Pin/Screw Terminal Description

	Description
+	This screw terminal position is connected to the positive leg of the supply.
-	This screw terminal position is connected to the ground leg of the supply.
5V	This is a 5V output from the voltage regulator.
3V3	This is the output of the 3.3V voltage regulator.
GND	Board ground pin.
A0-A7	Analog input pins.
D2-D13	Digital I/O pins.
RX	Primarily used as a UART RX pin, can also be used as a digital GPIO.
TX	Primarily used as a UART TX pin, can also be used as a digital GPIO.
SDA	Primarily used as a data pin for I 2C, can also be used as a digital GPIO.
SCL	Primarily used as a clock pin for I 2C, can also be used as a digital GPIO.
NO	Normally Open pin for the relay.
COM	Common pin for the relay.
NC	Normally Closed pin for the relay.
RLY Extension	JST XH male connector. Can be used for more relay control pins or digital I/O.