Netduino is equipped with a varied set of Input and Output (I/O) ports that can be accessed from your application to read sensors, listen to button presses, light LEDs, drive motors, communicate with other systems, and lots more.

Netduino IO ports are divided into two categories; Digital and Analog.

N3 Pinout Diagram
N3 Pinout Diagram

General Purpose Input/Output (GPIO) Ports


The Digital ports can be set to be high (powered at 3.3v), or low (grounded at 0v) which correspond to digital 1 and 0, respectively. Additionally, they have built-in support for a host of different types of common digital communication protocols:

I2C is normally used to connect low speed devices over short distances. Compare this to the main characteristics of SPI and Serial communications:

Protocol Characteristics
I2C Two wires
Short distance
Low speed
SPI Minimum of two wires, often more
High speed
Serial Low speed
Used for communication between boards
Can be used to communicate with on board devices
Analog Ports

Analog ports can operate at a range of voltages between 0V and 3.3V, which is especially useful when reading analog sensors that supply their data as a voltage reading, rather than a digital signal.

Current Tolerance and Output
  • Maximum GPIO Current - The maximum current output is 25mA per pin.
  • Maximum MCU Output Current - The total maximum current output for all pins is 125mA.
  • Digital I/O - 3.3V nominal, but tolerant up to 5V input.
  • IOREF - 3.3V (for shield compatibility).

Onboard Button & LED

In addition to the Analog and Digital Headers, the Netduino has an LED and a Button built into it that you can access from code. See the Onboard Button and LED guide for more information.

SD Card

Netduino 2 and 3 can access up to 2GB of storage on a Micro SD Card. Some models have an SD card slot on the board, but models that don’t have one built in can use an SD Card Shield. See the SD Card File IO guide for ore information.


These docs are open source. If you find an issue, please file a bug, or send us a pull request. And if you want to contribute, we'd love that too!