/transporter beams/whatever, too.

p.s. I loved the MD format, is it still practical at all to use? I can understand using it for the powerful seeking ability and such that has gone to the wayside nowadays but aside from that it seems less convenient than a small cheap mp3 player of some sort.. if I still had that equipment i'd probably still be playing with it too, though; md insertion is so satisfying from a mechanical point of view.


> Were train commutes really that boring before the smartphone came about?

Yes. You had to buy a physical newspaper/magazine, which was simultaneously more expensive and less interesting.


There's always something that people are doing that is considered "engulfing" in a negative sense. I'm sure if you saw somebody reading a physical book, you'd think "how quaint!" but even that was seen as an unnecessary distraction if you go far enough back in time https://archive.nytimes.com/op-talk.blogs.nytimes.com/2014/0...


> Makes me wonder how we all lived before Smartwatches.

I remember they had books, back then. And you could look out the window (:

Actually, I don't have a smartwatch and don't want one. I guess I'm at a phase in my life where I'm looking for less attention-grabbers, not more.

I've always found a blank piece of paper and a pen were a good way to fill an hour, too.


> Every day I walk to work listening to music on my minidisc player. Looking around to all walking zombies staring down at their phones

When the Walkman came out, it was seen as incredibly antisocial to listen to your own music while out and about instead of participating in the world.


You say that, yet I can ask these people something. Not so much with those who wear headphones, I have to gesticulate to catch their attention, or (gasp) touch them :)

It's an all-in-one device, so everybody uses it to do something different. Some listen to music, others play games, most seem to stick to scrolling Instagram/tiktok/whatever. I personally reqd my RSS and help people out on IRC during long rides. When commuting regularly, I tend to take a book with me, as that requires a longer commitment.


First you're talking life before smartwatches, then MD players. I wish I knew what happened to my MD player, I was only 8 or 9 when I was given it. And burning MD seemed as insurmountable a problem as affording a zip 100 drive at the time. Point is, before we had smartwatches, WE HAD MINIDISK PLAYERS.


I can see it uses 3.7V/400mAh battery, but whats the actual battery life?


AliExpress reviews seem to say 12h or so with all the power saving features turned on.

Without the power-saving... An ESP32 draws 90-240ma when active, and I'm sure the battery capacity is significantly overstated, so if you just flash a simple Arduino sketch it'll probably drain the battery in under an hour.


That seems like an excessive amount of power. Does the running program/OS just have zero power saving consideration given?


That would be while the radio is active. I would expect 30-50mA with the radio off, 1-3mA with automatic light sleep enabled (the CPUs will automatically enter and exit light sleep as required, even with WiFi connected), and 5uA in deep sleep.

Cheap boards like this may use external components (eg. voltage regulator, LoRA) that add tens of milliamps in quiescent currents, but a well-designed ESP32 device can achieve impressively low power.


I managed to make esp32 stream video for 6h using two 18650 batteries. It is hungry.


What’s the low power alternative?


No idea, I use esp32 because of price.


I know a guy who was trying to make low power sensor networks of what I assumed were esp32s. It’s news to me they are power hogs. I’ll have to ask him but I won’t see him for a couple of weeks. Stm32 maybe?


Nice project idea. The Nordic chip in the Pinetime might be more efficient than this ESP-32 though, and there's been a lot of development effort into infinitive for it.


And the battery lasts for how many minutes?


Yeah, the esp32 is so power hungry that despite of its wifi, it is not at all mobile


Nice job.




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