PebbleOS isn't the only player in this space. There's also https://www.espruino.com/ which powers https://banglejs.com/. It's a tiny implementation of Javascript for microcontrollers, so it's really easy to hack your device in real time.
Had never heard of bangle js, love the idea of fiddling with it with a languange I already know.
Would love to buy the 1st version, as I don't like square designs, but it seems they don't sell it anymore.
I’m confused, is bangle js manufacturing new hardware (and is that open with schematics, bom, gerbers) or just shucking an existing cheap Chinese smart watch (SMA Q3)?
Zephyr provides an open source implementation of all layers of the BLE stack. The radios of some devices are documented extensively, Nordic nRF5 devices are probably the best example.
The Bluetooth SIG requires that you qualify your device if you advertise that you use Bluetooth IP, similar to what is required for the cellular space. Do you have to do this if you’re just “Bluetooth compatible?” Maybe not. Whatever the case you have to conduct FCC part 15C testing (intentional radiator).
I have yet to see a real case of "binary blob for regulatory reasons". What law prevents open source RF firmware?
The device needs to operate in spec and if someone reflashes it with out of spec firmware, that's no different than someone soldering a different resistor onto the PCB or feeding the output of the chip into an amplifier and large antenna. It's a modification by the user and so the user is liable for operating out of spec. And all of this really unrelated to source code, just to reflashablitiy. The code could easily be open, but the productions device could be made unflashable if the law really required it. Yet this is not what we see here.
It's IP reasons, and that's fine, but let's not make up additional excuses for them.
> The code could easily be open, but the productions device could be made unflashable if the law really required it.
Excellent point. Many people (myself included) do assume that open source = redeployable, as in GPL3. I guess an e-fuse for read-only is perfectly OK, both from regulatory standpoint, and for ensuring you're running the same code as what you have the source for. That would be cool.
I know very little about bluetooth firmware beyond using it for apps and such, but what kind of regulatory reasons are there that prevent publishing source code for bluetooth radios?
The BT blob (or WiFi blob, or general radio blob) often controls low level aspects of the actual RF device. So you can often alter frequencies, power levels and other parameters. This results in the device acting out of spec.
Now one might say that's the fault of the person doing the modifications/manipulations, but regulations in various countries require the device to prevent these manipulations.
(N.B. I'm not in the exact business, but that's my take away from looking into the topic some time ago)
That was my takeaway as well when I was working with Bluetooth modules a few years back.
There were a few more reasons too, at least at the time. The companies in the space didn't have a culture of open sourcing, and there's probably no perceived commercial upside to releasing code for a chip like that.
I think often it's also a combination of what you described and big companies being super risk-averse. Why risk breaking regulations if you can just say no?
Then again, lots of Wi-Fi-enabled devices support simply changing their region setting and will happily let you use different Wi-Fi bands or increase signal power.
True but those bands are still official wifi bands somewhere.
On software-defined radios you can often use them way out of spec, way more so than using a forbidden channel. But in a totally different band. A good example is the RTL-SDR stick which was designed to be a TV received but can be used as a wideband SDR these days. That's a receive-only device so it's not that critical to regulators. Once you can transmit, it becomes more of a problem.
An example of a more problematic transmission device is the Raspberry Pi PWM pin. That's been used to transmit all sorts of stuff on many bands. Because it was never designed to transmit anything, it causes all kinds of weird harmonics and artifacts. It's a really bad idea to use it for that. Most people just do it under controlled circumstances.
The hardware itself is flexible and relies on software for things like calibration, setting frequencies, and setting power.
> Seems like security by obscurity.
There are legal standards to meet around protecting the system from users modifying things like output power. They don’t literally say that the source code must be private, of course, but keeping it closed source makes it much easier to demonstrate that you were not making it easy for people to exceed the regulatory limits.
If you document the registers for setting output power (for example) then you’re giving the end user a roadmap for changing output power.
I don't know, I don't think there are many open-source third-party firmware implementations for these kinds of chipsets out there, so it seems pretty well obscured.
Exactly my thoughts. To avoid out-of-regulation tweaking coudn't they just allow signed code to run? How can I be sure that this closed for, i.e. surveillance reasons?
One can publish the source code and still prevent misuse afaik.
Many modern chips do in fact use signed firmware yes.
Technically they could publish the source in that case but I think some patents would prevent them from doing this. Radio stuff is riddled with patents. Also most likely the "why would we" reason. There is no benefit for the manufacturer.
Why would patents prevent open source? As in, they're afraid of patent trolls trawling their code for "infringements"?
If it's concerning their own patents, no need to hide the source code. A patent is literally "letters patent" or public description of an invention. Trade secrets on the other hand I could understand.
It's often a condition of licensing those patents. NDA's, they're huge in the radio and embedded world. It only became a bit more open when the Arduino and Raspberry projects came along. And even there it wasn't fully open, especially with the Raspberry because Broadcom is one of the worst offenders.
I'm surprised how much they were able to open source as-is. I think part of that is that the SoCs powering the raspberry are kinda 'old news', definitely not the bleeding edge kind of embedded tech. The first raspberry basically happened because Broadcom had a whole bunch of old chips they weren't able to sell. Only when it took off they started making some actually for the purpose.
This smartwatch isn't really all that smart by today's standards.
I would really miss the mod cons I have on my current smartwatch. Payments over NFC, dual-band GPS tracking, 4G LTE connectivity. The Pebble (and repebble) trades all that in for a multi-week battery life. But the minor hassle of once-every-two-days charging on my galaxy watch really isn't enough to forego all these powerful features for me.
Conversely, I don't care about any of those features, and I do care about long battery life. It's great that different devices catering to different users exist. I don't think the fact that they are aiming at different users from you makes it "not smart", it just makes it not suitable for your use.
Same, I love Pebble and Pebble-like devices precisely because they have long battery life. I don't want or need payments on my watch. I'm also not a fitness junkie, so I don't use GPS tracking either. I mainly enjoy the well-designed UX Pebble provides and its simple functionality like alarms, stopwatch, and notifications.
With watches that need charging every one or two days, I get this Sisyphean feeling that I am owning a constantly dying device with a battery indicator that exists solely to be charged. The amount of functionality a watch can provide me (versus a smartphone) just doesn't justify the amount of charging I need to do.
Maybe I'm not a smartwatch power user like OP. But the Pebble and its ilk are a great fit for the niche audience I belong to.
There are other full featured smart watches like the Garmin Enduro 3 with several weeks of battery life (or even longer with solar charging). Of course it's larger and more expensive.
No one really needs payments on their watch but I'm surprised that anyone wouldn't want it. It's quite convenient, and gives you a backup option in case you forget your wallet or something.
Don't get me wrong, I backed the first Pebble on kickstarter. Still have it. It was a great watch for the time. I loved it.
But these days I just have bigger requirements. The whole heartrate thing I don't even care about. Notifications are the main thing, but route tracking, integration with my alarm system and above all payments are just things I can't do without anymore. I had an Amazfit for a while which also had a 3-week battery life (though no apps) but it missed the payment option.
The charging is not a big deal for me because I only wear my watch outside anyway. And it charges in 30 minutes. It makes it easy for me to keep it charged also because it becomes a routine. With the amazfit it was often empty when I needed it.
But yeah it is great that there are devices for everyone.
Maybe you mean types of notifications that I'm not used to using, because notifications were the first thing I would turn off on any smart watch I've used (pebble, Amazfit, galaxy). The last thing I need if to have yet another device (now being worn) vibrating every 5min for some message.
Truth be told I use the least smart feature of the watch: the alarm. I can set quite granular schedules for my alarms and that means no one else needs to wake up but me. The health tracking I barely care, but since I'm wearing it I track it. I could imagine using the payment feature tho, to avoid taking the phone out.
> Maybe you mean types of notifications that I'm not used to using, because notifications were the first thing I would turn off on any smart watch I've used (pebble, Amazfit, galaxy). The last thing I need if to have yet another device (now being worn) vibrating every 5min for some message.
At least on my smartwatch (Samsung one) I can choose which notifications I want to forward to the watch. And I have all the ones I don't care about turned off anyway, even on my phone. For me it replaces a lot of my smartphone (which I only use outdoors anyway, at home I have a real computer). The ability of the galaxy watch to also show pictures in notifications is a big plus (my old pebbles could not do that, not sure about the new repebbles)
The notifications on my watch are the main reason I have it. It avoids looking at my phone every time something comes in. It's not too often because I block so much and I don't use social media.
I don't care much about the health tracking, though I do sometimes use the sleep tracking. Especially the SpO2 tracking is handy because I have apnea. It does bother me that Samsung doesn't make it possible to turn off their health "gamifications" (every day I get nonsense messages like "Will you meet your goal today?", "You're halfway your goal, keep going!"). I still have to see if I can turn that crap off via ADB.
I'd add that it also ignores that Garmin already has multi-week battery life with most of these features and more. The only thing they don't have is 4G yet, but I believe next year's devices have been reported to have it.
I too would miss GPS, BUT I've still never found anything that really fills the pebble shaped hole in my life. My Garmin compromises the other stuff (battery, widgets, calendar, display readability etc.).
It is for me, I don't care about any of those features. I just want a watch I can customize a bit that gets notifications and can do rudimentary heart rate monitoring. If I have to charge it more than once a week I won't wear it.
Interesting they did not go with 2-chip design(1 for main application, 1 for BLE stuff). Which is sometime makes sense because high power mcu usually does not have RF
The "high-end" modern MCUs are pretty great, you have the NRF offerings, but also the likes of the ESP32 where you can get Bluetooth and WiFi in a single package.
Personally these days I would lean towards the ESP32, they continue to iterate on it nicely and it has great community support. I'm personally developing a smart watch platform based on micropython.
While the ESP32 is great for many applications, it’s not for battery operated stuff. When an nRF draws 1-2 mA when using BLE, ESP32 will draw 40 mA. And the chip they selected is even more efficient.
The low power chips can also run in low power mode without BLE running using micro amps, something the ESP can’t match.
I really like ESP32 and I hope they have a low power chip on their roadmap.
Sure I agree, but the WiFi functionality is a killer feature. As mentioned in another comment, it means a smart watch stops being a smart phone addition and can actually operate as a stand-alone device.
Years ago I had a "smart" watch that had a sim card and was a full mobile phone within its own right, I think it was just 10 years or so too early.
Manufacturer lock-in can be quite a problem. I'm not saying the ESP32 solves this fully, but you can mix and match as you like, and it's highly encouraged. I think with the ESP32 most build upon Free RTOS but I'm not aware of a strict requirement.
Of note, you can just pull in a lib to use Wi-Fi and BLE on an ESP32 (C-3 at least). I've done it. It doesn't imply any changes to your firmware architecture. That's the part that bothers me about Nordic's approach.
Not insanely for a smart watch. Your smart watch battery will be something like 200mAh, so for 20 hours you need to average 10mAh. With zero optimisation, screen refresh rate at 30+fps, I have smart watch chewing 30mAh.
Getting down to 10mAh is not so bad. If you're not actively driving the display, you can under-clock significantly [1], if you're not using WiFi you can turn the modem off [2].
It might be just-about acceptable for a smartwatch. But anything the micro takes out of the power budget means less screen and radio time, which does add constraints.
PineTime, based on NRF52, will get you 4-7 days of practical usage.
There are ESP32 watches. One I have[1] comes with quite thick 940mAh battery but my understanding is the battery life still isn't that amazing (just got it, haven't really tested the battery) - something like less than a day of constant runtime or few days if you turn it off constantly
Yeah I got one of those as well. An the older non-S3 version. Fun for developing, very powerful. I use it for developing ML applications for watches etc (emlearn project). Great device for that, but battery life is not its strong point.
Can confirm, I regularly get about 9 days of charge on my PineTime, running the latest PineTimeOS release. Its gotten better and better over the years, and the functionality keeps coming ..
I used to use the PineTime with PineTimeOS, but mine eventually broke (corroded inside), but not having WiFi made it annoying to develop for. With WiFi suddenly you don't need to communicate regularly with a phone and the possibilities really open up.
I'm getting 10 hours run time with the screen continuously running and drawing graphics every refresh in micropython - extending this time out is definitely possible.
There are many ESP32 variants, depending on what you pick some may be more compelling for your use-case.
I think once we start talking about GPU, MMU, USB, display, etc, we're getting towards a CPU of sorts.
Speaking of a low-end CPU, I want to test out the RV1103 Rockchip, those crazy little chips are running Linux apparently [1], and even able to run Python [2]. Depending on power draw, a Linux-based smart watch could be on the horizon.
You got downvotes but im a firmware eng and can point out more esp deficiencies. #1 completely fake FPU that they lie aboutm. #2 awful memory bandwidth. Not only slow but unpredictable. #3 small onboard memory. #4 low clock speed.
The Cortex-M33 core in the SiFli chip will be much faster than the M4 cores that the fastest released Pebble watches used, so a faster MCU than this is not something that's needed. However, more battery life is very welcome, and the fact that they're using MCUs with integrated Bluetooth this time seems to be a huge part of the upgrade from about a week of battery life to about a month of battery life.
Interesting comment, because according to https://en.wikipedia.org/wiki/PDP-7 the PDP7 (the first computer "UNIX" ran on) had ~9.2KB of memory (supporting up to 144KB).
Most contemporary SoCs will have more memory (and compute power) than that.
the more chips you have, the more complex the project becomes. BOM is one thing, every chip needs support passives and oscillators, but now you also need to coordinate communication between the chips, you need to devise a way to update firmwares and access both chips for debugging purposes... that might be worth to trade off for less battery life.
in my experience they are not that much difference between 2 design. The BLE FW is a binary blob that you will download at boot with 2 chip-design, or load it to correct address with single chip-design.
> in my experience they are not that much difference between 2 design.
Depends!
If the two chips use UART or SPI for intercommunication, okay, you need two lines between the CPU and two GPIO lines for wakeup, and JTAG can be shared anyway.
But if you use stuff like shared memory, or want to do stuff like updating the display not just from the high-power chip but also from the low-power one, suddenly design becomes much more complex.
Glad to finaly see someone in the low-power chip industry going in the open source direction. Thanks for the insight!
When I saw rePebble be announced, I signed up for it right away. Only later I realized I actually don't want a smartwatch, I want a dumb watch with vibration notifications.
I know I'm in the minority, but it's a niche that has a few very interested people in it [0] [1] [2]
After wearing the Casio F105 for the past 2 years, I can't go back to something larger, heavier or thicker than this. I could accept weekly battery charging for the benefit of having some bluetooth functionality.
So nowadays I'm looking for a super small bluetooth chip that can power a small vibration motor, which can receive all notifications from my iPhone. I would like to glue that chip, motor and a small lithium battery between the two straps of my F105, because in my tests it seems I don't notice if I add a small weight there.
I still remember when I first used my first Mi Band 1, a forgotten fitness band that had no display, just 3 RGB LEDs that could even get specific colors based on the app that sent the notification. I could know right away when I got a blue Messenger chat that I needed to answer now, or a yellow Google Keep reminder that I could ignore until I got back to my computer.
This might be out of scope, but citizen makes the W770, I recently bought one for <200US lightly used. It manages to be a pretty good chronograph , BLE with an alarm and vibration motor (with a somewhat neglected strange little ecosystem of scriptable notifications).
As a watch, it does require that you read the manual completely to understand its various interface paradigms, but it’s reasonable given that there is no display per se, only hands, to show all of the information. Also, you may need to synchronize the hands at first setup, that baffled me at first lol.
It’s efficiently solar powered using a super capacitor, with months of battery life if left in the dark, no battery concerns at all if you wear it (unless maybe you are an actual vampire that also cannot tolerate artificial light)
The supercapacitor can be replaced if it wears out, seems to be reliable for about 15-20 years based on their other watches.
I like mine quite a lot, it’s a well built actual timepiece, put it on and forget about it if you want. It doesn’t ask you to do anything for it to just do its job, year after year.
Citizen may have other options as well with BLE, idk.
Id love to see someone reverse engineer the notification / BLE communication protocol and create an open source companion app - the possibilities for hacker-y types would be pretty cool.
I still rock my OG Pebble and while I am excited they're coming back, I have no plans to upgrade.
Like you, my needs are simple; vibrating alarm, notifications, but with one key factor; I need a display that I can read in broad daylight that plays nice with my far-sighted eyes. The eInk display on the OG Pebbles hits the mark. Being able to read a text without pulling out my phone is also nice.
Plus they can be got on eBay for about $30 USD and a fresh battery is about $15, so they don't break the bank. The Rebble.io community's work is still functioning well enough for my use, as well.
Small correction, pebbles use a TFT "e-paper" display, not e-ink. This is how they have reasonable refresh rates for animations and no after image problems. It's the best compromise imo
> I want a dumb watch with vibration notifications.
Same. Notifications are rarely time-critical. A few years ago I noticed that I kept getting distracted by my phone alerting to some nonsense which really didn't matter, so I completely disabled all notifications. I'll just look at it once every few hours to respond to incoming messages.
A regular smart watch would be pretty pointless for me. Getting stuff like message notifications on my wrist would be a huge anti-feature. However, it would be pretty nice to have a convenient way to set an alarm, which will vibrate on my wrist when it goes off. I want a "leave now to catch the bus" reminder, or a "it's time to take a break" reminder! That's all, nothing more, no need to add any fancy sensors.
I agree. I’ve been looking for a “smart” watch strap or strap clasp I can use with my vintage seiko watch. I just want vibration alerts when very specific things happen on my phone. My wife is calling etc. Dont need all the features or display of a typical smart watch. Too distracting.
I had a Seiko watch for decades that needed a new battery every 5 years, and I still miss it. It never left my wrist except for battery replacements. The Casio mentioned above goes one better by using solar, so it would never have to leave my wrist - and it has a BLE connection to the phone. But it doesn't have enough sensors, like an accelerometer.
Withings smartwatches come do closest, and that's what I have now. Their standout feature is their 30 day recharge, but they still have a ways to go.
They are expensive, but worse they are fragile and no one will repair them in most countries, and the rechargeable battery means they will only live a few years. On top of that I'd like to see them add NFC, payment card and passkey integration, with better security so if they leave you wrist you have to re-authenticate or reset them. None of these things require much (if any) power. Also while the analogue time is great, interacting with the digital interface is clunky. A single button is not enough. The digital interface could be bigger, and could display more - like displaying the last few message.
So my take is while smartwatches are improving, they still have a ways to go. And that way is not the direction Apple appears to be taking, which seems to be to put a power hungry iPhone with a miniature screen on your wrist. I'm hoping the old watch manufacturers will come back with their robust very low power designs, with a few added sensors.
The Scanwatch Light seems to be very close to what I need. While they're priced reasonably for what they offer, they're crazy expensive for what I would need. I'm really not interested in fitness or sleep tracking these days anymore.
I'm also a bit scared of the many "charging issues" some people seem to have with them after a few months, but I guess every batch has a few bad devices so I could hopefully return it.
Thanks for the recommendation! I might try one soon.
For what it’s worth, after I bought one, around five other people I know got them, varying models from the Steel HR to Nova, and haven’t been made aware of any issues. Of course, personal experience doesn’t apply to the mass of products, and these are all UK SKUs, so who knows if issues vary between countries as well?
Overall everyone has been happy though and I haven’t seen Withings come up on HN which is surprising tbh!
Apparent my wish for a fitness tracker that's not a watch is also pretty niche. I know that there are rings, but I also don't like rings.
Basically I want a bracelet, if it must be on my arm, but ideally it would be an ankle bracelet. I'm not sure that would provide a convenient spot to get heart rate, or data beyond steps.
I justify the ~$20/mo the same way I justify a gym membership: it's a bargain if it's compelling you to make positive choices about health/sleep/exercise. If it's not, then yeah, it's just an expensive mood ring.
Full disclosure, I worked many years at Fitbit, in a very senior role.
The reason you want Whoop to have a subscription (and why I wear a Whoop now) is because it incentivizes the company to ship great hardware _and_ software. If you don’t have a subscription, your company becomes stuck on the treadmill of needing to have a new device to sell to the public every year (or even twice a year) so that you can continue to fund your business. Pebble found this out, too, and it led to their sale eventually.
Worse, the launch dates are not movable. People are largely not going to wait and buy your new watch in January if they wanted to get a Christmas gift for their spouse. The same goes for Mother’s Day. The scope is also not movable, because it has to have certain things for people to be interested vs last year’s model. We all know what happens when you fix scope and date in the iron triangle — quality suffers.
The subscription model has a great property — you can ship the device to your customers when it’s ready and meets your quality bar, and you can theoretically do it for free, because they are already paying a subscription. I realize Whoop did not take this path with their latest device release, they are clearly trying to goose their revenue for a quarter or two. That said, at the end of the day, their full product offering will either earn your subscription or not, which means that you can be confident that they are aligned with your interests. You generally cannot say that about a pure hardware company, unless they are remarkably disciplined with respect to hiring. I have not seen an example of this in the wearable/health space.
I think you can derive a general principle from this, which is that if a company is incented to sell you crap, they will eventually do so. If instead they are required to repeatedly earn your business, they will either maintain high standards for their products or they will go out of business. I mostly choose to spend my money on products made by companies with the latter model.
NB that Whoop did pull a fast one on users. People signed up with the promise they wouldn’t have to pay for hardware upgrades. Whoop recently dropped that right before releasing their first hardware upgrade.
There's two big factors that make software compatibility very important for this product specifically.
1. His team is positively tiny compared to what Pebble used to have, and the less software work that's needed, the better.
2. All of the apps and watchfaces people wrote for the original Pebbles were distributed as compiled ARM binaries, so if you picked an MCU with an entirely different instruction set, you'd lose backwards compatibility. ESP32 would fall into that category, for example (not that it would have been a good choice anyway).
There are solution for question 2. You can either add a compatibility layer to the software stack(something like Java VM), or people can build their app against your codebase, and your watch will dynamically load it and run(like how linux run their app). In Zephyr they have LLEXT for that.
I mean, these applications are by necessity very tiny. They must fit in a very small memory. Hence, I seriously question that it would take a lot of work to rewrite the software for a different architecture. You can reuse the entire graphical design (which is probably a large chunk of the work because designing for small screens is not easy).
PebbleOS isn't the only player in this space. There's also https://www.espruino.com/ which powers https://banglejs.com/. It's a tiny implementation of Javascript for microcontrollers, so it's really easy to hack your device in real time.
It also powers the Fallout Pip boy and possibly some other stuff from the wand company: https://www.thewandcompany.com/fallout-pip-boy/ See: https://github.com/orgs/espruino/discussions/7577
Had never heard of bangle js, love the idea of fiddling with it with a languange I already know. Would love to buy the 1st version, as I don't like square designs, but it seems they don't sell it anymore.
I’m confused, is bangle js manufacturing new hardware (and is that open with schematics, bom, gerbers) or just shucking an existing cheap Chinese smart watch (SMA Q3)?
They sell existing hardware with their firmware. You're right, the bangle.js 2 is a SMA Q3 (https://hackaday.io/project/175577-hackable-nrf52840-smart-w...)
appreciate the shouting out of good work for lower profile competitors. Pebble is awesome but they deserve some love too. thx
also everyone watch the Amazon Fallout show if u have the chance its p good
See also: PineTime.
"The SDK is open source" Oh, a BLE MCU with open source code SDK?
AFAICT, the BLE code is provided as a binary blob. https://github.com/OpenSiFli/SiFli-SDK/tree/6c82a9b15db49871...
Which isn't a problem. But, I wish if something is described as "open source", you could read the source code for it.
BLE radio device firmware is always going to be provided as binary blobs for a combination of IP and regulatory reasons.
Zephyr provides an open source implementation of all layers of the BLE stack. The radios of some devices are documented extensively, Nordic nRF5 devices are probably the best example.
The Bluetooth SIG requires that you qualify your device if you advertise that you use Bluetooth IP, similar to what is required for the cellular space. Do you have to do this if you’re just “Bluetooth compatible?” Maybe not. Whatever the case you have to conduct FCC part 15C testing (intentional radiator).
> you have to conduct FCC part 15C testing (intentional radiator)
Maybe soon you won’t.
Care to elaborate?
Maybe orange man will abolish the FCC because rules are inefficient
He won't abolish the FCC. It is too efficient at attacking his enemies.
looking at his policy to China and Russia, maybe his enemies are not what we thought
His enemies are Americans that don't bow down.
I have yet to see a real case of "binary blob for regulatory reasons". What law prevents open source RF firmware?
The device needs to operate in spec and if someone reflashes it with out of spec firmware, that's no different than someone soldering a different resistor onto the PCB or feeding the output of the chip into an amplifier and large antenna. It's a modification by the user and so the user is liable for operating out of spec. And all of this really unrelated to source code, just to reflashablitiy. The code could easily be open, but the productions device could be made unflashable if the law really required it. Yet this is not what we see here.
It's IP reasons, and that's fine, but let's not make up additional excuses for them.
> The code could easily be open, but the productions device could be made unflashable if the law really required it.
Excellent point. Many people (myself included) do assume that open source = redeployable, as in GPL3. I guess an e-fuse for read-only is perfectly OK, both from regulatory standpoint, and for ensuring you're running the same code as what you have the source for. That would be cool.
I understood the criticism to be about describing it as open source when it isn't, i.e. that
"We say it's open source because we expect the reader to know that we're not telling the truth"
should be replaced by
"It's open source except for the BLE firmware blob, which can't be open source due to regulatory reasons."
To be fair, the article just repeated the claims made on the GitHub page for the SDK.
I know very little about bluetooth firmware beyond using it for apps and such, but what kind of regulatory reasons are there that prevent publishing source code for bluetooth radios?
The BT blob (or WiFi blob, or general radio blob) often controls low level aspects of the actual RF device. So you can often alter frequencies, power levels and other parameters. This results in the device acting out of spec.
Now one might say that's the fault of the person doing the modifications/manipulations, but regulations in various countries require the device to prevent these manipulations.
(N.B. I'm not in the exact business, but that's my take away from looking into the topic some time ago)
That was my takeaway as well when I was working with Bluetooth modules a few years back.
There were a few more reasons too, at least at the time. The companies in the space didn't have a culture of open sourcing, and there's probably no perceived commercial upside to releasing code for a chip like that.
I think often it's also a combination of what you described and big companies being super risk-averse. Why risk breaking regulations if you can just say no?
Then again, lots of Wi-Fi-enabled devices support simply changing their region setting and will happily let you use different Wi-Fi bands or increase signal power.
True but those bands are still official wifi bands somewhere.
On software-defined radios you can often use them way out of spec, way more so than using a forbidden channel. But in a totally different band. A good example is the RTL-SDR stick which was designed to be a TV received but can be used as a wideband SDR these days. That's a receive-only device so it's not that critical to regulators. Once you can transmit, it becomes more of a problem.
An example of a more problematic transmission device is the Raspberry Pi PWM pin. That's been used to transmit all sorts of stuff on many bands. Because it was never designed to transmit anything, it causes all kinds of weird harmonics and artifacts. It's a really bad idea to use it for that. Most people just do it under controlled circumstances.
Surely it's possible to maintain control over that while still publishing the source code? Seems like security by obscurity.
The hardware itself is flexible and relies on software for things like calibration, setting frequencies, and setting power.
> Seems like security by obscurity.
There are legal standards to meet around protecting the system from users modifying things like output power. They don’t literally say that the source code must be private, of course, but keeping it closed source makes it much easier to demonstrate that you were not making it easy for people to exceed the regulatory limits.
If you document the registers for setting output power (for example) then you’re giving the end user a roadmap for changing output power.
I don't know, I don't think there are many open-source third-party firmware implementations for these kinds of chipsets out there, so it seems pretty well obscured.
Exactly my thoughts. To avoid out-of-regulation tweaking coudn't they just allow signed code to run? How can I be sure that this closed for, i.e. surveillance reasons? One can publish the source code and still prevent misuse afaik.
Many modern chips do in fact use signed firmware yes.
Technically they could publish the source in that case but I think some patents would prevent them from doing this. Radio stuff is riddled with patents. Also most likely the "why would we" reason. There is no benefit for the manufacturer.
Why would patents prevent open source? As in, they're afraid of patent trolls trawling their code for "infringements"?
If it's concerning their own patents, no need to hide the source code. A patent is literally "letters patent" or public description of an invention. Trade secrets on the other hand I could understand.
It's often a condition of licensing those patents. NDA's, they're huge in the radio and embedded world. It only became a bit more open when the Arduino and Raspberry projects came along. And even there it wasn't fully open, especially with the Raspberry because Broadcom is one of the worst offenders.
I'm surprised how much they were able to open source as-is. I think part of that is that the SoCs powering the raspberry are kinda 'old news', definitely not the bleeding edge kind of embedded tech. The first raspberry basically happened because Broadcom had a whole bunch of old chips they weren't able to sell. Only when it took off they started making some actually for the purpose.
To be fair, depending on your partnership you actually do get the code to these blobs, and export control comes into play.
To avoid intentionally or unintentionally interfering with frequency spectrum it should not be.
Not in Zephyr. There's a full BLE Controller in source code form there.
This smartwatch isn't really all that smart by today's standards.
I would really miss the mod cons I have on my current smartwatch. Payments over NFC, dual-band GPS tracking, 4G LTE connectivity. The Pebble (and repebble) trades all that in for a multi-week battery life. But the minor hassle of once-every-two-days charging on my galaxy watch really isn't enough to forego all these powerful features for me.
Conversely, I don't care about any of those features, and I do care about long battery life. It's great that different devices catering to different users exist. I don't think the fact that they are aiming at different users from you makes it "not smart", it just makes it not suitable for your use.
Same, I love Pebble and Pebble-like devices precisely because they have long battery life. I don't want or need payments on my watch. I'm also not a fitness junkie, so I don't use GPS tracking either. I mainly enjoy the well-designed UX Pebble provides and its simple functionality like alarms, stopwatch, and notifications.
With watches that need charging every one or two days, I get this Sisyphean feeling that I am owning a constantly dying device with a battery indicator that exists solely to be charged. The amount of functionality a watch can provide me (versus a smartphone) just doesn't justify the amount of charging I need to do.
Maybe I'm not a smartwatch power user like OP. But the Pebble and its ilk are a great fit for the niche audience I belong to.
There are other full featured smart watches like the Garmin Enduro 3 with several weeks of battery life (or even longer with solar charging). Of course it's larger and more expensive.
https://www.garmin.com/en-US/p/851039
No one really needs payments on their watch but I'm surprised that anyone wouldn't want it. It's quite convenient, and gives you a backup option in case you forget your wallet or something.
Don't get me wrong, I backed the first Pebble on kickstarter. Still have it. It was a great watch for the time. I loved it.
But these days I just have bigger requirements. The whole heartrate thing I don't even care about. Notifications are the main thing, but route tracking, integration with my alarm system and above all payments are just things I can't do without anymore. I had an Amazfit for a while which also had a 3-week battery life (though no apps) but it missed the payment option.
The charging is not a big deal for me because I only wear my watch outside anyway. And it charges in 30 minutes. It makes it easy for me to keep it charged also because it becomes a routine. With the amazfit it was often empty when I needed it.
But yeah it is great that there are devices for everyone.
> Notifications are the main thing
Maybe you mean types of notifications that I'm not used to using, because notifications were the first thing I would turn off on any smart watch I've used (pebble, Amazfit, galaxy). The last thing I need if to have yet another device (now being worn) vibrating every 5min for some message.
Truth be told I use the least smart feature of the watch: the alarm. I can set quite granular schedules for my alarms and that means no one else needs to wake up but me. The health tracking I barely care, but since I'm wearing it I track it. I could imagine using the payment feature tho, to avoid taking the phone out.
> Maybe you mean types of notifications that I'm not used to using, because notifications were the first thing I would turn off on any smart watch I've used (pebble, Amazfit, galaxy). The last thing I need if to have yet another device (now being worn) vibrating every 5min for some message.
At least on my smartwatch (Samsung one) I can choose which notifications I want to forward to the watch. And I have all the ones I don't care about turned off anyway, even on my phone. For me it replaces a lot of my smartphone (which I only use outdoors anyway, at home I have a real computer). The ability of the galaxy watch to also show pictures in notifications is a big plus (my old pebbles could not do that, not sure about the new repebbles)
The notifications on my watch are the main reason I have it. It avoids looking at my phone every time something comes in. It's not too often because I block so much and I don't use social media.
I don't care much about the health tracking, though I do sometimes use the sleep tracking. Especially the SpO2 tracking is handy because I have apnea. It does bother me that Samsung doesn't make it possible to turn off their health "gamifications" (every day I get nonsense messages like "Will you meet your goal today?", "You're halfway your goal, keep going!"). I still have to see if I can turn that crap off via ADB.
I'd add that it also ignores that Garmin already has multi-week battery life with most of these features and more. The only thing they don't have is 4G yet, but I believe next year's devices have been reported to have it.
I too would miss GPS, BUT I've still never found anything that really fills the pebble shaped hole in my life. My Garmin compromises the other stuff (battery, widgets, calendar, display readability etc.).
Everything is a trade off.
It is for me, I don't care about any of those features. I just want a watch I can customize a bit that gets notifications and can do rudimentary heart rate monitoring. If I have to charge it more than once a week I won't wear it.
The battery life alone suggests otherwise.
More information on the chip here: https://www.cnx-software.com/2025/05/14/sifli-sf32lb52j-big-...
Interesting they did not go with 2-chip design(1 for main application, 1 for BLE stuff). Which is sometime makes sense because high power mcu usually does not have RF
The "high-end" modern MCUs are pretty great, you have the NRF offerings, but also the likes of the ESP32 where you can get Bluetooth and WiFi in a single package.
Personally these days I would lean towards the ESP32, they continue to iterate on it nicely and it has great community support. I'm personally developing a smart watch platform based on micropython.
While the ESP32 is great for many applications, it’s not for battery operated stuff. When an nRF draws 1-2 mA when using BLE, ESP32 will draw 40 mA. And the chip they selected is even more efficient.
The low power chips can also run in low power mode without BLE running using micro amps, something the ESP can’t match.
I really like ESP32 and I hope they have a low power chip on their roadmap.
Sure I agree, but the WiFi functionality is a killer feature. As mentioned in another comment, it means a smart watch stops being a smart phone addition and can actually operate as a stand-alone device.
Years ago I had a "smart" watch that had a sim card and was a full mobile phone within its own right, I think it was just 10 years or so too early.
Concur. With nRF, you have to bolt on a separate 70002 Wi-Fi Chip.
And this chip isn't a normal QSPI chip where you read the datasheet. You have to use NRF connect, and Zephyr.
So, this brings up the obvious question: What if I don't want my whole firmware to be Zephyr nRF-connect, just for a Wi-Fi chip?
Manufacturer lock-in can be quite a problem. I'm not saying the ESP32 solves this fully, but you can mix and match as you like, and it's highly encouraged. I think with the ESP32 most build upon Free RTOS but I'm not aware of a strict requirement.
Of note, you can just pull in a lib to use Wi-Fi and BLE on an ESP32 (C-3 at least). I've done it. It doesn't imply any changes to your firmware architecture. That's the part that bothers me about Nordic's approach.
pretty sure you can use 7002 with any MCUs and vice versa. I dont know what would be the technical limitation
Aren't ESP32s way more power hungry than typical BT-only parts though?
Not insanely for a smart watch. Your smart watch battery will be something like 200mAh, so for 20 hours you need to average 10mAh. With zero optimisation, screen refresh rate at 30+fps, I have smart watch chewing 30mAh.
Getting down to 10mAh is not so bad. If you're not actively driving the display, you can under-clock significantly [1], if you're not using WiFi you can turn the modem off [2].
[1] https://docs.espressif.com/projects/esp-idf/en/stable/esp32/...
[2] https://docs.espressif.com/projects/esp-idf/en/stable/esp32/...
It might be just-about acceptable for a smartwatch. But anything the micro takes out of the power budget means less screen and radio time, which does add constraints.
PineTime, based on NRF52, will get you 4-7 days of practical usage.
There are ESP32 watches. One I have[1] comes with quite thick 940mAh battery but my understanding is the battery life still isn't that amazing (just got it, haven't really tested the battery) - something like less than a day of constant runtime or few days if you turn it off constantly
[1] https://lilygo.cc/products/t-watch-s3-plus
Yeah I got one of those as well. An the older non-S3 version. Fun for developing, very powerful. I use it for developing ML applications for watches etc (emlearn project). Great device for that, but battery life is not its strong point.
I have a similar one with a microphone, I dread to think how the GPS module and LoRa of that variant affects battery life!
Can confirm, I regularly get about 9 days of charge on my PineTime, running the latest PineTimeOS release. Its gotten better and better over the years, and the functionality keeps coming ..
I used to use the PineTime with PineTimeOS, but mine eventually broke (corroded inside), but not having WiFi made it annoying to develop for. With WiFi suddenly you don't need to communicate regularly with a phone and the possibilities really open up.
I get that kind of experience with the Watchy… but the problem is, its quite a bulky device and gets a bit tiring to wear after a while.
no, esp32(the original one) is insanely power hungry, especially its radio.
Also 20 hours of runtime is horrible.
I'm getting 10 hours run time with the screen continuously running and drawing graphics every refresh in micropython - extending this time out is definitely possible.
There are many ESP32 variants, depending on what you pick some may be more compelling for your use-case.
Well, we are talking about smartwatch use case.
Even some newer variant like S3 or C6 only has acceptable power consumption, if what you are after is run-time they are not the best fit.
Does this apply to C-3 and C-5 as well?
I would not consider ESP32 high-end MCU, it still lacks many peripheral(DSP, GPU), its core clock is not high(only 240mhz iirc).
Recently they release ESP32P4, with very strong performance, but like you guess, without Radio
We are talking about an MCU, not a CPU :)
I think once we start talking about GPU, MMU, USB, display, etc, we're getting towards a CPU of sorts.
Speaking of a low-end CPU, I want to test out the RV1103 Rockchip, those crazy little chips are running Linux apparently [1], and even able to run Python [2]. Depending on power draw, a Linux-based smart watch could be on the horizon.
[1] https://www.luckfox.com/EN-Luckfox-Pico
[2] https://wiki.luckfox.com/Luckfox-Pico/Luckfox-Pico-SDK
Yes, we are talking MCU, it's very common now that mcu has gpu now.
For ex: Bes2700bp and bes2800 has 3d GPU iirc. Their spec is very impressive, too bad that their SDK is kind of limited to non-Chinese vendor
USB is trivial for most modern MCUs; even low-power/minimal-cost ones.
ESP32-S3 has all that minus a GPU. Runs Linux.
Looking at that now [1], seems like something I need to run a test with!
[1] http://wiki.osll.ru/doku.php/etc:users:jcmvbkbc:linux-xtensa...
You got downvotes but im a firmware eng and can point out more esp deficiencies. #1 completely fake FPU that they lie aboutm. #2 awful memory bandwidth. Not only slow but unpredictable. #3 small onboard memory. #4 low clock speed.
The Cortex-M33 core in the SiFli chip will be much faster than the M4 cores that the fastest released Pebble watches used, so a faster MCU than this is not something that's needed. However, more battery life is very welcome, and the fact that they're using MCUs with integrated Bluetooth this time seems to be a huge part of the upgrade from about a week of battery life to about a month of battery life.
It's just a watch. You don't need a full UNIX computer to tell time, or to record heart rates or pinging AWS for those matters.
Interesting comment, because according to https://en.wikipedia.org/wiki/PDP-7 the PDP7 (the first computer "UNIX" ran on) had ~9.2KB of memory (supporting up to 144KB).
Most contemporary SoCs will have more memory (and compute power) than that.
That's a complete non sequitur. Just because UNIX can run on lower end hardware doesn't mean "a full UNIX computer" is the best tool for the job.
the more chips you have, the more complex the project becomes. BOM is one thing, every chip needs support passives and oscillators, but now you also need to coordinate communication between the chips, you need to devise a way to update firmwares and access both chips for debugging purposes... that might be worth to trade off for less battery life.
in my experience they are not that much difference between 2 design. The BLE FW is a binary blob that you will download at boot with 2 chip-design, or load it to correct address with single chip-design.
From the CPU perspective, they are the same
From a PCB layout and supply chain perspective, it’s a big difference.
> in my experience they are not that much difference between 2 design.
Depends!
If the two chips use UART or SPI for intercommunication, okay, you need two lines between the CPU and two GPIO lines for wakeup, and JTAG can be shared anyway.
But if you use stuff like shared memory, or want to do stuff like updating the display not just from the high-power chip but also from the low-power one, suddenly design becomes much more complex.
Glad to finaly see someone in the low-power chip industry going in the open source direction. Thanks for the insight!
When I saw rePebble be announced, I signed up for it right away. Only later I realized I actually don't want a smartwatch, I want a dumb watch with vibration notifications.
I know I'm in the minority, but it's a niche that has a few very interested people in it [0] [1] [2]
After wearing the Casio F105 for the past 2 years, I can't go back to something larger, heavier or thicker than this. I could accept weekly battery charging for the benefit of having some bluetooth functionality.
So nowadays I'm looking for a super small bluetooth chip that can power a small vibration motor, which can receive all notifications from my iPhone. I would like to glue that chip, motor and a small lithium battery between the two straps of my F105, because in my tests it seems I don't notice if I add a small weight there.
I still remember when I first used my first Mi Band 1, a forgotten fitness band that had no display, just 3 RGB LEDs that could even get specific colors based on the app that sent the notification. I could know right away when I got a blue Messenger chat that I needed to answer now, or a yellow Google Keep reminder that I could ignore until I got back to my computer.
[0] https://www.reddit.com/r/pebble/comments/9xw2j2/im_looking_f...
[1] https://www.reddit.com/r/smartwatch/comments/174hq9x/need_a_...
[2] https://tildes.net/~tech/18nf/smartwatch_primarily_for_notif...
This might be out of scope, but citizen makes the W770, I recently bought one for <200US lightly used. It manages to be a pretty good chronograph , BLE with an alarm and vibration motor (with a somewhat neglected strange little ecosystem of scriptable notifications).
As a watch, it does require that you read the manual completely to understand its various interface paradigms, but it’s reasonable given that there is no display per se, only hands, to show all of the information. Also, you may need to synchronize the hands at first setup, that baffled me at first lol.
It’s efficiently solar powered using a super capacitor, with months of battery life if left in the dark, no battery concerns at all if you wear it (unless maybe you are an actual vampire that also cannot tolerate artificial light)
The supercapacitor can be replaced if it wears out, seems to be reliable for about 15-20 years based on their other watches.
I like mine quite a lot, it’s a well built actual timepiece, put it on and forget about it if you want. It doesn’t ask you to do anything for it to just do its job, year after year.
Citizen may have other options as well with BLE, idk.
Id love to see someone reverse engineer the notification / BLE communication protocol and create an open source companion app - the possibilities for hacker-y types would be pretty cool.
I still rock my OG Pebble and while I am excited they're coming back, I have no plans to upgrade.
Like you, my needs are simple; vibrating alarm, notifications, but with one key factor; I need a display that I can read in broad daylight that plays nice with my far-sighted eyes. The eInk display on the OG Pebbles hits the mark. Being able to read a text without pulling out my phone is also nice.
Plus they can be got on eBay for about $30 USD and a fresh battery is about $15, so they don't break the bank. The Rebble.io community's work is still functioning well enough for my use, as well.
Small correction, pebbles use a TFT "e-paper" display, not e-ink. This is how they have reasonable refresh rates for animations and no after image problems. It's the best compromise imo
Ahh, right. Thank you, I do mix them up in my head often.
Same boat, Apple watch has terrible UX (1cm fingertip in a 2cm screen??!?), tries to do too much and not to my liking.
Pebble allows me to walk away from my phone because I will get the notifications (text or phone call) and can see enough to decide to respond.
Pebble is pretty lightweight and if you load up this watchface you'll feel right at home: https://store-beta.rebble.io/app/52f0939b1ac7948708001fc9
> I want a dumb watch with vibration notifications.
Same. Notifications are rarely time-critical. A few years ago I noticed that I kept getting distracted by my phone alerting to some nonsense which really didn't matter, so I completely disabled all notifications. I'll just look at it once every few hours to respond to incoming messages.
A regular smart watch would be pretty pointless for me. Getting stuff like message notifications on my wrist would be a huge anti-feature. However, it would be pretty nice to have a convenient way to set an alarm, which will vibrate on my wrist when it goes off. I want a "leave now to catch the bus" reminder, or a "it's time to take a break" reminder! That's all, nothing more, no need to add any fancy sensors.
> I kept getting distracted by my phone ... so I completely disabled all notifications
Couldn't you just disable notifications for the unimportant apps?
For me at least, it turns out there are no important ones.
I agree. I’ve been looking for a “smart” watch strap or strap clasp I can use with my vintage seiko watch. I just want vibration alerts when very specific things happen on my phone. My wife is calling etc. Dont need all the features or display of a typical smart watch. Too distracting.
Would Withings[1] watches not fit the bill? I have a ScanWatch and the battery life lasts almost a month.
1: https://www.withings.com/
I had a Seiko watch for decades that needed a new battery every 5 years, and I still miss it. It never left my wrist except for battery replacements. The Casio mentioned above goes one better by using solar, so it would never have to leave my wrist - and it has a BLE connection to the phone. But it doesn't have enough sensors, like an accelerometer.
Withings smartwatches come do closest, and that's what I have now. Their standout feature is their 30 day recharge, but they still have a ways to go.
They are expensive, but worse they are fragile and no one will repair them in most countries, and the rechargeable battery means they will only live a few years. On top of that I'd like to see them add NFC, payment card and passkey integration, with better security so if they leave you wrist you have to re-authenticate or reset them. None of these things require much (if any) power. Also while the analogue time is great, interacting with the digital interface is clunky. A single button is not enough. The digital interface could be bigger, and could display more - like displaying the last few message.
So my take is while smartwatches are improving, they still have a ways to go. And that way is not the direction Apple appears to be taking, which seems to be to put a power hungry iPhone with a miniature screen on your wrist. I'm hoping the old watch manufacturers will come back with their robust very low power designs, with a few added sensors.
The Scanwatch Light seems to be very close to what I need. While they're priced reasonably for what they offer, they're crazy expensive for what I would need. I'm really not interested in fitness or sleep tracking these days anymore.
I'm also a bit scared of the many "charging issues" some people seem to have with them after a few months, but I guess every batch has a few bad devices so I could hopefully return it.
Thanks for the recommendation! I might try one soon.
For what it’s worth, after I bought one, around five other people I know got them, varying models from the Steel HR to Nova, and haven’t been made aware of any issues. Of course, personal experience doesn’t apply to the mass of products, and these are all UK SKUs, so who knows if issues vary between countries as well?
Overall everyone has been happy though and I haven’t seen Withings come up on HN which is surprising tbh!
Apparent my wish for a fitness tracker that's not a watch is also pretty niche. I know that there are rings, but I also don't like rings.
Basically I want a bracelet, if it must be on my arm, but ideally it would be an ankle bracelet. I'm not sure that would provide a convenient spot to get heart rate, or data beyond steps.
Whoop.com, your wish has been granted! Just pony up $19.95/mo (or whatever) as well...
So close... but why the subscription? It just needs to stuff the data into Apple Health when it is within range of my phone.
It is actually tempting, but I can't support a subscription based hardware product. Just charge me whatever the device cost + profits.
I've had one since October and really like it.
I justify the ~$20/mo the same way I justify a gym membership: it's a bargain if it's compelling you to make positive choices about health/sleep/exercise. If it's not, then yeah, it's just an expensive mood ring.
Of course, there are also smart rings (Oura) and much cheaper devices (FitBit https://store.google.com/category/trackers).
Full disclosure, I worked many years at Fitbit, in a very senior role.
The reason you want Whoop to have a subscription (and why I wear a Whoop now) is because it incentivizes the company to ship great hardware _and_ software. If you don’t have a subscription, your company becomes stuck on the treadmill of needing to have a new device to sell to the public every year (or even twice a year) so that you can continue to fund your business. Pebble found this out, too, and it led to their sale eventually.
Worse, the launch dates are not movable. People are largely not going to wait and buy your new watch in January if they wanted to get a Christmas gift for their spouse. The same goes for Mother’s Day. The scope is also not movable, because it has to have certain things for people to be interested vs last year’s model. We all know what happens when you fix scope and date in the iron triangle — quality suffers.
The subscription model has a great property — you can ship the device to your customers when it’s ready and meets your quality bar, and you can theoretically do it for free, because they are already paying a subscription. I realize Whoop did not take this path with their latest device release, they are clearly trying to goose their revenue for a quarter or two. That said, at the end of the day, their full product offering will either earn your subscription or not, which means that you can be confident that they are aligned with your interests. You generally cannot say that about a pure hardware company, unless they are remarkably disciplined with respect to hiring. I have not seen an example of this in the wearable/health space.
I think you can derive a general principle from this, which is that if a company is incented to sell you crap, they will eventually do so. If instead they are required to repeatedly earn your business, they will either maintain high standards for their products or they will go out of business. I mostly choose to spend my money on products made by companies with the latter model.
NB that Whoop did pull a fast one on users. People signed up with the promise they wouldn’t have to pay for hardware upgrades. Whoop recently dropped that right before releasing their first hardware upgrade.
As per your last link, the current Mi Bands fill that niche pretty well. Screen, but decent battery life and small enough to not get in the way.
I started to hack around cheap chinese Freqchip SOCs:
https://github.com/zoobab/FR801xH
You could get smartwatches for 3EUR on Ali with this chip.
Wow, some of these chips are 2.6rmb at 3k MOQ ($0.36) for an Arm Cortex m3 with BLE (and sig-mesh) support... this is wild!!! How usable is the SDK?
BLE is fairly straightforward to implement. It's the compliance testing which is costly. Are these fully compliant, i.e. FCC approved?
Thank you for the write-up. Cool to see some degree of open-source hardware running PebbleOS.
Though, can we stop having left-aligned blogs in 2025? Wide screens have been here for a while, it makes it unnecessarily hard to read :(
> The most interesting and difficult constraint is actually software compatibility.
But it is probably the easiest constraint to get around. I would put this one more towards the end of the list.
There's two big factors that make software compatibility very important for this product specifically.
1. His team is positively tiny compared to what Pebble used to have, and the less software work that's needed, the better.
2. All of the apps and watchfaces people wrote for the original Pebbles were distributed as compiled ARM binaries, so if you picked an MCU with an entirely different instruction set, you'd lose backwards compatibility. ESP32 would fall into that category, for example (not that it would have been a good choice anyway).
There are solution for question 2. You can either add a compatibility layer to the software stack(something like Java VM), or people can build their app against your codebase, and your watch will dynamically load it and run(like how linux run their app). In Zephyr they have LLEXT for that.
I mean, these applications are by necessity very tiny. They must fit in a very small memory. Hence, I seriously question that it would take a lot of work to rewrite the software for a different architecture. You can reuse the entire graphical design (which is probably a large chunk of the work because designing for small screens is not easy).
A lot of them are closed source though.
Not at all. If everything is proprietary you will run into many dead ends. This is totally different than with e.g. standard PC hardware.
Love this write-up. nimBLE is a great bluetooth stack; this should open up some interesting opportunities for Core Devices moving forward.
@ericmigi these are great BTW, wish you did them during YC while we were going through all these decisions haha
Awesome feature set for that price.