Description
The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x). It has more or less the same functionality of the Arduino Duemilanove but in a different package. It lacks only a DC power jack and works with a Mini-B USB cable instead of a standard one. The Nano was designed and is being produced by Gravitech.
Specifications
| Microcontroller | ATmega328 |
| Operating Voltage (logic level) | 5 V |
| Input Voltage (recommended) | 7-12 V |
| Input Voltage (limits) | 6-20 V |
| Digital I/O Pins | 14 (of which 6 provide PWM output) |
| Analog Input Pins | 8 |
| DC Current per I/O Pin | 40 mA |
| Flash Memory | 16 KB (ATmega168) or 32 KB (ATmega328) of which 2 KB used by bootloader |
| SRAM | 1 KB (ATmega168) or 2 KB (ATmega328) |
| EEPROM | 512 bytes (ATmega168) or 1 KB (ATmega328) |
| Clock Speed | 16 MHz |
| Dimensions | 0.73 x 1.70' (18 x 45 mm) |
Power
The Arduino Nano can be powered via the Mini-B USB connection, 6-20 V unregulated external power supply (pin 30), or 5 V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.
Memory
- The ATmega168 has 16 KB of flash memory for storing code (of which 2 KB is used for the bootloader), 1 KB of SRAM and 512 bytes of EEPROM
- The ATmega328 has 32 KB of flash memory for storing code, (also with 2 KB used for the bootloader), 2 KB of SRAM and 1 KB of EEPROM.
Input and Output
Each of the 14 digital pins on the Nano can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 V.
Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor (disconnected by default) of 20-50 kOhms.
Communication
The Arduino Nano has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers.
The ATmega168 and ATmega328 provide UART TTL (5V) serial communication, which is available on digital pins 0 (RX) and 1 (TX). An FTDI FT232RL on the board channels this serial communication over USB and the FTDI drivers (included with the Arduino software) provide a virtual com port to software on the computer.
The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the Arduino board. The RX and TX LEDs on the board will flash when data is being transmitted via the FTDI chip and USB connection to the computer (but not for serial communication on pins 0 and 1).
A SoftwareSerial library allows for serial communication on any of the Nano's digital pins.
Programming
The Arduino Nano can be programmed with the Arduino software (download).
The ATmega168 or ATmega328 on the Arduino Nano comes with a bootloader that allows you to upload new code to it without the use of an external hardware programmer. It communicates using the original STK500 protocol (reference, C header files).
You can also bypass the bootloader and program the microcontroller through the ICSP (In-Circuit Serial Programming) header using Arduino ISP or similar; see these instructions for details.
Automatic (Software) Reset
Rather than requiring a physical press of the reset button before an upload, the Arduino Nano is designed in a way that allows it to be reset by software running on a connected computer.
One of the hardware flow control lines (DTR) of theFT232RL is connected to the reset line of the ATmega168 or ATmega328 via a 100 nF capacitor. When this line is asserted (taken low), the reset line drops long enough to reset the chip.
The Arduino software uses this capability to allow you to upload code by simply pressing the upload button in the Arduino environment. This means that the bootloader can have a shorter timeout, as the lowering of DTR can be well-coordinated with the start of the upload.
