A Solar-Powered Wristwatch With An ATtiny13

March 13, 2024 by Maya Posch 22 Comments

Wristwatches come in many shapes, sizes, and types, but most still have at least one thing in common: they feature a battery that needs to be swapped or recharged somewhere been every other day and every few years. A rare few integrate a solar panel that keeps the internal battery at least somewhat topped up, as environmental light permits.

This “Perpetual” wristwatch designed by [Serhii Trush] aims to keep digitally ticking along using nothing but the integrated photodiodes, a rechargeable LIR2430 cell, and a power-sipping face that uses one LED for each hour of the day.

The face of the perpetual wristwatch. (Credit: Serhii Trush)

The wristwatch’s operation is demonstrated in the linked video (in Ukrainian, auto-generated subtitles available): to read out the current time, the button in the center is pressed, which first shows the hour, then the minutes (in 5 minute intervals).

After this the ATtiny13 MCU goes back to sleep, briefly waking up every 0.5 seconds to update the time, which explains why there’s no RTC crystal. The 12 BPW34S photodiodes are enough to provide 2 mA at 0.5 V in full sunlight, which together keep the LIR2430 cell charged via a Zener diode.

As far as minimalistic yet practical designs go, this one is pretty hard to beat. If you wish to make your own, all of the design files and firmware are provided on the GitHub page.

Although we certainly do like the exposed components, it would be interesting to see this technique paired with the PCB watch face we covered recently.

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Watch on the wrist, with all the sensors facing the camera. There's a lot of them, and a lot of wires of all kinds tying everything together.

2022 Cyberdeck Contest: IP00-Minus, A Daring Wearable

October 4, 2022 by Arya Voronova 10 Comments

[Rob]’s IP00-Minus watch stands out on the Cyberdeck Contest project list page; it’s clear he decided to go a different path than most other hackers, and we can certainly see the advantages. For example, if there’s no case, there’s no need to redesign it each time you want to add a module — and [Rob] has added many, many modules to this watch.

Picking between regular LCD, memory LCD, and OLED displays can be a tricky decision to make when planning out your gadget, so he just added all three. The CircuitPython firmware initially attempted to resist the trio, but was eventually defeated through patching. Jokes aside, we can almost feel the joy that [Rob] must have felt after having put this watch on for the first time, and this project has some serious creative potential for a hacker.

[Rob] has been focusing on day-to-day usability first and foremost, with pleasantly clicky encoders, impeccable performance of its watch duty, unparalleled expandability, and comfortable wrist fit — it provides a feeling no commercial wearable could bring.

Out of the myriad of sensors, the air quality sensor has been the most useful so far, letting him know when to open a window or leave a particularly crowded place. The ESP32-S3 powered watch has been quite a playground for [Rob]’s software experiments, and given the sheer variety of hardware attached, we’re sure it will bring unexpected synergy-driven ideas. Plus, it’s no doubt a great conversation starter in nerd and non-nerd circles alike.

Good things happen when you give hackers a wrist-worn watch full of sensors, whether it’s a particularly impressive event badge, a modified firmware for an open source smartwatch, or a custom piece that pushes the envelope of DIY hardware.

Put 3D Metal Printing Services To The Test, By Making A Watch

August 18, 2022 by Jenny List 17 Comments

Have you ever been tempted by those metal 3D printing services? [Carter Hurd] has, and puts them to the test with a wristwatch. (Video, embedded below.)

It’s fair to say that among Hackaday readers you will find a very high percentage of 3D printer ownership compared to the general population, but for most of us that means an FDM or perhaps even an SLA printer. These two technologies have both effectively delivered polymer printing at the affordable end of the market, but as readers will also be aware they are only the tip of the 3D printing iceberg. We know the awesomeness of your industrial 3D printer is defined by the size of your wallet, and while our wallets are small, we are offered a chance at the big time through the services of rapid prototyping companies that will print our models on these high-end machines. Thus [Carter]’s project video is as much about using these services as it is about making a wristwatch.

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A wristwatch similar to the Berlin Uhr, with the actual Berlin Urh in the background

Tiny Berlin Clock Replica Also Counts Seconds

July 5, 2022 by Robin Kearey 7 Comments

If you’re a clock aficionado and have ever visited Berlin, you’re probably familiar with the Berlin Clock on Budapester Straße: a minimalist design of yellow and orange lights that displays the time in a base-5 number system. This clock has been telling the time to the few that can read it since 1975, and is but one of several unusual clocks that can be found in the city.

Berlin resident [jjoeff] decided to make a miniature replica, appropriately called the Berlin Uhr Nano, in order to watch the unusual display at any time of day. Built around a Wemos D1 Mini, it connects to WiFi in order to synchronize its internal clock to an NTP time server. It then drives a custom PCB that holds 39 WS2812 LEDs to display the time in its proper format. Unlike the original though, it also includes a full counter to tell the number of seconds; the bigger clock just flashes a single lamp to show the seconds passing.

Powered by a 500 mAh lithium battery, it can be converted into a wristwatch by simply threading a strap through slots in the PCB. With no buttons for adjustment or any functionality other than displaying the time, it serves the same purpose as the original, just in a portable format. We’ve seen a slightly larger Berlin Clock replica made of wood before, as well as a round one that uses the same base-5 encoding scheme. Continue reading “Tiny Berlin Clock Replica Also Counts Seconds” →

Wristwatch PCB Swaps Must Be In The Air

August 8, 2021 by Mike Szczys 19 Comments

Are we seeing more wristwatch PCB swapping projects because more people are working on them, or because we saw one and they’re on our mind? The world may never know, but when it comes to design constraints, there’s a pretty fun challenge here both in fitting your electronic wizardry inside the confines of an injection molded case, and in the power budget to make your creation run on a sippy straw of battery power.

Just this morning we came across [Joey Castillo’s] sensor-watch project. He chose the Casio F-91W as the donor wristwatch. It’s got that classic Casio look of a segment LCD display capable of displaying hours, minutes, and seconds, as well as day and date. But the added bonus is that we know these have decent water resistance while still providing three buttons for user input. Sure, it’s less buttons than the pink calculator watch we saw [Dave Darko] working on earlier in the week, but which would you trust in the pool?

Replacement PCB sized to use the same battery contact and CR2016 for power [via @josecastillo]

We see that [Joey] also chose to use the ATSAML22 microcontroller and sheds some light on why: it includes a built-in segment LCD controller! If you’re a peripheral geek like us, you can read about the SLCD controller on page 924 of the datasheet (PDF), it’s a whole datasheet onto itself.

The sensor part of the sensor-watch is a flex PCB breakout that allows you to swap in whatever sensor fits your needs. The first to be reflowed at [Joey’s] bench is a BME280 humidity sensor, which is most obviously useful for the included temperature measurements, but maybe it could also alarm at moisture ingress? [Joey] says you can swap in other parts as long as they’re in the QFN or LGA size range. We think an IMU is in order since there’s a lot of fun interaction there like the watch reacting to being positioned in front of your face, or to take tap-based inputs.

We think beginning with a donor watch is brilliant since pulling off a case, especially one that keeps water out, is 97% of the battle. But when your UI is unique to the watch world, sometimes you need to start from scratch like this wooden word clock wristwatch.

Do Wristwatches Get Any Better Than A Cuckoo Clock?

June 5, 2021 by Jenny List 10 Comments

There are few better ways of asserting your independent spirit as a hardware hacker than by creating your own special timepiece. Even more so if the timepiece is a watch, particularly in this era of smartwatches. Few home-made timepieces though have come as near to wristwatch Nirvana as the cuckoo clock wristwatch from [Kiyotaka Akasaka], which we would venture to name as having won wristwatches. Nobody will top this one in the field of home-made clocks!

Superlatives aside, this is an electronic cuckoo clock on the wrist, with an LED ring dial and a motorised cuckoo, all clothed in an authentically rustic tiny wooden cuckoo clock case. It communicates via BLE with a smartphone, and even has a sound channel for a cuckoo sound. Frustratingly there’s little in the way of detail about the electronics themselves, but we’re guessing that almost Bluetooth-capable microcontroller could be pressed into service. Take a look at the video below the break.

So we’ve established that it’s a cuckoo clock wristwatch, and that we like it, a lot. It is however not the only novelty cuckoo clock we’ve brought you.

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Modding A Casio W800-H With A Countdown Timer

April 30, 2021 by Lewin Day 28 Comments

Stock, the Casio W800-H wristwatch ships with dual time modes, multiple alarms, and a stopwatch – useful features for some. However, more is possible if you just know where to look. [Ian] decided to dive under the hood and enable a countdown timer feature hidden from the factory.

The hack involves popping open the case of the watch and exposing the back of the main PCB. There, a series of jumpers control various features. [Ian]’s theory is that this allows Casio to save on manufacturing costs by sharing one basic PCB between a variety of watches and enabling features via the jumper selection. With a little solder wick, a jumper pad can be disconnected, enabling the hidden countdown feature. Other features, such as the multiple alarms, can be disabled in the same way with other jumpers, suggesting lower-feature models use this same board too.

It’s a useful trick that means [Ian] now always has a countdown timer on his wrist when he needs it. Excuses for over-boiling the eggs will now be much harder to come by, but we’re sure he can deal. Of course, watch hacks don’t have to be electronic – as this custom transparent case for an Apple Watch demonstrates. Video after the break.

Continue reading “Modding A Casio W800-H With A Countdown Timer” →