Bill of Materials

This implementation of ping pong uses:

Setting Up the Arduino and Pots

Begin by setting up the circuit using only the pots and the Arduino.
The two pots should be placed on opposite sides of a breadboard; each one
should face “outward”, i.e., away from the center of the board.

For each of the two pots:

The resulting circuit looks like this:

Connecting Just the Pots

For this setup, a short sketch, shown in code can
be used to measure the full range of motion of each pot and set the limits

Adding the LED Matrix

The circuit board on which the MAX7219 display driver chip is mounted comes with
header pins which need to be soldered in place. (Both straight and bent header pins
come with the PC board, along different configurations,
including chained several matrices together.

This project just uses the straight pins as shown below:

Header pins before soldering Header pins inserted

Notice that the pins are inserted into the side with the DIN connector. This is where the
data coming from the Arduino is fed into the matrix.

Now insert the LED matrix into the circuit board. Be sure to line up pin
1 on the back of the LED matrix with pin 1 on the front of the circuit board.

Pin 1 on the back of the LED matrix Pin 1 on the circuit board

Now the LED matrix plus its companion PC board should be ready to insert into your breadboard.
Insert this combo anywhere, as long as all 5 header pins are inserted into different columns of
the breadboard. (Notice that the matrix+PC-board combo will be a little floppy because it
is actually larger than the PC board.)

Now make 5 connections from the PC board to the Arduino circuit. These 5 connections will
power the PC board and LED matrix, and will also set up a serial communications interface
between the PC board and the Arduino. This interface differs from the “simple” Rx/Tx lines
that are used for the Arduino’s Serial Console, because it is synchronous: data is sent/received
at precise times that are determined by a separate clock signal. This interface is fast and
efficient for devices like the matrix which (because it has a time-regular need for data) benefits
from an interface which is simpler and faster than the asynchronous interface used with the
Serial Console.

With that said, here are the connections:

To power the LED matrix, you might need more power than the Arduino can supply. In that
case, connect the + and - terminals of an external battery or power supply to the
red and black rails of the breadboard.