EnviroDIY Mayfly Data Logger Board v0.5 A powerful, user-programmable microprocessor board that is fully compatible with the Arduino IDE software. It features the ATmega1284p processor, which is much more powerful than the 328p chip found on most other Arduino boards. It has 4 times more flash memory for sketches, 8 times more RAM, and almost twice as many input pins. Features: 128K Flash memory, 16K RAM 28 digital I/O pins, 8 analog pins, plus 4 additional high-resolution ADC pins 2 serial UART ports microSD memory card socket Onboard realtime clock (RTC) (DS3231) Solar lipo battery charging Bee module socket 2 LEDs, 1 user programmable pushbutton 3.3v main board voltage, also has separate 5v boost regulator for powering peripheral devicesTwo 20-pin headers for accessing all available I/O pins 6 Grove-style sockets for easy connections to sensors and devices This is the newest version (v0.5) that was released in March 2017. The memory card socket, RTC, and solar charging features make it very easy to use this board for data logging and low-power operation. But it can also be used by itself, or with a wide variety of devices and accessories. It can be powered by a 3.7v lithium battery (not supplied) or through the microUSB port. Programming can be done through the microUSB port (cable not supplied) or via the FTDI header. You will need a CR1220 button cell lithium battery (not supplied) in order for the RTC to retain the time after the power has been removed. More information and tutorials for the board can be found on the EnviroDIY website.