Now, we’ll be adding our 1k Ohm resistor to the circuit. This resistor is a component that limits the current between the mp3 module and the microcontroller so it can talk to it properly. When adding the resistor, make sure the left leg of the resistor is connected to the same column as the RX pin of the mp3 module. Use the following pinout diagram as reference:
The right leg should be connected to a column that is currently unoccupied.
Here is the breadboard wiring diagram for this step: