The MKRZero brings you the power of a Zero in the smaller format established by the MKR form factor. The MKRZero board acts as a great educational tool for learning about 32-bit application development. It has an on-board SD connector with dedicated SPI interfaces (SPI1) that allows you to play with files with no extra hardware! The board is powered by Atmel’s SAMD21 MCU, which features a 32-bit ARM Cortex® M0+ core. Warning: Unlike most Arduino & Genuino boards, the MKRZero runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Applying voltages higher than 3.3V to any I/O pin could damage the board. The board contains everything needed to support the microcontroller; simply connect it to a computer with a micro-USB cable or power it by a LiPo battery. The battery voltage can also be monitored since a connection between the battery and the analog converter of the board exists.On-board SD The on- board SD connector allows you to play with files without adding any extra hardware to the board. Furthermore SD card is driven by a dedicated SPI interface (SPI1) and so any of the pins of the header is busy during SD usage. The SD library automatically recognizes the MKRZero and so any modification to the sketch is needed to use it aprat from choosing the right SS pin (SDCARD_SS_PIN). Battery capacity Li-Po batteries are charged up to 4,2V with a current that is usually half of the nominal capacity (C/2). For Arduino / Genuino MKRZero we use a specialized chip that has a preset charging current of 350mAh. This means that the MINIMUM capacity of the Li-Po battery should be 700 mAh. Smaller cells will be damaged by this current and may overheat, develop internal gasses and explode, setting on fire the surroundings. We strongly recommend that you select a Li-Po battery of at least 700mAh capacity. A bigger cell will take more time to charge, but won't be harmed or overheated. The chip is programmed .