MI/O — The Watch Bejeweled Not with Diamonds, But Diodes, and Not with Rubies, But Resistors!

This ATmega328-powered watch puts in the overtime, doubling up as a diminutive development board!

Tom Fleet
12 days agoWearables

Let's not kid ourselves, we've all fallen a long way from the corporate policy on suitable office attire.

With coronavirus still leaving many people working from home, a number of us are likely rocking a wardrobe that would have most workplaces rethink the wording of the the casual Friday "recommendations."

Despite Zoom having set us free of shoes, socks and for some of us, slacks, there's one component that is still core to even the most casual clothing collection — the wrist-worn chrono dial that makes sure we don't miss the all-important, Monday morning meeting.

These days, appearances are from the waist up, and a well-placed watch can work wonders, even in the absence of a pair of pants!

Whatever his actual reasoning, Markus Bindhammer has spent some time thinking this all out, as he's seen fit to commit to the design and production of his own, slimmed down "smartwatch."

MI/O is lovingly laid out, proudly showing off the components that lead to its long lifetime. With a Microchip ATmega328 MCU at its heart, it's clear that the focus here is on function.

I must admit, I'm a bit puzzled as to why Bindhammer hasn't chosen to instead use the ATmega328P version of the part, with its PicoPower features leading to lower figures for power consumption! No matter, as it's simply a part number change, with the 328P being pin, package, and program compatible with its non-P suffixed sibling!

Most of the watches we see on the project pages these days are brilliant examples of just what is possible with the technology that we now find available to us as designers. We've got watches with WiFi and WhatsApp. Timers that tweet. Chronometers counting our calories. Talk about feature creep on something that has a design spec of "tick tock."

MI/O takes it back to basics, and looks at the individual functions of a watch, treating them as switchable functions in order to save power where needed.

A watch is meant to be a slimline affair. Having a large battery stowed behind the front facade of the watch is only going to serve to elevate the bulk of the unit to the point where it becomes an inconvenience, snagging and catching on clothing and such. Not to mention, the weight that comes with the Wh rating written on the cell can also be an undesirable feature when considering the qualities desirable in a wristwatch.

By completely powering down the OLED display and ATmega, as opposed to dropping the controller into a low-power mode, the M I/O spends most of its life with the RTC being the only part of the circuit that is powered. This method of power control is really quite effective — there's a huge amount of difference between even the lowest of power modes, and actual shutdown in nearly every MCU, so using an external, low-power way of sequencing things makes a lot of sense.

Before feature phones, there were feature watches!

Casio has always had some strong design energy. Growing up in the '80s and '90s meant we were treated to all manner of ideas of just what was missing from the world of watches. Some of these weird and wonderful suggestions seen below are barely the tip of the iceberg of what was available to the discerning technophile.

Perhaps released far before the world was ready for them, there was still some novelty in these ideas! Some of them even stood the test of time, and are now commonplace in our smartwatches.

Work's done — time for some hardware hacking!

With more to it than meets the eye, MI/O isn't just a run-of-the-mill watch. Flip it over and you'll find some extra functionality that lets you fill out your own feature sets, with the MI/O serving as the core for whatever creations you can come up with.

We can find a full complement of connectivity on the rear face of MI/O, including GPIO, I2C, SPI and the UART of the ATmega all to be found on the headers that fan out from the middle of the boards back face.

With features limited only by what you can fit onto your wrist, some examples already demonstrated by Bindhammer include a wing to allow MI/O to be powered externally by a Micro USB connection, and a simple but effective "reading light" extension. We can imagine all sorts of neat extensions that could allow for some really cool interaction, with enough I/O to support all the fun sensors and signal lines they might require!

Although we've not yet seen signs of any sources from Bindhammer, there's enough information available over on his project page, such that you could surely learn from his lessons and pull together your own personal take on his MI/O build.

Tom Fleet
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