In celebration of #MarchIsForMakers, an initiative to get more coders interested in building hardware, I started this 4-part introduction to wearable technology. Click here to see Part I of the series Getting Started with Wearables.
The microcontroller is the main app processor. Known as the MCU, microcontrollers run the programs that make wearables function. In choosing the right MCU for your project, there are a number of factors such as size, water tolerance, power, and wireless protocols to consider. Think about a project where you are designing a type of wristband. You would want your microcontroller to be smaller in scale, bendable, and acceptable to moisture (sweat) as well as curved surfaces (for movement). In that project, aesthetics are just as important as hardware.
Likewise, because microcontrollers need to connect with other devices, such as a running app on your phone or laptop, a wireless connection is vital. Some MCUs will be required to support certain wireless protocols such as ANT+, BLE (Bluetooth low energy) and/or IEE 802.15.4. Microcontrollers also operate at low-power to conserve battery life. To help conserve power, MCUs that come equipped with 32-bit ARM architecture are popular for achieving the best energy efficiency.
The Right MCU For You
Now that you know some basics about Microcontrollers, let’s discuss which ones would be great for your project. Although, Raspberry Pi and Arduino remain the most popular MCUs on the market, we will need ones that are smaller in scale, fashionably aesthetic, and acceptable to movement, liquid, and different surfaces. There are lots examples that are excellent for wearables. I chose my top six below:
Lilypad Arduino: Made in collaboration with SparkFun Electronics and Arduino, this washable MCU comes with light and temperature sensors, LED, vibrator motors, and speakers. The Lilypad is very beginner friendly and has a great learning community around that offers tutorials and project videos.
XADOW Mainboard: Different models of the XADOW come equipped with LED, BLE, barometer and light sensors, and acceleration detectors. What’s cool about the XADOW is that the MCU can be manufactured by scale in different sizes, so whether you need metal framing or a flexible wristband model, it can be customized.
FLORA: This sewable MCU is Arduino-based and comes in multiple mini sizes. Along with built-in USB support, different types of the model come with LED, GPS modules, JST battery connectors, and sensors for light, temperature, and motion. Like the Lilypad, what makes FLORA stand out is the community support. There are lots of tutorials, starter packs, and project books based on the MCU for beginners.
Tinylily Mini: The Tinyliy functions like the Lilypad but packs the 32 bit processor power at 1/12th of the size. The MCU is washable and sewable but comes barebones. Other components such as USB port, LED, sensors, and adaptors will need to be bought in a separate starter pack.
Squarewear 2.0: The 2.0 and mini versions are open-sourced and Arduino-based. Although the Arduino IDE is based in C, any language can be used to program Squarewear with a Arduino compiler (think Artoo for Ruby developers). This MCU comes equipped with an on board USB port for charging, light and temperature sensors, buzzers, and LED. The 2.0 version also has an on board lithium battery charger.
ARM Cortex-M: This MCU is for more advanced projects and those who don’t mind a bit of soldering. The Cortex-M operates with apps based on C/C++ and offers OS support. Being the most electronic based out of the others, it has a 32-bit processor, is designed for low power operation, BLE enabled, and comes with instructions for sleep modes and comprehensive debug features.
For those worried about price, most microcontrollers go from about $20-$30 USD depending on the brand and manufacturer. It’s always good to have a project in mind before investing in a MCU in order to make sure you get the right model with the proper features. Now that we discussed the brains, I’ll be moving on to sensors and data collection in Part III of this series on wearables. Keep watching for more updates!