Pins
Pins are used to communicate with your microcontroller, and can be configured to do different things, depending on your goal.
See picture below for pin placement on an Arduino Uno board.
Arduino
Digital
All the digital pins (PWM) can be used for input and output for general purpose. The TX and RX pin should however be avoided since these pins are used to handle TTL serial data.
Analog
The analog pins support 10-bit analog-to-digital conversion but can also be used as digital pins. Here analog pin 0 would be digital pin 14 through analog pin 5 being digital pin 19.
Power
- Vin (sometimes labelled as 9V) is the input voltage of the Arduino board when it’s using an external power source.
- 5V pin is the regulated power pin that is the normal voltage the power supply of the board would provide. This pin provides 5V to parts that would require power through the board.
- 3V3 is a 3.3-volt supply generated by the on board FTDI chip.
- GND is ground pins.
Other pins
- AREF is the reference voltage for the analog inputs.
- Reset bring this line to LOW to reset the microcontroller. This is typically used to add a reset button to shields which block the one on the board.
Raspberry Pi
3V3
The 3V3 pin is a 3.3V power supply pin. This is used for connecting hardware to a 3.3 power supply.
5V
The 5V pin is a 5-volt power supply pin. This pin is used for connecting hardware to a 5V power supply.
GPIO
The GPIO (General Purpose Input Output) pins are the most general and accessible pins. The pins are digital which means they have two states; on and off.
Ground
The ground pins is as you might have guessed, the grounds on the board. Other pins Some of the pins also have weird codes below them, which indicates different things. For further reading on these pins, you can read this article.