![make the cut 4 1 0 serial port make the cut 4 1 0 serial port](https://i.ytimg.com/vi/P7Y8WI8vpSM/maxresdefault.jpg)
Typically used to add a reset button to shields which block the one on the board. Bring this line LOW to reset the microcontroller. There are a couple of other pins on the board: Support I2C (TWI) communication using the Wire library (documentation on the Wiring website). Additionally, some pins have specialized functionality: Analog pins 6 and 7 cannot be used as digital pins. By default they measure from ground to 5 volts, though is it possible to change the upper end of their range using the analogReference() function. The Nano has 8 analog inputs, each of which provide 10 bits of resolution (i.e. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off. There is a built-in LED connected to digital pin 13. These pins support SPI communication, which, although provided by the underlying hardware, is not currently included in the Arduino language. Provide 8-bit PWM output with the analogWrite() function. See the attachInterrupt() function for details. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. These pins are connected to the corresponding pins of the FTDI USB-to-TTL Serial chip. Used to receive (RX) and transmit (TX) TTL serial data. In addition, some pins have specialized functions: 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. Each of the 14 digital pins on the Nano can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions.