TinyLily Mini review

Need a microcontroller for a tiny wearable project? Break out your magnifying glass! The TinyLily Mini by TinyCircuits is an ultra-compact Arduino-compatible microcontroller designed for e-textiles. But don’t be fooled by its size – with an Atmel Atmega328P on board (the same processor as Arduino Uno and LilyPad), the TinyLily Mini can drive complex projects and be hidden in the smallest wearables.

At one twelfth the size of a standard Arduino Uno, the TinyLily Mini is smaller than a 1p coin and smaller than a CR2032 battery. In fact it’s so small, it’s easy to lose – so keep it inside its plastic bag until you’re ready to sew it to something. How could a microcontroller the size of a breath mint possibly compete with a full size Arduino? We put the TinyLily Mini through its paces to find out if this tiny board measures up.

What You Get

The TinyLily Mini is available on its own for $9.28, or as part of a kit. We opted for the Starter Kit ($39.95) which comes with two TinyLily Mini processor boards, a USB adapter for programming, a battery connector, six sewable LEDs, and one incredibly tiny sewable button. That’s more than enough bits and pieces to create some interesting wearables, and more components are available on the TinyCircuits website. The kit also comes with a quick start guide, which is very handy for programming the TinyLily Mini for the first time.

06 TinyLily

The kit does not come with a battery, and it’s worth noting that the included battery connector uses a JST-SH connector, which is smaller than the standard JST-PH connector on many LiPo batteries. If your LiPo batteries came from SparkFun or Adafruit, chances are they will not fit the TinyLily battery connector, and you’ll want to purchase a new battery from TinyCircuits.

Although it doesn’t come with the starter kit, TinyCircuits also makes a motor shield for TinyLily, which can drive one DC brushed motor. And, because the TinyLily Mini is Arduino-compatible, you can use it with other Arduino-compatible wearable components, like Adafruit’s popular NeoPixels and SparkFun’s LilyPad modules.

You Probably Already Know How To Use It

Aside from its size, the TinyLily Mini shares the same form factor as many other microcontrollers designed for e-textiles. Its familiar circular shape and sew tabs are clearly inspired by Leah Buechley’s iconic LilyPad Arduino. If you’ve used other wearable boards like LilyPad or Adafruit’s Flora, you’ll be up and running with TinyLily in no time. Programming with the Arduino IDE is pretty standard, just select ‘Arduino Pro or Pro Mini (3.3 V, 8MHz) w/ATmega328’ in the boards menu, and upload your code.

There are eight sewable I/O pins on the processor board; four are digital pins and four are analogue/digital pins. Two pairs of sewable power and ground tabs are conveniently located at the top and bottom of the board. And if that’s not enough, there are more solderable pins on the back of the board: three more I/O pins, reset, VCC, and GND. That’s an impressive amount of capability for such a compact design, and the solder-friendly gold-plated tabs mean this board is useful for more than just e-textile applications.

Form Versus Function

To achieve its tiny size, some convenient features that are standard on other wearable boards were off-loaded to separate modules, such as a JST battery connector and a USB adapter for programming. If you want a reset button or on/off switch (highly recommended for any wearable project) you’ll have to add these to your circuit on your own. This is fine for many wearable projects, where you’ll want to customise the locations of these components anyway.

Keep in mind that although the board itself is tiny, adding the battery connector increases its size, and the connection is a little awkward. The battery connector plugs into the board face-down, which means the connector doesn’t lie flat against the surface of the project. This is more of an annoyance than a problem, but you’ll want to plan around it in your wearable designs, as the connector has corners that could scratch fabric or skin. TinyLily Mini has no power regulator, so be sure your power source is within the 2.7 V – 5.5 V operating voltage. Trading convenience for customisation means this board is less beginner-friendly than other wearable boards, and more suited to makers who are already comfortable with e-textiles and Arduino.

The sew tabs on the TinyLily Mini are definitely small, but they’re easy to sew to, and require fewer stitches to fill with conductive thread for a good connection. The sew tabs are labelled on the back of the board, likely due to lack of space on the front, and this makes it a bit tricky to be sure that you are sewing to the correct pin. It really helps to use a very small dab of hot glue to hold these tiny components in place while you sew. The board is washable, however you’ll want to take care not to bend or snag the male five-pin connector when washing.

Small, Modular, and Powerful

While other hardware companies are adding more features to their microcontrollers, TinyCircuits has stripped features away to create a board that is efficient and effective. Removing non-essential components from the main board results in a system that is customisable for every project. Small components like those in the TinyLily family make it easy to distribute your circuit invisibly throughout your wearable as you see fit, without having to sacrifice function. While it’s not the board we’d recommend for your first project, the trade-off in convenience is easily worth it for intermediate and advanced makers seeking to fit electronic circuits invisibly into their wearables.

TinyCircuits $9.28 tinycircuits.com

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