This is the LilyPad Arduino USB board, controlled by an ATmega32U4 with the Arduino bootloader.
It has a built in power supply socket and an on/off switch with the only extra piece of hardware you need to program the LilyPad USB is a micro-USB cable, since the new IC has built-in USB support.
LilyPad is a wearable e-textile technology developed by Leah Buechley and cooperatively designed by Leah and SparkFun.
LilyPad is nothing but an Arduino-programmed microcontroller and works similar to other Arduino boards available.
It comes in a round shape unlike other Arduino boards so that it could fit easily in wearables.
However, the ability of this board to be sewn down with the fabric or sensor through conductive thread puts it ahead and stands out of the boards available in the Arduino community.
There are 22 wide open pin-holes, appear around the edge of the whole rounded shape that is mainly used for the connection with the fabric and sensor through a conductive thread.
Out of these 22 pinholes, one is reserved for 5V, and one for ground.
The LilyPad Arduino incorporates 6 analog inputs that can also be used as digital I/O. They are marked as A0 through A5 on the board, providing 10 bits of resolution. It is important to note that, the analog inputs measure from ground to 5 volts, however, the upper end of their range can be modified using the analogReference() function.
The board contains 14 digital pins that can be employed as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions.
Like other boards in the Arduino, this Pad is programmed by Arduino IDE – an official software mainly used for programming the Arduino Boards, that is developed by Arduino.cc
The board comes with a wide voltage range and operates anywhere between 2.7 V to 5.5 V. The pins on the board come with the ability to control and handle the input or output of the attached device.
There are two ways to keep your Pad null and void: increase the operating voltage above 5.5 V or plug the power in reverse order.
As I mentioned earlier bootloader is used for storing the code and burning it on the board, however, you can also bypass the bootloader and program the ATmega328 using ICSP (In-Circuit Serial Programming) header.
LilyPad is really very handy for e-textile and wearable products, because of its small size.
Arduino Lilypad is used in IoT products and embedded projects as well.
The circular tabs covering the whole Pad at the edge are mainly used for the connection between Pad and wearable products.
