Billboard Bot

I've been experimenting with a MAX7219 LED matrix display on Raspberry Pi and Arduino and decided to combine a message board with a line-following car to build a billboard bot. This project is just a proof-of-concept and more complex scenarios could be derived from it. For now, it just follows a line until it sees a stop sign denoted by a thick perpendicular black line and delivers a pre-programmed message.

Above photo shows an ultrasonic sensor mounted on the bumper but that is not needed/used on this use case.

This Instructable is a remix of:

1) Line-following robot (I'm the author of this Instructure)

2) MAX7219 LED Matrix

Step 1: Parts

For this project, you'll need:

1) Line-following car similar to https://www.instructables.com/id/Yet-Another-Line-F...

2) Max7219 4 in 1 module. You could buy four 8x8 LED matrix modules and interconnect them together but I think buying 4 in 1 module is better.

Step 2: Putting Them Together

I used cardboard and glue gun to build a stand for the LED module as shown on the video.

Connect the 5 wires from the LED module to the Arduino pins. (The line-following car is already consuming most of the digital ports so I'm using analog ports as digital output instead.)

LED module-> Arduino
VCC->5V
GND->GND
DIN->A0;            
CLK->A2
CS->A1

Step 3: Coding

Attached is the Arduino code I used to produce the video.

To change the scrolltext, simply change the line #17 to whatever you want to display.

 const unsigned char scrollText[] PROGMEM = {"  Happy New Year!   \0"};

That's it. Happy New Year!