Review of Open Source Wearable Platforms

Open source wearable platforms have, in a big way, propelled the advancement of hardware and software development in the electronics field. Apart from making it possible for people to come up with innovative wearable devices, they have led to the production of efficient, miniaturised, low-power circuits that can be used in other applications. Some of those applications include sensor data logging among others.

There are several open source wearable platforms that one can choose from. They may be manufactured by different companies, but their operation is more or less the same. In addition to this, they are based on a popular open source programming platform, Arduino. However, this does not make them completely identical. There are several things that separate them. Understanding those things will enable you to make an informed choice. Here is a review of some of the common open source wearable platforms.

Flora

The FLORA is a popular wearable electronics platform designed by Adafruit industries. It is a round Arduino-compatible board that can be sewn on clothes and other textile pieces. There are several features of the FLORA that make it ideal for wearable projects.

To start with is its size, the FLORA is 1.8 inches in diameter, which makes it small enough to attach to a garment.

It has a round shape which allows the pins to be well spread around the board avoiding congestion. The increase in space between the pins ensures that they have large pads that make it easy for one to connect stainless steel thread to the board. This eliminates the need for wires and soldering. The FLORA can be sewn onto textile. So you don’t have to look for other attachment methods such as adhesive or Velcro.

The FLORA runs on the ATMega 32U4 microcontroller which has 28k of Flash memory and 2.5kb SRAM. This makes it ideal for bigger projects. In addition to this, it has 8 I/O pins that allow you to connect several FLORA-compatible sensor boards. Examples of the sensor boards include GPS sensor, motion sensor, light sensor and addressable LED pixels among several others. So you can use it for many applications.

Powering the FLORA is done via an onboard power regulator. This gives you a wide range of input voltage, between 3v and 16v. It also has a power switch that is connected to a 2A power FET for safe ON/OFF switching. So, you don’t have to worry about switch failure.

Gemma

Gemma is like the small brother to FLORA. It is also designed by Adafruit industries and has a 1 inch diameter. It is powered by the ATtiny85 microcontroller and is Arduino compatible. Concerning the size, the Gemma is 1.1 inches in diameter

Just like most open source wearable platforms, Gemma is round in shape and this gives it large space for its pins. The pads are large, which makes it easy for one to use stainless steel thread. Due to its small size, it has 3 I/O pins. So, you can only attach a few additional electronic components to it.

As stated before, the Gemma runs on the ATtiny85 microcontroller which has 8k of flash and 512 bytes of SRAM. This means that you can only upload small sketches that are ideal for simple applications.

On the downside, Gemma can only support a few simple sensors such as the pressure sensitive velostat among several others. Its 8k flash memory is also inadequate and can only hold very small sketches. This limits the number of applications it can do.

In addition to this, Gemma does not have a serial port. It cannot send data back to the computer via USB. Therefore, you have to use another board that has a serial port to calibrate your sensor values before transferring the code to your Gemma board. Also, its boot loader is not recognisable when the board is connected to USB v3 ports.

The Gemma does not have an on board power switch. However, it has a voltage regulator and reverse-polarity, current-limit and thermal protection. So, you don’t have to worry about connecting the battery terminals in reverse. The board can handle up to 16v input.

Trinket

The Trinket is another wearable platform that is designed by Adafruit. Just like the Gemma, it has an ATtiny85 microcontroller. This makes it very small and ideal for wearable projects and to top it all, it is the cheapest of the 3 Adafruit industries open source wearable platforms. The Trinket is 1.2 inches long by 0.6 inches wide

The Trinket is rectangular in shape. The pins are close together and their pads are small. Therefore, you cannot use the stainless steel thread with the Trinket. It has 5 I/O pins. Some of them are analog input pins and PMW analog output pins.

The ATtiny85, which is the Trinkets microcontroller, has 8k Flash memory and 512 bytes SRAM. It can only store small sketches and support a limited number of applications.

There are two versions of the Trinket. There is the 3V and the 5V version. Just as the names suggest, the two versions operate on different logic voltages, 3v and 5v respectively. The 3v version runs at 8 MHz and is ideal for applications that involve sensors that operate on 3v logic and when powering the board from a lipo battery. On the other hand, the 5v version runs at either 8 MHz or 16 MHz and is ideal in applications that involve the use of sensors that operate on 5v logic.

The Trinket shares the same disadvantages as the Gemma. It has no serial port connection and some computer USB v3 ports don’t recognise its boot loader.

There is a voltage regulator onboard. So one can apply as much as 16v to the board without risking damage. Apart from the voltage regulator, the Trinket also has reverse polarity, current-limit and thermal protection.

Lilypad

The LilyPad Arduino is a round, sewable board that runs on the ATmega328P or ATmega168 microcontroller. There are several variations of the board that can also be used in wearable projects. They are the LilyPad Arduino Simple Board and the Lilypad Arduino USB – Atmega32U4 board. Both boards have fewer pins (5 digital I/O pins and 4 analog I/O pins), and the Atmega32U4 board runs on the ATmega32U4 chip and has a USB port onboard.

The Lilypad is 2 inches in diameter and is round in shape and has 20 I/O pins – 14 digital pins and 6 analog pins. It has large connecting pads so you can use conductive thread to connect sensors and actuators to the board. In addition to this, the LilyPad is washable. Therefore, you don’t have to disconnect it every time you want to wash your garment. However, remember to disconnect the power supply before washing.

One down side is that it does not have a USB port on board. Therefore, you have to connect an FTDI breakout board to program it.

The LilyPad has the ATmega168v or ATmega328V which has 16kb flash memory. Though this is half the size of Flash memory FLORA has, the LilyPad can still handle moderately big sketches and applications. As is characteristic of most open source wearable platforms, there sensor modules and actuators that are designed to work with the LilyPad. Some of them include the buzzer, slide switch, push button, light sensor and LEDs among several others.

The operating voltage for the LilyPad is between 2.7v and 5.5v. The board does not have an onboard voltage regulator or protection circuit. So, you must make sure that you do not power it with more than 5.5v or plug the battery terminals inversely because that will damage the board.

Tiny circuits

Now, if you are looking for a very tiny board, the TinyLily is what you need. It is a very small Arduino-compatible open source wearable platform that is manufactured by a company called Tiny Circuits. It resembles the LilyPad but is 1/12th of its size.

TinyLily is round and has 8 I/O pins and 4 power pins. It has small pads on its pins which make it easy for one to use a conductive thread to connect it to sensors actuators and other electronic components. The TinyLily is also washable. This reduces the hassle of disconnecting it every time you need to wash the garment it’s attached to.

Just like the LilyPad, it lacks a USB port and you need to have an USB breakout board to program it.

Well, for a board its size it’s got a lot of potential, seeing that it has an ATmega328p microprocessor. With the 32kb of Flash memory and 2kb of SRAM you can do a lot with this tiny board. It also has some few compatible components such as LEDs a switch and battery adapter that you can use to increase its functionality

The TinyLily has no onboard power regulator or protection circuit. Therefore, if you connect more than 5.5v power or interchange the battery terminals you will damage the board.

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