Arduino Uno + MAX7219 8x8 LED Matrix via SPI, using LedControl Library

We can add LedControl Library to Arduino IDE, to control 8*8 LED Matrix with MAX7219 via SPI. LedControl is a library for the MAX7219 and the MAX7221 Led display driver.
(ref: http://wayoda.github.io/LedControl/)

Open the File > Examples > LedControl > LCDemoMatrix

LCDemoMatrix.ino

//We always have to include the library
#include "LedControl.h"

/*
 Now we need a LedControl to work with.
 ***** These pin numbers will probably not work with your hardware *****
 pin 12 is connected to the DataIn 
 pin 11 is connected to the CLK 
 pin 10 is connected to LOAD 
 We have only a single MAX72XX.
 */
LedControl lc=LedControl(12,11,10,1);

/* we always wait a bit between updates of the display */
unsigned long delaytime=100;

void setup() {
  /*
   The MAX72XX is in power-saving mode on startup,
   we have to do a wakeup call
   */
  lc.shutdown(0,false);
  /* Set the brightness to a medium values */
  lc.setIntensity(0,8);
  /* and clear the display */
  lc.clearDisplay(0);
}

/*
 This method will display the characters for the
 word "Arduino" one after the other on the matrix. 
 (you need at least 5x7 leds to see the whole chars)
 */
void writeArduinoOnMatrix() {
  /* here is the data for the characters */
  byte a[5]={B01111110,B10001000,B10001000,B10001000,B01111110};
  byte r[5]={B00111110,B00010000,B00100000,B00100000,B00010000};
  byte d[5]={B00011100,B00100010,B00100010,B00010010,B11111110};
  byte u[5]={B00111100,B00000010,B00000010,B00000100,B00111110};
  byte i[5]={B00000000,B00100010,B10111110,B00000010,B00000000};
  byte n[5]={B00111110,B00010000,B00100000,B00100000,B00011110};
  byte o[5]={B00011100,B00100010,B00100010,B00100010,B00011100};

  /* now display them one by one with a small delay */
  lc.setRow(0,0,a[0]);
  lc.setRow(0,1,a[1]);
  lc.setRow(0,2,a[2]);
  lc.setRow(0,3,a[3]);
  lc.setRow(0,4,a[4]);
  delay(delaytime);
  lc.setRow(0,0,r[0]);
  lc.setRow(0,1,r[1]);
  lc.setRow(0,2,r[2]);
  lc.setRow(0,3,r[3]);
  lc.setRow(0,4,r[4]);
  delay(delaytime);
  lc.setRow(0,0,d[0]);
  lc.setRow(0,1,d[1]);
  lc.setRow(0,2,d[2]);
  lc.setRow(0,3,d[3]);
  lc.setRow(0,4,d[4]);
  delay(delaytime);
  lc.setRow(0,0,u[0]);
  lc.setRow(0,1,u[1]);
  lc.setRow(0,2,u[2]);
  lc.setRow(0,3,u[3]);
  lc.setRow(0,4,u[4]);
  delay(delaytime);
  lc.setRow(0,0,i[0]);
  lc.setRow(0,1,i[1]);
  lc.setRow(0,2,i[2]);
  lc.setRow(0,3,i[3]);
  lc.setRow(0,4,i[4]);
  delay(delaytime);
  lc.setRow(0,0,n[0]);
  lc.setRow(0,1,n[1]);
  lc.setRow(0,2,n[2]);
  lc.setRow(0,3,n[3]);
  lc.setRow(0,4,n[4]);
  delay(delaytime);
  lc.setRow(0,0,o[0]);
  lc.setRow(0,1,o[1]);
  lc.setRow(0,2,o[2]);
  lc.setRow(0,3,o[3]);
  lc.setRow(0,4,o[4]);
  delay(delaytime);
  lc.setRow(0,0,0);
  lc.setRow(0,1,0);
  lc.setRow(0,2,0);
  lc.setRow(0,3,0);
  lc.setRow(0,4,0);
  delay(delaytime);
}

/*
  This function lights up a some Leds in a row.
 The pattern will be repeated on every row.
 The pattern will blink along with the row-number.
 row number 4 (index==3) will blink 4 times etc.
 */
void rows() {
  for(int row=0;row<8;row++) {
    delay(delaytime);
    lc.setRow(0,row,B10100000);
    delay(delaytime);
    lc.setRow(0,row,(byte)0);
    for(int i=0;i<row;i++) {
      delay(delaytime);
      lc.setRow(0,row,B10100000);
      delay(delaytime);
      lc.setRow(0,row,(byte)0);
    }
  }
}

/*
  This function lights up a some Leds in a column.
 The pattern will be repeated on every column.
 The pattern will blink along with the column-number.
 column number 4 (index==3) will blink 4 times etc.
 */
void columns() {
  for(int col=0;col<8;col++) {
    delay(delaytime);
    lc.setColumn(0,col,B10100000);
    delay(delaytime);
    lc.setColumn(0,col,(byte)0);
    for(int i=0;i<col;i++) {
      delay(delaytime);
      lc.setColumn(0,col,B10100000);
      delay(delaytime);
      lc.setColumn(0,col,(byte)0);
    }
  }
}

/* 
 This function will light up every Led on the matrix.
 The led will blink along with the row-number.
 row number 4 (index==3) will blink 4 times etc.
 */
void single() {
  for(int row=0;row<8;row++) {
    for(int col=0;col<8;col++) {
      delay(delaytime);
      lc.setLed(0,row,col,true);
      delay(delaytime);
      for(int i=0;i<col;i++) {
        lc.setLed(0,row,col,false);
        delay(delaytime);
        lc.setLed(0,row,col,true);
        delay(delaytime);
      }
    }
  }
}

void loop() { 
  writeArduinoOnMatrix();
  rows();
  columns();
  single();
}

Connect MAX7219 8x8 LED Matrix to Arduino Uno as stated in the example:
- pin 12 is connected to the DataIn
- pin 11 is connected to the CLK
- pin 10 is connected to LOAD (it's cs marked on my sample)
- +5V to VCC
- GND to GND

Run.

Check the video:

Raspberry Pi control Arduino + 8x8 LED Matrix, using Java/JavaFX/jSSC

Actually, it's same as last post "Java/JavaFX/jSSC control Arduino + 8x8 LED Matrix", but run on Raspberry Pi 2/Raspbian remotely, instead of run on Windows 10/NetBeans locally.

---

Host development platform:
OS: Windows 10
IDE: NetBeans IDE 8.0.2
Programming Language: Java + JavaFX + jSSC

Target platform:
Raspberry Pi 2
OS: Raspbian
IP: 192.168.1.112
Both Host development platform and Target platform in the same Network.
(How to set Remote Java SE Platform to deploy on Raspberry Pi, refer to the video in the post "Java + JavaFX + jSSC run on Raspberry Pi, control Arduino Uno")

remark: due to something wrong on my Raspberry Pi 2 cannot detect monitor correctly, I have to edit /boot/config.txt to set framebuffer_width and framebuffer_height to 500x400. So the screen output may be differency to you.

Arduino Side:
Board: Arduino Uno + 8x8 LED Matrix
Connected to Raspberry Pi 2 with USB.

---

Arduino Side:

Arduino code and connection between Arduino Uno and 8x8 LED Matrix, refer last post.

Java/JavaFX/jSSC code, program on Windows 10/NetBeans, run on Raspberry Pi 2:
(Basically same as last post, with moving btnExit to vBoxMatrix, such that user can exit the program in raspberry Pi UI.

    package javafx_matrix;

import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.control.RadioButton;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import jssc.SerialPort;
import static jssc.SerialPort.MASK_RXCHAR;
import jssc.SerialPortEvent;
import jssc.SerialPortException;
import jssc.SerialPortList;

public class JavaFX_Matrix extends Application {
    
    final private int NUM_X = 8;
    final private int NUM_Y = 8;
    
    SerialPort arduinoPort = null;
    ObservableList<String> portList;

    @Override
    public void start(Stage primaryStage) {
        
        //ComboBox for port selection
        detectPort();
        final ComboBox comboBoxPorts = new ComboBox(portList);
        comboBoxPorts.valueProperty()
                .addListener(new ChangeListener<String>() {

            @Override
            public void changed(ObservableValue<? extends String> observable, 
                    String oldValue, String newValue) {

                System.out.println(newValue);
                disconnectArduino();
                connectArduino(newValue);
            }

        });
        
        //
        
        final Label label = new Label("arduino-er.blogspot.com");
        label.setFont(Font.font("Arial", 24));
        
        Button btnExit = new Button("Exit");
        btnExit.setOnAction((ActionEvent event) -> {
            Platform.exit();
        });

        VBox vBoxInfo = new VBox();
        //vBoxInfo.getChildren().addAll(label, btnExit);
        vBoxInfo.getChildren().add(label);
        
        //Matrix of RadioButton
        VBox vBoxMatrix = new VBox();
        vBoxMatrix.setPadding(new Insets(10, 10, 10, 10));

        for(int y=0; y<NUM_Y; y++){
            
            HBox box = new HBox();
            for(int x=0; x<NUM_X; x++){
                MatrixButton btn = new MatrixButton(x, y);
                box.getChildren().add(btn);
            }
            vBoxMatrix.getChildren().add(box);
            
        }
        vBoxMatrix.getChildren().add(btnExit);
        
        vBoxMatrix.widthProperty().addListener(new ChangeListener<Number>(){

            @Override
            public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
                comboBoxPorts.setPrefWidth((double)newValue);
                btnExit.setPrefWidth((double)newValue);
            }
        });

        BorderPane borderPane = new BorderPane();
        borderPane.setTop(comboBoxPorts);
        borderPane.setCenter(vBoxMatrix);
        borderPane.setBottom(vBoxInfo);

        Scene scene = new Scene(borderPane, 300, 250);

        primaryStage.setTitle("Arduino-er");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
    
    @Override
    public void stop() throws Exception {
        disconnectArduino();
        super.stop();
    }
    
    private void detectPort(){
         
        portList = FXCollections.observableArrayList();
 
        String[] serialPortNames = SerialPortList.getPortNames();
        for(String name: serialPortNames){
            System.out.println(name);
            portList.add(name);
        }
    }
    
    public boolean connectArduino(String port){
        
        System.out.println("connectArduino");
        
        boolean success = false;
        SerialPort serialPort = new SerialPort(port);
        try {
            serialPort.openPort();
            serialPort.setParams(
                    SerialPort.BAUDRATE_9600,
                    SerialPort.DATABITS_8,
                    SerialPort.STOPBITS_1,
                    SerialPort.PARITY_NONE);
            serialPort.setEventsMask(MASK_RXCHAR);
            serialPort.addEventListener((SerialPortEvent serialPortEvent) -> {
                if(serialPortEvent.isRXCHAR()){            
                    //receive something for debug
                    try {
                        String st = serialPort.readString(serialPortEvent
                                .getEventValue());
                        System.out.println(st);
                        
                    } catch (SerialPortException ex) {
                        Logger.getLogger(JavaFX_Matrix.class.getName())
                                .log(Level.SEVERE, null, ex);
                    }
                    
                }
            });
            
            arduinoPort = serialPort;
            
            //Send dummy to clear buffer
            try {
                Thread.sleep(2000);
            } catch (InterruptedException ex) {
                Logger.getLogger(JavaFX_Matrix.class.getName())
                        .log(Level.SEVERE, null, ex);
            }
            sendDotArduino(0, 0, false);
            
            success = true;
        } catch (SerialPortException ex) {
            Logger.getLogger(JavaFX_Matrix.class.getName())
                    .log(Level.SEVERE, null, ex);
            System.out.println("SerialPortException: " + ex.toString());
        }

        return success;
    }
    
    public void disconnectArduino(){
        
        System.out.println("disconnectArduino()");
        if(arduinoPort != null){
            try {
                arduinoPort.removeEventListener();
                
                if(arduinoPort.isOpened()){
                    arduinoPort.closePort();
                }
                
                arduinoPort = null;
            } catch (SerialPortException ex) {
                Logger.getLogger(JavaFX_Matrix.class.getName())
                        .log(Level.SEVERE, null, ex);
            }
        }
    }
    
    public void sendDotArduino(int x, int y, boolean s){
        final byte SYNC_WORD = (byte)0xFF;
        if(arduinoPort != null){
            byte[] buffer = new byte[]{
                SYNC_WORD,
                (byte)x, 
                (byte)y, 
                (byte)(s ? 1 : 0)
            };

            try {
                arduinoPort.writeBytes(buffer);
            } catch (SerialPortException ex) {
                Logger.getLogger(JavaFX_Matrix.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

    class MatrixButton extends RadioButton {

        public MatrixButton(int x, int y) {
            
            setOnAction((ActionEvent event) -> {
                
                RadioButton src = (RadioButton) event.getSource();    
                JavaFX_Matrix.this.sendDotArduino(x, y, src.isSelected());
                
            });
        }
    }

}

Java/JavaFX/jSSC control Arduino + 8x8 LED Matrix

It's a example to control Arduino Uno + 8x8 LED Matrix, from USB connected PC running Windows 10, programmed with Java + JavaFX + jSSC(java-simple-serial-connector).

Arduino Side:

Connection between Arduino Uno and 8x8 LED:

UnoSerialInMatrix.ino

// 2-dimensional array of row pin numbers:
const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

int incomingByte = 0;

void setup() {
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  clearScr();

  Serial.begin(9600);
  
}

void loop() {
  if (Serial.available() > 0) {
    incomingByte = Serial.read();
    doProcess(incomingByte);
  }
  
  // draw the screen:
  refreshScreen();

}

const int SYNC_WORD = 0xFF;
const int ST_0_IDLE = 0;
const int ST_1_WAITX = 1;
const int ST_2_WAITY = 2;
const int ST_3_WAITB = 3;
int prc_State = ST_0_IDLE;
int dotX, dotY, dotB;

void doProcess(int b){
  switch(prc_State){
    case ST_0_IDLE:
        if(b == SYNC_WORD){
          prc_State = ST_1_WAITX;
          Serial.println("1");
        }
        break;
    case ST_1_WAITX:
        dotX = b;
        prc_State = ST_2_WAITY;
        Serial.println("2");
        break;
    case ST_2_WAITY:
        dotY = b;
        prc_State = ST_3_WAITB;
        Serial.println("3");
        break;
    case ST_3_WAITB:

        if(b == 1){
          pixels[dotY][dotX] = LOW;
        }else{
          pixels[dotY][dotX] = HIGH;
        }

        prc_State = ST_0_IDLE;
        Serial.println("0");
        break;
    default:
        prc_State = ST_0_IDLE;
  }
}

void clearScr(){
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = HIGH;
    }
  }
}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}

PC Side:

Before start, you have to Prepare jSSC on your NetBeans project.

JavaFX_Matrix.java

package javafx_matrix;

import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ComboBox;
import javafx.scene.control.Label;
import javafx.scene.control.RadioButton;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import jssc.SerialPort;
import static jssc.SerialPort.MASK_RXCHAR;
import jssc.SerialPortEvent;
import jssc.SerialPortException;
import jssc.SerialPortList;

public class JavaFX_Matrix extends Application {
    
    final private int NUM_X = 8;
    final private int NUM_Y = 8;
    
    SerialPort arduinoPort = null;
    ObservableList<String> portList;

    @Override
    public void start(Stage primaryStage) {
        
        //ComboBox for port selection
        detectPort();
        final ComboBox comboBoxPorts = new ComboBox(portList);
        comboBoxPorts.valueProperty()
                .addListener(new ChangeListener<String>() {

            @Override
            public void changed(ObservableValue<? extends String> observable, 
                    String oldValue, String newValue) {

                System.out.println(newValue);
                disconnectArduino();
                connectArduino(newValue);
            }

        });
        
        //
        
        final Label label = new Label("arduino-er.blogspot.com");
        label.setFont(Font.font("Arial", 24));
        
        Button btnExit = new Button("Exit");
        btnExit.setOnAction((ActionEvent event) -> {
            Platform.exit();
        });

        VBox vBoxInfo = new VBox();
        vBoxInfo.getChildren().addAll(label, btnExit);
        
        //Matrix of RadioButton
        VBox vBoxMatrix = new VBox();
        vBoxMatrix.setPadding(new Insets(10, 10, 10, 10));

        for(int y=0; y<NUM_Y; y++){
            
            HBox box = new HBox();
            for(int x=0; x<NUM_X; x++){
                MatrixButton btn = new MatrixButton(x, y);
                box.getChildren().add(btn);
            }
            vBoxMatrix.getChildren().add(box);
            
        }
        
        vBoxMatrix.widthProperty().addListener(new ChangeListener<Number>(){

            @Override
            public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
                comboBoxPorts.setPrefWidth((double)newValue);
                btnExit.setPrefWidth((double)newValue);
            }
        });

        BorderPane borderPane = new BorderPane();
        borderPane.setTop(comboBoxPorts);
        borderPane.setCenter(vBoxMatrix);
        borderPane.setBottom(vBoxInfo);

        Scene scene = new Scene(borderPane, 300, 250);

        primaryStage.setTitle("Arduino-er");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
    
    @Override
    public void stop() throws Exception {
        disconnectArduino();
        super.stop();
    }
    
    private void detectPort(){
         
        portList = FXCollections.observableArrayList();
 
        String[] serialPortNames = SerialPortList.getPortNames();
        for(String name: serialPortNames){
            System.out.println(name);
            portList.add(name);
        }
    }
    
    public boolean connectArduino(String port){
        
        System.out.println("connectArduino");
        
        boolean success = false;
        SerialPort serialPort = new SerialPort(port);
        try {
            serialPort.openPort();
            serialPort.setParams(
                    SerialPort.BAUDRATE_9600,
                    SerialPort.DATABITS_8,
                    SerialPort.STOPBITS_1,
                    SerialPort.PARITY_NONE);
            serialPort.setEventsMask(MASK_RXCHAR);
            serialPort.addEventListener((SerialPortEvent serialPortEvent) -> {
                if(serialPortEvent.isRXCHAR()){            
                    //receive something for debug
                    try {
                        String st = serialPort.readString(serialPortEvent
                                .getEventValue());
                        System.out.println(st);
                        
                    } catch (SerialPortException ex) {
                        Logger.getLogger(JavaFX_Matrix.class.getName())
                                .log(Level.SEVERE, null, ex);
                    }
                    
                }
            });
            
            arduinoPort = serialPort;
            
            //Send dummy to clear buffer
            try {
                Thread.sleep(2000);
            } catch (InterruptedException ex) {
                Logger.getLogger(JavaFX_Matrix.class.getName())
                        .log(Level.SEVERE, null, ex);
            }
            sendDotArduino(0, 0, false);
            
            success = true;
        } catch (SerialPortException ex) {
            Logger.getLogger(JavaFX_Matrix.class.getName())
                    .log(Level.SEVERE, null, ex);
            System.out.println("SerialPortException: " + ex.toString());
        }

        return success;
    }
    
    public void disconnectArduino(){
        
        System.out.println("disconnectArduino()");
        if(arduinoPort != null){
            try {
                arduinoPort.removeEventListener();
                
                if(arduinoPort.isOpened()){
                    arduinoPort.closePort();
                }
                
                arduinoPort = null;
            } catch (SerialPortException ex) {
                Logger.getLogger(JavaFX_Matrix.class.getName())
                        .log(Level.SEVERE, null, ex);
            }
        }
    }
    
    public void sendDotArduino(int x, int y, boolean s){
        final byte SYNC_WORD = (byte)0xFF;
        if(arduinoPort != null){
            byte[] buffer = new byte[]{
                SYNC_WORD,
                (byte)x, 
                (byte)y, 
                (byte)(s ? 1 : 0)
            };

            try {
                arduinoPort.writeBytes(buffer);
            } catch (SerialPortException ex) {
                Logger.getLogger(JavaFX_Matrix.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

    class MatrixButton extends RadioButton {

        public MatrixButton(int x, int y) {
            
            setOnAction((ActionEvent event) -> {
                
                RadioButton src = (RadioButton) event.getSource();    
                JavaFX_Matrix.this.sendDotArduino(x, y, src.isSelected());
                
            });
        }
    }

}

Next:
- Raspberry Pi control Arduino + 8x8 LED Matrix, using Java/JavaFX/jSSC

---

- More example of Java/JavaFX/jSSC communicate with Arduino.

Beating Heart animation on 8x8 LED Matrix + Arduino Uno

This example run on Arduino uno, animate beating heart on 8x8 LED Matrix.

Example code:

// 2-dimensional array of row pin numbers:
const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

int count = 1000;

char str[] = "FABCDEDCBA";
int strLen = sizeof(str);
int ptrChar = 0;


typedef bool charMapType[8][8];

const charMapType charBlank = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType heart0 = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType heart1 = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType heart2 = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 1, 1, 0, 0, 1, 1, 0},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0}
};

const charMapType heart3 = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 1, 1, 0, 0, 1, 1, 0},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType heart4 = {
  {0, 1, 1, 0, 0, 1, 1, 0},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType *charMap[6] = {&heart0, &heart1, &heart2, &heart3, &heart4, &charBlank};

void setup() {
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  //setupScreen();
  setupChar();

}

void loop() {

  // draw the screen:
  refreshScreen();
  
  if(count-- == 0){
    count = 1000;
    setupChar();
  }

}

void setupChar(){
  char c = str[ptrChar];
  int offset = c - 'A';
  
  const charMapType *cMap = charMap[offset];
  //charMapType *cMap = &charDummy;
  
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      bool v = (*cMap)[x][y];
      
      if(v){
        pixels[x][y] = LOW;
      }else{
        pixels[x][y] = HIGH;
      }
    }
  }
  
  ptrChar++;
  if(ptrChar>=strLen-1){
    ptrChar = 0;
  }

}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}

Arduino Uno + SPI 8x8 LED Matrix, with MAX7219 LED driver

MAX7219 is a LED Driver from Maxim to drive either 64 individual Led's, or up to 8 digits of 7-segment displays. The drivers implement a SPI compatible slave interface that can be controlled from the Arduino using only 3 of the digital output pins. Know more about MAX7219, and MAX7221, refer to http://playground.arduino.cc/Main/MAX72XXHardware.

This example show how Arduino Uno work with DIY boeard of SPI 8x8 LED Matrix, with MAX7219 LED driver and 1088AS row cathode column anode 8x8 LED Matrix.


Visit http://playground.arduino.cc/LEDMatrix/Max7219, copy the sample sketch and un-comment your expected pattern to display.

//reference: http://playground.arduino.cc/LEDMatrix/Max7219

/* code for max 7219 from maxim, 
reduced and optimised for useing more then one 7219 in a row,
______________________________________

 Code History:
 --------------

The orginal code was written for the Wiring board by:
 * Nicholas Zambetti and Dave Mellis /Interaction Design Institute Ivrea /Dec 2004
 * http://www.potemkin.org/uploads/Wiring/MAX7219.txt

First modification by:
 * Marcus Hannerstig/  K3, malm� h�gskola /2006
 * http://www.xlab.se | http://arduino.berlios.de

This version is by:
 * tomek ness /FH-Potsdam / Feb 2007
 * http://design.fh-potsdam.de/ 

 * @acknowledgements: eric f. 

-----------------------------------

General notes: 


-if you are only using one max7219, then use the function maxSingle to control
 the little guy ---maxSingle(register (1-8), collum (0-255))

-if you are using more then one max7219, and they all should work the same, 
then use the function maxAll ---maxAll(register (1-8), collum (0-255))

-if you are using more than one max7219 and just want to change something
at one little guy, then use the function maxOne
---maxOne(Max you wane controll (1== the first one), register (1-8), 
collum (0-255))

/* During initiation, be sure to send every part to every max7219 and then
 upload it.
For example, if you have five max7219's, you have to send the scanLimit 5 times
before you load it-- other wise not every max7219 will get the data. the
function maxInUse  keeps track of this, just tell it how many max7219 you are
using.
*/

int dataIn = 2;
int load = 3;
int clock = 4;

int maxInUse = 4;    //change this variable to set how many MAX7219's you'll use

int e = 0;           // just a varialble

                     // define max7219 registers
byte max7219_reg_noop        = 0x00;
byte max7219_reg_digit0      = 0x01;
byte max7219_reg_digit1      = 0x02;
byte max7219_reg_digit2      = 0x03;
byte max7219_reg_digit3      = 0x04;
byte max7219_reg_digit4      = 0x05;
byte max7219_reg_digit5      = 0x06;
byte max7219_reg_digit6      = 0x07;
byte max7219_reg_digit7      = 0x08;
byte max7219_reg_decodeMode  = 0x09;
byte max7219_reg_intensity   = 0x0a;
byte max7219_reg_scanLimit   = 0x0b;
byte max7219_reg_shutdown    = 0x0c;
byte max7219_reg_displayTest = 0x0f;

void putByte(byte data) {
  byte i = 8;
  byte mask;
  while(i > 0) {
    mask = 0x01 << (i - 1);      // get bitmask
    digitalWrite( clock, LOW);   // tick
    if (data & mask){            // choose bit
      digitalWrite(dataIn, HIGH);// send 1
    }else{
      digitalWrite(dataIn, LOW); // send 0
    }
    digitalWrite(clock, HIGH);   // tock
    --i;                         // move to lesser bit
  }
}

void maxSingle( byte reg, byte col) {    
//maxSingle is the "easy"  function to use for a     //single max7219

  digitalWrite(load, LOW);       // begin     
  putByte(reg);                  // specify register
  putByte(col);//((data & 0x01) * 256) + data >> 1); // put data   
  digitalWrite(load, LOW);       // and load da shit
  digitalWrite(load,HIGH); 
}

void maxAll (byte reg, byte col) {    // initialize  all  MAX7219's in the system
  int c = 0;
  digitalWrite(load, LOW);  // begin     
  for ( c =1; c<= maxInUse; c++) {
  putByte(reg);  // specify register
  putByte(col);//((data & 0x01) * 256) + data >> 1); // put data
    }
  digitalWrite(load, LOW);
  digitalWrite(load,HIGH);
}

void maxOne(byte maxNr, byte reg, byte col) {    
//maxOne is for adressing different MAX7219's, 
//whilele having a couple of them cascaded

  int c = 0;
  digitalWrite(load, LOW);  // begin     

  for ( c = maxInUse; c > maxNr; c--) {
    putByte(0);    // means no operation
    putByte(0);    // means no operation
  }

  putByte(reg);  // specify register
  putByte(col);//((data & 0x01) * 256) + data >> 1); // put data 

  for ( c =maxNr-1; c >= 1; c--) {
    putByte(0);    // means no operation
    putByte(0);    // means no operation
  }

  digitalWrite(load, LOW); // and load da shit
  digitalWrite(load,HIGH); 
}


void setup () {


  pinMode(dataIn, OUTPUT);
  pinMode(clock,  OUTPUT);
  pinMode(load,   OUTPUT);

  //beginSerial(9600);
  digitalWrite(13, HIGH);  

//initiation of the max 7219
  maxAll(max7219_reg_scanLimit, 0x07);      
  maxAll(max7219_reg_decodeMode, 0x00);  // using an led matrix (not digits)
  maxAll(max7219_reg_shutdown, 0x01);    // not in shutdown mode
  maxAll(max7219_reg_displayTest, 0x00); // no display test
   for (e=1; e<=8; e++) {    // empty registers, turn all LEDs off 
    maxAll(e,0);
  }
  maxAll(max7219_reg_intensity, 0x0f & 0x0f);    // the first 0x0f is the value you can set
                                                  // range: 0x00 to 0x0f
}  

void loop () {


  //if you use just one MAX7219 it should look like this
  /*
   maxSingle(1,1);                       //  + - - - - - - -
   maxSingle(2,2);                       //  - + - - - - - -
   maxSingle(3,4);                       //  - - + - - - - -
   maxSingle(4,8);                       //  - - - + - - - -
   maxSingle(5,16);                      //  - - - - + - - -
   maxSingle(6,32);                      //  - - - - - + - -
   maxSingle(7,64);                      //  - - - - - - + -
   maxSingle(8,128);                     //  - - - - - - - +
  */

  //if you use more than one MAX7219, it should look like this
  
  maxAll(1,1);                       //  + - - - - - - -
  maxAll(2,3);                       //  + + - - - - - -
  maxAll(3,7);                       //  + + + - - - - -
  maxAll(4,15);                      //  + + + + - - - -
  maxAll(5,31);                      //  + + + + + - - -
  maxAll(6,63);                      //  + + + + + + - -
  maxAll(7,127);                     //  + + + + + + + -
  maxAll(8,255);                     //  + + + + + + + +
  
  //

  //if you use more then one max7219 the second one should look like this


  maxOne(2,1,1);                       //  + - - - - - - -
  maxOne(2,2,2);                       //  - + - - - - - -
  maxOne(2,3,4);                       //  - - + - - - - -
  maxOne(2,4,8);                       //  - - - + - - - -
  maxOne(2,5,16);                      //  - - - - + - - -
  maxOne(2,6,32);                      //  - - - - - + - -
  maxOne(2,7,64);                      //  - - - - - - + -
  maxOne(2,8,128);                     //  - - - - - - - +


  // 
  delay(2000);

}

For this example, connect the pins between the DIY board and Uno board.

• VCC - Uno 5V
• GND - Uno GND
• DIN - Uno 2
• CS - Uno 3
• CLK - Uno 4

Below video show soldering and assembling the DIY kit of SPI 8x8 LED Matrix board.


If you need to identify the pin 1 of the 1088AS 8x8 LED Matrix, refer to last post "How to identify pin 1 of 8x8 LED Matrix", part II.

More about Controlling a Led matrix or 7-segment displays with the MAX7219 or the MAX7221, in Arduino Playground.

Related:
- Arduino Uno + MAX7219 8x8 LED Matrix via SPI, using LedControl Library

How to identify pin 1 of 8x8 LED Matrix

This post show how to identify pin 1, and pin 16, of 8x8 LED Matrix.

---

Part I: Row Anode Column Cathode 8x8 LED Matrix, 1588BS as example. Current flow from pin 1 to pin 16 to make LED on row 5 col 8 ON.

Use the example of Row-Column Scanning an 8x8 LED matrix to show it work.

The connection between Arduino Uno and 8x8 LED Matrix is show here:

(It's recommended to add 220 ohm resisters to limit the current)

We need a test program to verify our connection, visit http://goo.gl/tXySxV, copy the example sketch of Walking bit on 8*8 LED Matrix, and download to Arduino Uno.

If your 8x8 LED Matrix have no marking for pin 1, we can use a multimeter to identify pin 1, and also pin 16.

This scheme diagram show when we apply +ve on pin 1 and -ve on pin 16, the LED on row 5 col 8 will be turn on.

Switch multimeter to diode test, the red lead will be +ve and black lead will be -ve.

Refer to the below video:

There are 4 possibility of pin 1 and 16, only one case will turn on a LED. When the LED (row 5 col 8) on, the pin connected to the RED lead of multimeter is pin 1.

---

Part II: Row Cathode Column Anode 8x8 LED Matrix, 1088AS as example. Current flow from pin 16 to pin 1 to make LED on row 5 col 8 ON.

Same procedure as in part I, with pin 1 on BLACK lead of multimeter.


Working example, refer to next post "Arduino Uno + SPI 8x8 LED Matrix, with MAX7219 LED driver".

Arduino Uno: scan LED Matrix in Timer Interrupt

The original tutorial "Row-columm Scanning to control an 8x8 LED Matrix" call refreshScreen() to draw the screen repeatly in main loop(). If anything in loop() have to do something for times, will block the program, and make the duty cycle (and the brightness) will become unstable. This example show how to scan LED Matrix in Timer Interrupt ISR, such that it will not be affect by the jobs in loop(). But the timing of Timer Interrupt will affect the performance. This video show how:

// 2-dimensional array of row pin numbers:
const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

int posX = 7;
int posY = 7;
int count = 30;
bool bg = false;

unsigned int timer1_counter;
int scanningRow = 0;

void setup() {
  Serial.begin(9600);
  
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  // initialize timer1 
  noInterrupts();           // disable all interrupts
  TCCR1A = 0;
  TCCR1B = 0;

  //timer1_counter for 1 sec, with prescaler=256
  //65536 - 16000000/256
  //timer1_counter = 3036;
  //timer1_counter for 0.5 sec, with prescaler=256
  //65536 - 16000000/(256*2)
  //timer1_counter = 34286;
  //timer1_counter for 0.1 sec, with prescaler=256
  //65536 - 16000000/(256*10)
  //timer1_counter = 59286;
  //timer1_counter for 0.001 sec, with prescaler=256
  //65536 - 16000000/(256*100)
  //timer1_counter = 64911;
  //timer1_counter for 0.0002 sec, with prescaler=256
  //65536 - 16000000/(256*500)
  timer1_counter = 65411;
  
  TCNT1 = timer1_counter;   // preload timer
  TCCR1B |= (1 << CS12);    // 256 prescaler 
  TIMSK1 |= (1 << TOIE1);   // enable timer overflow interrupt
  interrupts();             // enable all interrupts
  
  //init pixels
  for (int x = 0; x < 4; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = HIGH;
    }
  }
  for (int x = 4; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = LOW;
    }
  }
  
  pixels[1][3] = LOW;

}

ISR(TIMER1_OVF_vect)        // interrupt service routine 
{
  TCNT1 = timer1_counter;   // preload timer

  
  //scan LED Matrix in ISR
  digitalWrite(row[scanningRow], LOW);

  if(++scanningRow>=8){
    scanningRow = 0;
  }

  for (int thisCol = 0; thisCol < 8; thisCol++) {
    int thisPixel = pixels[scanningRow][thisCol];
    digitalWrite(col[thisCol], thisPixel);
  }
  digitalWrite(row[scanningRow], HIGH);
  
}

void loop() {
  //refreshScreen();
  
  //Do something, block the loop
  Serial.println("Hello!");
  //Serial.println("Hello! again");

}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}

Port ASCII font to Arduino + 8*8 LED Matrix

https://github.com/dhepper/font8x8 is a collection of header files containing a 8x8 bitmap font. In this example, the font8x8_basic.h is port to Arduino, to display the 8x8 font on LED Matrix.

/*
 *  Modify from Row-Column Scanning an 8x8 LED matrix tutorial
 *  http://arduino-er.blogspot.com/
 */
 
 /*
  *  The 8x8 font is ported from 
  *  https://github.com/dhepper/font8x8/blob/master/font8x8_basic.h
  */

byte font[128][8] = {
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0000 (nul)
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0001
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0002
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0003
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0004
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0005
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0006
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0007
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0008
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0009
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+000A
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+000B
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+000C
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+000D
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+000E
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+000F
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0010
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0011
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0012
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0013
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0014
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0015
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0016
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0017
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0018
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0019
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+001A
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+001B
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+001C
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+001D
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+001E
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+001F
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0020 (space)
    { 0x18, 0x3C, 0x3C, 0x18, 0x18, 0x00, 0x18, 0x00},   // U+0021 (!)
    { 0x36, 0x36, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0022 (")
    { 0x36, 0x36, 0x7F, 0x36, 0x7F, 0x36, 0x36, 0x00},   // U+0023 (#)
    { 0x0C, 0x3E, 0x03, 0x1E, 0x30, 0x1F, 0x0C, 0x00},   // U+0024 ($)
    { 0x00, 0x63, 0x33, 0x18, 0x0C, 0x66, 0x63, 0x00},   // U+0025 (%)
    { 0x1C, 0x36, 0x1C, 0x6E, 0x3B, 0x33, 0x6E, 0x00},   // U+0026 (&)
    { 0x06, 0x06, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0027 (')
    { 0x18, 0x0C, 0x06, 0x06, 0x06, 0x0C, 0x18, 0x00},   // U+0028 (()
    { 0x06, 0x0C, 0x18, 0x18, 0x18, 0x0C, 0x06, 0x00},   // U+0029 ())
    { 0x00, 0x66, 0x3C, 0xFF, 0x3C, 0x66, 0x00, 0x00},   // U+002A (*)
    { 0x00, 0x0C, 0x0C, 0x3F, 0x0C, 0x0C, 0x00, 0x00},   // U+002B (+)
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x0C, 0x0C, 0x06},   // U+002C (,)
    { 0x00, 0x00, 0x00, 0x3F, 0x00, 0x00, 0x00, 0x00},   // U+002D (-)
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x0C, 0x0C, 0x00},   // U+002E (.)
    { 0x60, 0x30, 0x18, 0x0C, 0x06, 0x03, 0x01, 0x00},   // U+002F (/)
    { 0x3E, 0x63, 0x73, 0x7B, 0x6F, 0x67, 0x3E, 0x00},   // U+0030 (0)
    { 0x0C, 0x0E, 0x0C, 0x0C, 0x0C, 0x0C, 0x3F, 0x00},   // U+0031 (1)
    { 0x1E, 0x33, 0x30, 0x1C, 0x06, 0x33, 0x3F, 0x00},   // U+0032 (2)
    { 0x1E, 0x33, 0x30, 0x1C, 0x30, 0x33, 0x1E, 0x00},   // U+0033 (3)
    { 0x38, 0x3C, 0x36, 0x33, 0x7F, 0x30, 0x78, 0x00},   // U+0034 (4)
    { 0x3F, 0x03, 0x1F, 0x30, 0x30, 0x33, 0x1E, 0x00},   // U+0035 (5)
    { 0x1C, 0x06, 0x03, 0x1F, 0x33, 0x33, 0x1E, 0x00},   // U+0036 (6)
    { 0x3F, 0x33, 0x30, 0x18, 0x0C, 0x0C, 0x0C, 0x00},   // U+0037 (7)
    { 0x1E, 0x33, 0x33, 0x1E, 0x33, 0x33, 0x1E, 0x00},   // U+0038 (8)
    { 0x1E, 0x33, 0x33, 0x3E, 0x30, 0x18, 0x0E, 0x00},   // U+0039 (9)
    { 0x00, 0x0C, 0x0C, 0x00, 0x00, 0x0C, 0x0C, 0x00},   // U+003A (:)
    { 0x00, 0x0C, 0x0C, 0x00, 0x00, 0x0C, 0x0C, 0x06},   // U+003B (//)
    { 0x18, 0x0C, 0x06, 0x03, 0x06, 0x0C, 0x18, 0x00},   // U+003C (<)
    { 0x00, 0x00, 0x3F, 0x00, 0x00, 0x3F, 0x00, 0x00},   // U+003D (=)
    { 0x06, 0x0C, 0x18, 0x30, 0x18, 0x0C, 0x06, 0x00},   // U+003E (>)
    { 0x1E, 0x33, 0x30, 0x18, 0x0C, 0x00, 0x0C, 0x00},   // U+003F (?)
    { 0x3E, 0x63, 0x7B, 0x7B, 0x7B, 0x03, 0x1E, 0x00},   // U+0040 (@)
    { 0x0C, 0x1E, 0x33, 0x33, 0x3F, 0x33, 0x33, 0x00},   // U+0041 (A)
    { 0x3F, 0x66, 0x66, 0x3E, 0x66, 0x66, 0x3F, 0x00},   // U+0042 (B)
    { 0x3C, 0x66, 0x03, 0x03, 0x03, 0x66, 0x3C, 0x00},   // U+0043 (C)
    { 0x1F, 0x36, 0x66, 0x66, 0x66, 0x36, 0x1F, 0x00},   // U+0044 (D)
    { 0x7F, 0x46, 0x16, 0x1E, 0x16, 0x46, 0x7F, 0x00},   // U+0045 (E)
    { 0x7F, 0x46, 0x16, 0x1E, 0x16, 0x06, 0x0F, 0x00},   // U+0046 (F)
    { 0x3C, 0x66, 0x03, 0x03, 0x73, 0x66, 0x7C, 0x00},   // U+0047 (G)
    { 0x33, 0x33, 0x33, 0x3F, 0x33, 0x33, 0x33, 0x00},   // U+0048 (H)
    { 0x1E, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x1E, 0x00},   // U+0049 (I)
    { 0x78, 0x30, 0x30, 0x30, 0x33, 0x33, 0x1E, 0x00},   // U+004A (J)
    { 0x67, 0x66, 0x36, 0x1E, 0x36, 0x66, 0x67, 0x00},   // U+004B (K)
    { 0x0F, 0x06, 0x06, 0x06, 0x46, 0x66, 0x7F, 0x00},   // U+004C (L)
    { 0x63, 0x77, 0x7F, 0x7F, 0x6B, 0x63, 0x63, 0x00},   // U+004D (M)
    { 0x63, 0x67, 0x6F, 0x7B, 0x73, 0x63, 0x63, 0x00},   // U+004E (N)
    { 0x1C, 0x36, 0x63, 0x63, 0x63, 0x36, 0x1C, 0x00},   // U+004F (O)
    { 0x3F, 0x66, 0x66, 0x3E, 0x06, 0x06, 0x0F, 0x00},   // U+0050 (P)
    { 0x1E, 0x33, 0x33, 0x33, 0x3B, 0x1E, 0x38, 0x00},   // U+0051 (Q)
    { 0x3F, 0x66, 0x66, 0x3E, 0x36, 0x66, 0x67, 0x00},   // U+0052 (R)
    { 0x1E, 0x33, 0x07, 0x0E, 0x38, 0x33, 0x1E, 0x00},   // U+0053 (S)
    { 0x3F, 0x2D, 0x0C, 0x0C, 0x0C, 0x0C, 0x1E, 0x00},   // U+0054 (T)
    { 0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x3F, 0x00},   // U+0055 (U)
    { 0x33, 0x33, 0x33, 0x33, 0x33, 0x1E, 0x0C, 0x00},   // U+0056 (V)
    { 0x63, 0x63, 0x63, 0x6B, 0x7F, 0x77, 0x63, 0x00},   // U+0057 (W)
    { 0x63, 0x63, 0x36, 0x1C, 0x1C, 0x36, 0x63, 0x00},   // U+0058 (X)
    { 0x33, 0x33, 0x33, 0x1E, 0x0C, 0x0C, 0x1E, 0x00},   // U+0059 (Y)
    { 0x7F, 0x63, 0x31, 0x18, 0x4C, 0x66, 0x7F, 0x00},   // U+005A (Z)
    { 0x1E, 0x06, 0x06, 0x06, 0x06, 0x06, 0x1E, 0x00},   // U+005B ([)
    { 0x03, 0x06, 0x0C, 0x18, 0x30, 0x60, 0x40, 0x00},   // U+005C (\)
    { 0x1E, 0x18, 0x18, 0x18, 0x18, 0x18, 0x1E, 0x00},   // U+005D (])
    { 0x08, 0x1C, 0x36, 0x63, 0x00, 0x00, 0x00, 0x00},   // U+005E (^)
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF},   // U+005F (_)
    { 0x0C, 0x0C, 0x18, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+0060 (`)
    { 0x00, 0x00, 0x1E, 0x30, 0x3E, 0x33, 0x6E, 0x00},   // U+0061 (a)
    { 0x07, 0x06, 0x06, 0x3E, 0x66, 0x66, 0x3B, 0x00},   // U+0062 (b)
    { 0x00, 0x00, 0x1E, 0x33, 0x03, 0x33, 0x1E, 0x00},   // U+0063 (c)
    { 0x38, 0x30, 0x30, 0x3e, 0x33, 0x33, 0x6E, 0x00},   // U+0064 (d)
    { 0x00, 0x00, 0x1E, 0x33, 0x3f, 0x03, 0x1E, 0x00},   // U+0065 (e)
    { 0x1C, 0x36, 0x06, 0x0f, 0x06, 0x06, 0x0F, 0x00},   // U+0066 (f)
    { 0x00, 0x00, 0x6E, 0x33, 0x33, 0x3E, 0x30, 0x1F},   // U+0067 (g)
    { 0x07, 0x06, 0x36, 0x6E, 0x66, 0x66, 0x67, 0x00},   // U+0068 (h)
    { 0x0C, 0x00, 0x0E, 0x0C, 0x0C, 0x0C, 0x1E, 0x00},   // U+0069 (i)
    { 0x30, 0x00, 0x30, 0x30, 0x30, 0x33, 0x33, 0x1E},   // U+006A (j)
    { 0x07, 0x06, 0x66, 0x36, 0x1E, 0x36, 0x67, 0x00},   // U+006B (k)
    { 0x0E, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x1E, 0x00},   // U+006C (l)
    { 0x00, 0x00, 0x33, 0x7F, 0x7F, 0x6B, 0x63, 0x00},   // U+006D (m)
    { 0x00, 0x00, 0x1F, 0x33, 0x33, 0x33, 0x33, 0x00},   // U+006E (n)
    { 0x00, 0x00, 0x1E, 0x33, 0x33, 0x33, 0x1E, 0x00},   // U+006F (o)
    { 0x00, 0x00, 0x3B, 0x66, 0x66, 0x3E, 0x06, 0x0F},   // U+0070 (p)
    { 0x00, 0x00, 0x6E, 0x33, 0x33, 0x3E, 0x30, 0x78},   // U+0071 (q)
    { 0x00, 0x00, 0x3B, 0x6E, 0x66, 0x06, 0x0F, 0x00},   // U+0072 (r)
    { 0x00, 0x00, 0x3E, 0x03, 0x1E, 0x30, 0x1F, 0x00},   // U+0073 (s)
    { 0x08, 0x0C, 0x3E, 0x0C, 0x0C, 0x2C, 0x18, 0x00},   // U+0074 (t)
    { 0x00, 0x00, 0x33, 0x33, 0x33, 0x33, 0x6E, 0x00},   // U+0075 (u)
    { 0x00, 0x00, 0x33, 0x33, 0x33, 0x1E, 0x0C, 0x00},   // U+0076 (v)
    { 0x00, 0x00, 0x63, 0x6B, 0x7F, 0x7F, 0x36, 0x00},   // U+0077 (w)
    { 0x00, 0x00, 0x63, 0x36, 0x1C, 0x36, 0x63, 0x00},   // U+0078 (x)
    { 0x00, 0x00, 0x33, 0x33, 0x33, 0x3E, 0x30, 0x1F},   // U+0079 (y)
    { 0x00, 0x00, 0x3F, 0x19, 0x0C, 0x26, 0x3F, 0x00},   // U+007A (z)
    { 0x38, 0x0C, 0x0C, 0x07, 0x0C, 0x0C, 0x38, 0x00},   // U+007B ({)
    { 0x18, 0x18, 0x18, 0x00, 0x18, 0x18, 0x18, 0x00},   // U+007C (|)
    { 0x07, 0x0C, 0x0C, 0x38, 0x0C, 0x0C, 0x07, 0x00},   // U+007D (})
    { 0x6E, 0x3B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},   // U+007E (~)
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}    // U+007F
};

// 2-dimensional array of row pin numbers:
const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

int count = 1000;

//char str[] = "01234567890abcdefghijklmopqrstuvwxyz";

char str[] = {
  0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 
  0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
  0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 
  0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
  0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 
  0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F,
  0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 
  0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F,
  0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 
  0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F,
  0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 
  0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F,
};

int strLen = sizeof(str);
int ptrChar = 0;

void setup() {

  
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }
  
  setupChar();

}

void loop() {

  // draw the screen:
  refreshScreen();
  
  if(count-- == 0){
    count = 1000;
    setupChar();
  }

}

void setupChar(){

  char c = str[ptrChar];

  for (int x = 0; x < 8; x++) {
    byte bitMask = 0x01;
    byte f = font[c][x];
    for (int y = 0; y < 8; y++) {
      if (f & bitMask){
        pixels[x][y] = LOW;
      }else{
        pixels[x][y] = HIGH;
      }
      bitMask = bitMask << 1;
    }
  }

  ptrChar++;
  if(ptrChar>=strLen){
    ptrChar = 0;
  }

}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}

Arduino example: Self adjust analogRead() to read Photoresistor

This example read analog input of Photoresistor, then turn on 8*8 LED Matrix accordingly.

- It self adjust by checking the maximun and minimum of analog input, then determine the level of light.
- If analog input is less than rejectMin or greater than rejectMax, it will be reject. It's assumed invalid due to bad contact of the breadboard.

Connection:
The resister connect between the photoresistor and GND is 10K ohm.

Program code:

/*
 *  Read Analog I/P from Photoresistor (Analog 0)
 *  and set LED Matrix accordingly
 *  http://arduino-er.blogspot.com/
 */

int PhotoResPin = 0;
int photoResVal = 0;
int photoResMax = 0x00;
int photoResMin = 0x3FF;
int level1, level2, level3, level4;
int level = 0;
const int levelMax = 4;
const int levelMin = 0;
const int NumOfLevel = 5;

const int rejectMin = 0x030;
const int rejectMax = 0x3CF;

// 2-dimensional array of row pin numbers:
const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

int count = 1000;

char str[] = "EDCBA";
int strLen = sizeof(str);
int ptrChar = 0;


typedef bool charMapType[8][8];

const charMapType charDummy = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType charMin = {
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1},
  {1, 1, 1, 1, 1, 1, 1, 1}
};

const charMapType char1 = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType char2 = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 1, 1, 1, 1, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType char3 = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType charMax = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 1, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType *charMap[5] = {&charMin, &char1, &char2, &char3, &charMax};

void setup() {
  
  Serial.begin(9600);
  
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  
  //setupScreen();
  setupChar();

}

void loop() {

  // draw the screen:
  refreshScreen();

  readPhotoRes();

}

void readPhotoRes(){
  
  int prvLevel = level;
  
  //read photoresistor from analog input
  photoResVal = analogRead(PhotoResPin);
  //Serial.println(photoResVal);

  if(photoResVal < rejectMin) return;  //assume invalid
  if(photoResVal > rejectMax) return;  //assume invalid
  
  if(photoResVal > photoResMax){
    photoResMax = photoResVal;
    adjLevel();
    level = levelMax;
  }else if(photoResVal < photoResMin){
    photoResMin = photoResVal;
    adjLevel();
    level = levelMin;
  }else{
    
    //check valid of photoResMax & photoResMin
    if(photoResMax > photoResMin){
      if(photoResVal < level1){
        level = 0;
      }else if(photoResVal < level2){
        level = 1;
      }else if(photoResVal < level3){
        level = 2;
      }else if(photoResVal < level4){
        level = 3;
      }else{
        level = levelMax;
      }
    }
  }
  
  if(prvLevel != level){
    setupChar();
  }
}

void adjLevel(){
  if(photoResMax > photoResMin){
    int div = (photoResMax - photoResMin)/NumOfLevel;
    level1 = photoResMin + div;
    level2 = level1 + div;
    level3 = level2 + div;
    level4 = level3 + div;
  }
}

void setupChar(){

  const charMapType *cMap = charMap[level];

  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      bool v = (*cMap)[x][y];
      
      if(v){
        pixels[x][y] = LOW;
      }else{
        pixels[x][y] = HIGH;
      }
    }
  }

}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}

How it work:

In the video, the wrong color of LED is due to recording fps. It's not too significant visually.

Bit mapping for 8*8 LED Matrix

This post show how to map char to bitmap for 8*8 LED Matrix. In the example code, only 5 char 'A'...'E' are implemented. The char in str[] will be displayed character-by-character.

/*
 *  Modify from Row-Column Scanning an 8x8 LED matrix tutorial
 *  http://arduino-er.blogspot.com/
 */


// 2-dimensional array of row pin numbers:
const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

int count = 1000;

char str[] = "EDCBA";
int strLen = sizeof(str);
int ptrChar = 0;


typedef bool charMapType[8][8];

const charMapType charDummy = {
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0},
  {0, 0, 0, 0, 0, 0, 0, 0}
};

const charMapType charA = {
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 0, 1, 1, 0, 0, 0},
  {0, 0, 1, 0, 0, 1, 0, 0},
  {0, 0, 1, 0, 0, 1, 0, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 0, 0, 0, 0, 1, 0},
  {1, 1, 0, 0, 0, 0, 1, 1},
  {1, 0, 0, 0, 0, 0, 0, 1}
};

const charMapType charB = {
  {1, 1, 1, 1, 1, 1, 0, 0},
  {0, 1, 0, 0, 0, 0, 1, 0},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 0, 0, 0, 0, 1, 0},
  {1, 1, 1, 1, 1, 1, 0, 0}
};

const charMapType charC = {
  {0, 1, 1, 1, 1, 1, 1, 0},
  {1, 0, 0, 0, 0, 0, 0, 1},
  {1, 0, 0, 0, 0, 0, 0, 1},
  {1, 0, 0, 0, 0, 0, 0, 0},
  {1, 0, 0, 0, 0, 0, 0, 0},
  {1, 0, 0, 0, 0, 0, 0, 1},
  {1, 0, 0, 0, 0, 0, 0, 1},
  {0, 1, 1, 1, 1, 1, 1, 0}
};

const charMapType charD = {
  {1, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {0, 1, 0, 0, 0, 0, 0, 1},
  {1, 1, 1, 1, 1, 1, 1, 0}
};

const charMapType charE = {
  {1, 1, 1, 1, 1, 1, 1, 1},
  {0, 1, 0, 0, 0, 0, 0, 0},
  {0, 1, 0, 0, 0, 0, 0, 0},
  {0, 1, 1, 1, 1, 1, 1, 0},
  {0, 1, 0, 0, 0, 0, 0, 0},
  {0, 1, 0, 0, 0, 0, 0, 0},
  {0, 1, 0, 0, 0, 0, 0, 0},
  {1, 1, 1, 1, 1, 1, 1, 1}
};


const charMapType *charMap[5] = {&charA, &charB, &charC, &charD, &charE};

void setup() {
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  
  //setupScreen();
  setupChar();

}

void loop() {

  // draw the screen:
  refreshScreen();
  
  if(count-- == 0){
    count = 1000;
    setupChar();
  }

}

void setupChar(){
  char c = str[ptrChar];
  int offset = c - 'A';
  
  const charMapType *cMap = charMap[offset];
  //charMapType *cMap = &charDummy;
  
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      bool v = (*cMap)[x][y];
      
      if(v){
        pixels[x][y] = LOW;
      }else{
        pixels[x][y] = HIGH;
      }
    }
  }
  
  ptrChar++;
  if(ptrChar>=strLen-1){
    ptrChar = 0;
  }

}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}

Walking bit on 8*8 LED Matrix, with Arduino Uno

Last post have a 8*8 LED Matrix, work with Arduino Uno.

It's another test program to turn ON/OFF a walking bit on 8*8 LED Matrix, to clarify all LED work as expect.

/*
 *  Modify from Row-Column Scanning an 8x8 LED matrix tutorial
 *  http://arduino-er.blogspot.com/
 */
/*
  Row-Column Scanning an 8x8 LED matrix with X-Y input

 This example controls an 8x8 LED matrix using two analog inputs

 created 27 May 2009
 modified 30 Aug 2011
 by Tom Igoe

 This example works for the Lumex  LDM-24488NI Matrix. See
 http://sigma.octopart.com/140413/datasheet/Lumex-LDM-24488NI.pdf
 for the pin connections

 For other LED cathode column matrixes, you should only need to change
 the pin numbers in the row[] and column[] arrays

 rows are the anodes
 cols are the cathodes
 ---------

 Pin numbers:
 Matrix:
 * Digital pins 2 through 13,
 * analog pins 2 through 5 used as digital 16 through 19
 Potentiometers:
 * center pins are attached to analog pins 0 and 1, respectively
 * side pins attached to +5V and ground, respectively.

 This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/RowColumnScanning

 see also http://www.tigoe.net/pcomp/code/category/arduinowiring/514 for more
 */


// 2-dimensional array of row pin numbers:
const int row[8] = {
  2, 7, 19, 5, 13, 18, 12, 16
};

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6, 11, 10, 3, 17, 4, 8, 9
};

// 2-dimensional array of pixels:
int pixels[8][8];

int posX = 7;
int posY = 7;
int count = 30;
bool bg = false;

void setup() {
  // initialize the I/O pins as outputs
  // iterate over the pins:
  for (int thisPin = 0; thisPin < 8; thisPin++) {
    // initialize the output pins:
    pinMode(col[thisPin], OUTPUT);
    pinMode(row[thisPin], OUTPUT);
    // take the col pins (i.e. the cathodes) high to ensure that
    // the LEDS are off:
    digitalWrite(col[thisPin], HIGH);
  }

  setupScreen();

}

void loop() {

  // draw the screen:
  refreshScreen();
  
  if(count-- == 0){
    count = 500;
    if(posX--==0){
      posX = 7;
      if(posY--==0){
        posY = 7;
        bg = !bg;
      }
    }
    setupScreen();

  }
}

void setupScreen(){
  if(bg){
    //ON all others
    for (int x = 0; x < 8; x++) {
      for (int y = 0; y < 8; y++) {
        pixels[x][y] = LOW;
      }
    }
    
    //OFF current pos
    pixels[posX][posY] = HIGH;
  }else{
    //OFF all others
    for (int x = 0; x < 8; x++) {
      for (int y = 0; y < 8; y++) {
        pixels[x][y] = HIGH;
      }
    }
    
    //ON current pos
    pixels[posX][posY] = LOW;
  }
}

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}

Test 8*8 LED Matrix with Arduino Uno R3

Just purchased a Arduino Start Kit with Arduino Uno R3, and some components. It's the first test for the 8*8 LED Matrix.


Basically it follow the tutorial of Row-columm Scanning to control an 8x8 LED Matrix, can be open in in Arduino IDE (1.5.7 in my case), File -> Examples -> 07.Display -> RowColumnScanning.

The connection follow the diagram:

To make it simple, I remove the two potentiometers, and ignore readSensors() in the code.

8 pcs of 220 ohm resistors are added  to limit the current, to protect my board.

The 8*8 LED Matrix marked 1588BS, it should be the part number or model number. Actually I cannot find any marking to recognize the pin 1. I place it by chance.

To turn on any spot, set it low in the code:

  pixels[x][y] = LOW;

Next:
- Implement walking bit to test all bit ON/OFF.