Lesson 1: Part 4: Controlling GPIO - External Output - LED Control

To control external LED, the circuit would be as below:

PC9 With External LED

PC9 -> Orange Wire -> 30 Ohm Resistor* -> LED -> Black Wire -> GND

*Note: Use 30 Ohm resistor, image shown is NOT 30 Ohm resistor
*The resistor is use to limit the current, thus it is OK to put put before or after the LED.


As the voltage line at PC9 is only 3.3V, the LED may not achieve maximum brightness. But this example is good enough to demonstrate how we can connect to external device(LED).

A transistor(2N3904) can be use in order to increase control voltage to 5V.