Bare PCB Makes A Decent Homemade Smart Watch

September 3, 2023 by Lewin Day 15 Comments

These days, we live in a post-Dick Tracy world, where you can make a phone call with your fancy wristwatch, and lots more besides. [akashv44] has gone a simpler route, designing their own from scratch with a bare PCB design.

The build is based around the ESP-12E microcontroller, providing useful wireless connectivity that lets the watch interface with the outside world. The firmware makes queries of NTP servers and Yahoo’s weather API to collect time and weather data for display. It’s also capable of interacting with Blynk relay modules for controlling other equipment, which [akashv44] uses with lights and an air conditioner. The watch uses a small OLED display and a handful of small surface-mount tactile buttons for control. Power is courtesy of a small lithium-ion pouch cell, with charging handled by a TP4056 battery management IC.

It’s a simple smartwatch, but nonetheless one that teaches all kinds of useful skills in embedded development and design. It’s also funny to think how simple it is to build. A decade ago, before the ESP8266 was released, getting wireless connectivity in such a small package was a major engineering challenge. Even the Apple Watch didn’t come out until 2015! Food for thought.

Showing pulse oximeter and color sensor combining to measure oxygen in blood and skin tone

Perfecting The Pulse Oximeter

August 7, 2023 by Orlando Hoilett 28 Comments

We’re always looking for interesting biohacks here on Hackaday, and this new research article describing a calibrated pulse oximeter for different skin tones really caught our attention.

Pulse oximeters are handy little instruments that measure your blood oxygen saturation using photoplethysmography (PPG) and are a topic we’re no strangers to here at Hackaday. Given PPG is an optical technique, it stands to reason that its accuracy could be significantly affected by skin tone and that has been a major topic of discussion recently in the medical field. Given the noted issues with pulse oximeter accuracy, these researchers endeavored to create a better pulse oximeter by quantifying skin pigmentation and using that data to offset errors in the pulse oximeter measurements. A slick idea, but we think their results leave a lot to be desired.

Their idea sounds pretty straightforward enough. They created their own hardware to measure blood oxygen saturation, a smartwatch that includes red and infrared (IR) light-emitting diodes (LED) to illuminate the tissue just below the surface of the skin, and a photosensor for measuring the amount of light that reflects off the skin. But in addition to the standard pulse oximeter hardware, they also include a TCS34725 color sensor to quantify the user’s skin tone.

So what’s the issue? Well, the researchers mentioned calibrating their color sensor to a standard commercially-available dermatology instrument just to make sure their skin pigmentation values match a gold standard, but we can’t find that data, making it a bit hard to evaluate how accurate their color sensor actually is. That’s pretty crucial to their entire premise. And ultimately, their corrected blood oxygen values don’t really seem terribly promising either. For one individual, they reduced their error from 5.44% to 0.82% which seems great! But for another user, their error actually increases from 0.99% to 6.41%. Not so great. Is the problem in their color sensor calibration? Could be.

We know from personal experience that pulse oximeters are hard, so we applaud their efforts in tackling a major problem. Maybe the Hackaday community could help them out?

Open Source OLED Nametag Is Full Of Features

July 20, 2023 by Donald Papp 5 Comments

Ever wanted a sweet OLED nametag with fancy features like daylight readability, automatic brightness adjustment, GIF animation support, all-day runtime, easy web interface, and more? [TobleMiner]’s OLED Nametag is the project you want to keep an eye on in that case.

It’s still an early prototype, but the feature list looks great and works with a variety of OLED modules that are easily available. The enclosure can be 3D printed, and while there is very little spare room inside the housing, [TobleMiner] has clearly made the most of all available space. Some PCB fab houses offer component placement these days, and the board is designed with exactly that in mind.

We’ve seen a batteryless E-paper display make a serviceable nametag in the past, and while those offer high contrast and wide viewing angles, they lack the sort of features this project is bursting at the seams with. Affordable access to good components and the ability to have high-quality PCBs made on demand has really raised the bar in terms of what a hacker project can work with in recent years, and we love to see it expressed in projects like this one.

Modern Software Brings Back The Timex Datalink

July 18, 2023 by Tom Nardi 27 Comments

As much as some people on the Internet might like to think — no, Apple did not come up with the idea of the smart watch. Even if you ignore the calculator watches that we imagine a full 60% of Hackaday readers wore at one time or another in their lives, the Timex Datalink was already syncing with computers and pulling down the user’s list of appointments back in 1994 by decoding the pulses of light produced by a CRT monitor. Hey, it sounded like a good idea at the time.

Unfortunately, this idea hasn’t aged well. The technique doesn’t work on more modern displays, and naturally the companion software to generate the flashing patterns was written for Windows 3.1. But thanks to the reverse engineering efforts of [Synthead], you can now sync any version of the Timex Datalink to your computer using nothing more complex than the onboard LED of the Teensy LC or Raspberry Pi Pico.

There’s actually several different projects working together to make this happen. In place of a CRT, there was an official “Timex Datalink Notebook Adapter” back in the day that was designed to be used on laptops and featured a single blinking LED. That’s what [Synthead] has recreated with timex-datalink-arduino, allowing a microcontroller to stand in for this gadget and featuring 100% backwards compatibility with the original Datalink software.

Appointment data is loaded from a text file.

But since you’re probably not rocking Windows 3.1 anymore, having access to that software is far from a given. That’s why [Synthead] also created timex_datalink_client, which is a Ruby library that lets you generate data fit for upload into the Timex Datalink. At the time of this writing there doesn’t seem to be a friendly user interface (graphical or otherwise) for this software, but it’s easy enough to feed data into it using plain-text configuration files.

Helpfully [Synthead] provides screenshots of information loaded into the original software, followed by a config file example that accomplishes the same thing. It looks like writing some glue code that pulls your schedule from whatever service you fancy and formats it for the Datalink client should be relatively simple.

We’ve previously seen projects that got the Timex Datalink synced without the need for a CRT, but they still required the original software. To our knowledge, this is the first complete implementation of the Datalink protocol that doesn’t rely on any original hardware or software. Expect eBay prices to go up accordingly.

Watch Hides Gesture Controls In Wristband

June 25, 2023 by Bryan Cockfield No comments

Over the last five to ten years, smart watches have become fairly ubiquitous, with the Apple Watch being among the most prominent of them. Not everyone wants or needs all of the capabilities of these devices, though; plenty are still opting for simpler devices which only have a few functions built into them. [Josh] has been working on one of these devices but takes a major design cue from their smart counterparts with the addition of gesture controls for the watch built into the wristband instead of relying on a more traditional button interface.

The watch hosts most of the functionality of a non-smart digital watch, with a timer, alarms, and a stop watch built-in. To change the time or access any of these functions, a combination of resistive and capacitive touch sensors are built into the wristband near the watch face. The combination of sensors aims to use the benefits of either type of sensor, with the capacitive sensors being used for precision and gesture recognition and the resistive sensors being used for pressure sensitivity. Placing these sensors in the band instead of the watch face improves visibility as well, since the screen won’t be obscured by the user touching the screen.

[Josh] originally intended this type of watch to be used for those with prosthetics or other disabilities which would limit the ability to use standard watch buttons or interact with a touch screen on the watch face itself. The device is working quite well as can be seen in the video linked below, but is still in the prototyping phase and under active development. For finishing up the final versions, we’d recommend taking a look at the design of these open-source smart watches for their high quality fit and finish.

Continue reading “Watch Hides Gesture Controls In Wristband” →

A wristwatch based on a red PCB with seven-segment LCD screens

The Time Machine Mk. 8 Is A Sleek Smartwatch With Retro Styling

June 11, 2023 by Robin Kearey 16 Comments

The primary purpose of a wristwatch is to tell the time, which pretty much any watch does perfectly fine. It’s in the aesthetics, as well as features other than time-telling, where a watchmaker can really make their product stand out from the rest. Watchmaker and electronic artist [Eric Min] focused on those two areas when he designed the Time Machine Mk.8, which combines exquisite design with simple, offline smartwatch functionality.

The heart of the watch is a Microchip ATSAMD21G18 low-power 32-bit microcontroller. [Eric] chose it for its high performance, ease of use and large number of integrated peripherals, a real-time clock being one of them. With the basic clock function thus taken care of, he then decided to add several useful sensors: a battery fuel gauge to keep an eye on the 40 mAh rechargeable lithium cell, a three-axis accelerometer to enable motion sensing and an environmental sensor to track temperature, humidity and pressure.

The various functions are operated using four pushbuttons along with a 16-step rotary encoder set in the middle. The overall design of the watch is inspired by Formula 1 steering wheels, as well as various sports cars and media franchises like Neon Genesis Evangelion and Akira. [Eric] considered a few different options for the display but eventually settled on two four-digit seven-segment LCDs, which fit nicely into the retro-futuristic aesthetic of the Mk.8. It’s so retro, in fact, that it almost makes [Eric]’s faux 1980s magazine ad look genuine.

All components neatly fit together on a dual-layer PCB, which is a true work of art in itself. From the lightning bolt on the front to the hidden Frank Sinatra lyrics, it definitely stands out from the crowd of ordinary LCD wristwatches. It’s also quite a step up from [Eric]’s previous watch design, the Time Machine Mk.IV.

Over the years we’ve seen several other examples of how a bare PCB, or even a stack of them, can become a beautiful wristwatch.

Apple Invent The Mechanical Watch

June 8, 2023 by Jenny List 38 Comments

The Apple Watch has been on the market for long enough that its earlier iterations are now unsupported. Where some see little more than e-waste others see an opportunity, as has [NanoRobotGeek] with this mechanical watch conversion on a first-generation model.

What makes this build so special is its attention to detail. Into the Apple Watchcase has gone a Seiko movement, but it hasn’t merely been dropped into place. It uses the original Apple watch stem which is offset, so he’s had to create a linkage and a tiny pulley system to transfer the forces from one to the other. The rotor is custom-machined with am Apple logo, and the new watch face is a piece of laser-cut and heat treated zirconium. Even the watch movement itself needed a small modification to weaken the stem spring and allow the linkage to operate it.

The build is a long one with many steps, and we’re being honest when we say it would put our meager tiny machining skills to an extreme test. Sit down and take your time reading it, it really is a treat. Apple Watches may head to the tip after five years, but not this one!

See more in the video below the break, and of course long-time readers may remember we’ve considered the Apple Watch versus mechanical watches before.

Continue reading “Apple Invent The Mechanical Watch” →