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A crystal rectifier matrix may be a 2-dimensional array of LEDs that may be wont to show symbols, characters or maybe pictures. supported the orientation of the LEDs within the matrix, there may be 2 styles of crystal rectifier matrices. They are Common Row Anode and customary Row Cathode.

IC MAX 7219:

Max 7219 IC

MAX 7219 may be a common cathode show driver with serial input and parallel output. it’s wont to interface microprocessors and microcontrollers with sixty-four individual diodes (8 x eight LED matrix as an example has sixty-four LEDs), seven section diode displays up to eight digits or bars chart displays.

The eight x eight diode matrix is connected to the goop 7219 as shown within the circuit diagram and also the information input is received from the Arduino board to the goop 7219. The diode matrix is often driven in 2 ways that. area unit they’re parallel (where every row or column are sent with parallel information) associated serial (where the info is distributed serially and an IC is employed to convert this serial data into parallel data).

LED Matrix:

Matrix Dot Display

In case of common row anode sort LED matrix, this sources (high or positive voltage) are given to the rows A-D and therefore the current sinks (low or negative voltage or ground) are has given to the columns 1-4.

An eight x eight LED matrix show is employed during this project to show the data. LED matrices are accessible in several designs like single color, dual color, multi-color or RGB LED matrix. they’re additionally accessible in several dimensions like five x seven, 8 x 8, 16 x 16, thirty-two x thirty-two, etc. supported the arrangement of the LEDs within the matrix, AN LED matrix is often either common row anode or common row cathode.

Arduino LED Matrix Interface:

One pin provides the clock signal to the LED show driver IC (MAX 7219) whereas another pin is employed to transmit the serial information to the IC for displaying on the LED matrix. The corresponding pins should be fittingly mentioned in the program.

In case of common row cathode kind LED matrix, the present sources (high or positive voltage) area unit given to the columns 1-4 and therefore the current sinks (low or negative voltage or ground) area unit given to the rows A-D.

The LED matrix utilized in this project could be a common row cathode kind LED matrix. whereas developing the project, the sort of LED matrix should be renowned and therefore the program should be written consequently.

Required Componentes:

  • Arduino UNO         [Purchase Links]         Ali-Express      Amazon
  • MAX7219 IC Board                                     Ali-Express      Amazon  
  • 8×8 LED Matrix                                           Ali-Express      Amazon
  • HC-05 Bluetooth Module                            Ali-Express      Amazon
  • Android Phone with App installed                 

Circuit Diagram:

The second circuit within the Arduino 8×8 crystal rectifier Matrix Interface series is predicated on Bluetooth Communication and humanoid Phone. during this project, we’ve interface Arduino with Associate in Nursing humanoid phone victimization Bluetooth Communication and therefore the 8×8 crystal rectifier Matrix connected to Arduino through MAX7219 is controlled through a zealous application on the humanoid Phone.

7219 IC Control Mobile App

We have already seen within the previous project as however the 8×8 crystal rectifier Matrix and therefore the MAX7219 IC square measure connected. So, I’ll skip that a part of the association and proceed with however MAX7219 IC is interfaced with Arduino. Since the communication between Arduino and MAX7219 is predicated on SPI Communication Protocol, all we want is 3 pins from Arduino (Data, Clock and Chip Select). The CS, CLK and DIN pins of the MAX7219 IC Board square measure connected to pins ten, eleven and twelve of the Arduino.

As we tend to square measure victimization the Bluetooth association between Arduino and humanoid device, the RX and American state pins of the HC-05 Bluetooth Module square measure connected to American state and RX pins of the Arduino (Pins 1 and 0).

Controlling Android App:


  • The app has 8×8 squares (each appreciates one diode on the 8×8 diode Matrix), a button and a Disconnect button.
  • Touching a selected sq. can activate the actual diode within the 8×8 diode Matrix.
  • The color of the sq. can flip Red, as a sign that the diode is turned ON.
  • Touching the sq. another time can close up the corresponding diode and also the color of the sq. can revert back to gray.
  • A button is given at very cheap, victimization that you’ll reset the 8×8 diode Matrix i.e. all the LEDs are turned OFF.
  • The disconnect button can get disconnected from the Bluetooth.