3.9. Pin assignments

The table below lists the most important pin assignments for the ATmega32U4 on the Balboa 32U4 control board. This table is helpful if you want to add your own electronics to Balboa 32U4, write your own low-level code for interfacing with the hardware, or just want to understand better how Balboa32U4 works. Each row represents a physical pin on the ATmega32U4.

The “ATmega32U4 pin name” column shows the official name of the pin according to the ATmega32U4 datasheet.

The “Arduino pin names” column lists the names provided by the Arduino environment for the pin. These names can generally be used as arguments to any function that takes a pin number. However, there are some exceptions. For example, passing the number 4 to analogRead actually reads pin A4, not pin 4. Also, due to hardware limitations, some functions only work on a limited set of pins.

The “Balboa 32U4 functions” column documents what the pin is used for on the Balboa 32U4 control board. Many pins can serve multiple purposes concurrently by switching modes. For example, PB0 can read the state of button C when it is an input, and it can control the red LED and serve as an LCD data line when it is an output.

The “Note/alternate functions” column documents other features of the pin, although some of those features might be impractical to use.