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The Displayduino microcontroller is the main controller for any MondoMatrix modular system.  However, Displayduino controllers can be used on their own to control up to 32 inputs or outputs.  Displayduino works exactly like Arduino and uses the Arduino Programming Language.  This means that programming the Displayduino microcontroller is the same as programming an Arduino Microcontroller.  The difference between Arduino and Displayduino controllers is that you can plug-in MondoMatrix expansion boards to a Displayduino and grow your projects to thousands of lights, motors, sounds or any other output device.

Displayduino controllers have many features that make them easy to use.  First, there is no soldering required.  The boards come with screw terminals allowing users to tightly affix wires to the board using a small screw driver.  There are also pin-strip header ‘ports’ just as with Arduino so that you can use the ports if you prefer.  This design also makes it easy for users to develop their own mountable shields.  Another great feature is that you can remove the Displayduino chip if it becomes damaged.  You can get another chip and boatload the chip (flash the chip) to replace damaged chips drastically reducing the cost of recovery if you burn out a chip while experimenting.  Being able to remove the chip also means that you can program the chip and remove it to install it on other boards or in something small or portable such as a wearable project.

Introduction Video:


  • Board is 4.8 by 2.25 inches
  • Holes on the corners of a 4.4 by 1.85 inch rectangle (same diameter holes as other boards)

Processor specs:

  • ATMEGA644P processor at 20 MHz
  • 64KB of Flash code space
  • 2KB of EEPROM storage space
  • 4KB of RAM

2 asynchronous serial ports (port 0 for USB communication, port 1 for RS485 communication with other MondoMatrix boards)

  • 1 SPI serial port
  • 1 I2C serial port
  • 8 Analog input channels
  • 32 digital I/O lines (8 are also Analog inputs)
  • 6 PWM outputs

On-board voltage regulator, input range 7-12V DC, approx. 200 mA under normal circumstances 5V output available, suggest drawing no more than 400 mA, less if powered over USB Board (can switch between on-board power and USB power)

4 on board LEDs:

  • Power (”P”)
  • Transmit (”T”)
  • Receive (”R”)
  • LED connected to Digital 0 line, for debugging (”L”)

On-board RS485 transceiver chip for connection to other MondoMatrix boards using MatrixNet protocol

Digital 22 output hard-wired to RS485 transceiver for data direction control – if using RS485 (it is unavailable for other use).

Sample Arduino Code

// Turns on one of the LEDs on the board for one second, then off for one second, repeatedly.

int ledPin =  0;    // LED connected to digital pin 0
// The setup() method runs once, when the sketch starts
void setup()   {
  // initialize the digital pin as an output:
  pinMode(ledPin, OUTPUT);

// the loop() method runs over and over again,
// as long as the Arduino has power
void loop()
  digitalWrite(ledPin, HIGH);   // set the LED on
  delay(1000);                  // wait for a second
  digitalWrite(ledPin, LOW);    // set the LED off
  delay(1000);                  // wait for a second

Source Code (NEW May 22, 2011!)

The source code and hardware files (schematic and PCB layout) for the Displayduino are available here.

RS485 Information


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