The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328. It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard one.
Microcontroller Atmel ATmega328
Operating voltage 5V
Input voltage range nom. 7 to 12V
Maximum supply voltage 6 to 20V
Digital I/O pins 22(of which 6 provide PWM output)
Analog input pins 8
DC Current per I/O pin 40 mA
Flash memory 32 KB of which 2 KB is used by bootloader
SRAM 2 KB
EEPROM 1 KB
Clock speed 16 MHz
USB Connector type Mini B male
NOTE: We have updated the NANO board with a fresh bootloader. Boards sold from us from January 2018 onwards include this new bootloader, while boards manufactured before that date have the old bootloader.
First, make sure you have the Arduino AVR Core 1.16.21 or later looking at the Board Manager. Then, to program the NEW Arduino NANO boards you need to chose Processor > "ATmega328P". To program old boards you need to choose Processor > "ATmega328P (Old Bootloader)".
If you get an error while uploading or you are not sure which bootloader you have, try each type of processor 328P until your board gets properly programmed.