TshWatch is a project by [Ivan / @pikot] that he’s been working on for the past two years. [Ivan] explains that he aims to create a tool meant to help you understand your body’s state. Noticing when you’re stressed, when you haven’t moved for too long, when your body’s temperature is elevated compared to average values – and later, processing patterns in yourself that you might not be consciously aware of. These are far-reaching goals that commercial products only strive towards.
At a glance it might look like a fitness tracker-like watch, but it’s a sensor-packed logging and measurement wearable – with a beautiful E-Ink screen and a nice orange wristband, equipped with the specific features he needs, capturing the data he’d like to have captured and sending it to a server he owns, and teaching him a whole new world of hardware – the lessons that he shares with us. He takes us through the design process over these two years – now on the fifth revision, with first three revisions breadboarded, the fourth getting its own PCBs and E-Ink along with a, and the fifth now in the works, having received some CAD assistance for battery placement planning. At our request, he has shared some pictures of the recent PCBs, too!
Most of the design and engineering required to improve the efficiency of the data logger involve standard practices for low-power devices such as shutting off unnecessary components and putting the device to sleep when not actively running, but this build goes far beyond that. The Vcc pin on the RTC was clipped which disables some of its internal logic but still keeps its basic functionality intact.
All of the voltage regulators were removed or disabled in favor of custom circuitry that doesn’t waste as much energy. The status and power LEDs were removed where possible, and the entire data logger is equipped with custom energy-efficient code as well.
If you’re starting a low-power project, even one that isn’t a datalogger, it’s worth checking out this build to see just how far you can go if you’re willing to hack at a PCB with cutting tools and a soldering iron. As to why this data logger needed such a low power requirement, it turns out it’s part of a kit being used in classrooms and using a coin cell brought the price of the entire unit down tremendously. Even if you have lithium cells on hand, though, it’s still worthwhile to check out the low power modes of your microcontroller.
[Hans Andersson] has been creating marvelous twisting timepieces for over a decade, and we’re pleased to be able to share his latest mechanical clock contraption with our readers, the Time Twister 5.
In contrast to his previous LEGO-based clocks, version five of the Time Twister uses 3D printed segments, undoubtedly providing greater flexibility in terms of aesthetics and function. Each digit is a mechanical display, five layers vertical and three segments horizontal, with a total of three unique faces. Each layer of each display can be individually rotated by a servo, and this arrangement allows for displaying any number between zero and nine. The whole show is controlled by an Arduino MEGA and a DS3231 real-time clock.
Watching these upended prisms rotate into legible fifteen-segment digits is enjoyable enough already, but the mechanical sound created by this timepiece in motion is arguably even more satisfying. Check out the video below to see (and hear) for yourself. If you want to build one yourself, all the details are here.
Most clocks these days have ditched the round face and instead prefer to tell time through the medium of 7-segment displays. [mihai.cuciuc] is bringing the round face to digital clocks with his time-keeping piece, MakeTime.
MakeTime serves two purposes, the first and most obvious one is as a clock. Rather than displaying the time with digits, MakeTime harkens back to round dial clocks by illuminating RGB LEDs along its perimeter to show the position of the minute and hour “hands”. By using 24 LEDs, MakeTime achieves a timing granularity of 2.5 minutes.
The second purpose is as a development platform. [mihai.cuciuc] designed the clock with hacking in mind, opting to build it with components that many are already familiar with, such as a DS3231 RTC and WS2812 LEDs. To make the entire thing Arduino compatible, the microcontroller is an AtMega 328P, that can be connected to through the micro-USB port and CH340 USB-UART IC. If MakeTime outlives its time as a clock, all of the unused GPIO of the 328P are broken out to a single pin header, allowing it to be repurposed in other projects for years to come.
When it comes to measuring time on microcontrollers, there’s plenty of ways to go about things. For most quick and dirty purposes, such as debounce delays or other wait states, merely counting away a few cycles of the main clock will serve the purpose. Accurate to the tens of milliseconds, they get the average utility jobs done without too much fuss.
However, many projects are far more exacting in their requirements. When you’re building a clock, or a datalogger, or anything that relies on a stable sense of passing time for more than a few minutes, you’ll want a Real Time Clock. So called due to their nature of dealing with real time, as we humans tend to conceive it, these devices take it upon themselves to provide timekeeping services with a high degree of accuracy. We’ve compiled a guide to common parts and their potential applications so you can get things right the first time, every time.
Why would anyone want to be confronted by a count of the number of seconds left until you’ve made 80 trips around the sun? We can think of plenty of reasons not to, but creator [Jia Xun Chai] thought it would be somehow motivating to see the seconds tick irretrievably by while going about his life. Thus the idea for “Lifeclocc” came to be, with its ten seven-segment displays and Teensy to tally up and display the number of seconds left in a nominal 80-year life. A DS3231 RTC module keeps it on track between power-offs. It’s not clear what happens when you hit your 80th birthday; we assume it rolls over and starts counting up as you start playing in the bonus round. No word either on what happens should you croak with time left on the clock. Answer these questions and many more by building one yourself, or you can just wait for the Kickstarter.
It took [Jia Xun] three years to develop Lifeclocc, during which time his personal life clock decreased by 94,608,000 seconds. We will say that the finished product, with its matte-finish PCB, makes a handsome timepiece. Circuit sculptor [Mohit Bhoite] took a less-angsty stab at a similar clock, the cute appearance of which is no doubt intended to blunt the pain of impending doom.
When you read “Arduino wristwatch”, you fall into the trap of envisioning an Arduino UNO clumsily strapped to someone’s wrist. [Marijo Blažević’s] creation is much more polished than that. A round circuit board holds two surface mount ICs and 12 LEDs. The whole thing looks nice fit snugly inside of a watch body. It isn’t a Rolex, but it does have considerable geek cred without being unwearable in polite company.
One IC is an AVR micro, of course. The other is a DS3231 real time clock with built-in crystal. A CR2032 keeps it all running. The main body, the outer ring, the bottom, and the buttons are 3D printed in PLA. The crystal and the band are the only mechanical parts not printed. The bill of materials shows a 36mm crystal and even provides links for all the parts.
You don’t want to run LEDs all the time because it is bad on the battery. When you press the button once, you get one of the LEDs to light to show the hours. Another press reads the minutes in units of 5 minutes. A third press shows you one of five LEDs to show how many minutes to add. For example, if the time is 9:26 you’d get LED 9 (hours), LED 5 for 25 minutes, and the third press would show LED 1 for 1 extra minute. If either of the minute indicators show 12 o’clock, that indicates zero minutes.
The exciting thing, of course, is that you can program it beyond the code on GitHub. Already it can tell time and display the temperature. You don’t have a lot of I/O, but you ought to be able to get some more options and maybe some flashy LED blinking patterns in if you try.