8×8 LED矩阵MAX7219教程，通过蓝牙滚动文本和Android控制

在本 Arduino 教程中，我们将学习如何使用 MAX7219 驱动器和 Arduino 板控制 8×8 LED 矩阵。您可以观看以下视频或阅读下面的书面教程了解更多详情。

概览

我们将做三个例子，第一个我们将解释 MAX7219 的基本工作原理，在第二个例子中我们将看到 8×8 LED 矩阵上的滚动文本是如何工作的，在第三个例子中我们将控制它们通过蓝牙和自定义构建的 Android 应用程序。

MAX7219

现在让我们仔细看看 MAX7219 驱动器。该 IC 能够驱动 64 个单独的 LED，同时仅使用 3 根线与 Arduino 通信，而且我们可以菊花链多个驱动器和矩阵，仍然使用相同的 3 根线。

64 个 LED 由 IC 的 16 个输出引脚驱动。现在的问题是这怎么可能。好吧，同时点亮的 LED 的最大数量实际上是 8 个。 LED 排列为 8×8 组的行和列。因此，MAX7219 在很短的时间内激活每一列，同时它也驱动每一行。因此，通过快速切换列和行，人眼只会注意到连续的光。

请注意常见的 8×8 LED 矩阵的引脚是如何在内部排列的，因此如果您是自己构建矩阵，则应该考虑它。

另请注意，MAX7219 的通用分线板在 5V 和 IC 引脚 18 之间带有一个电阻器。该电阻器用于设置亮度或流向 LED 的电流。

IC数据表中的下表显示了我们应该根据LED的正向压降使用的电阻值。

电路原理图

现在让我们将 8×8 LED 矩阵模块连接到 Arduino 板。电路原理图如下：

模块的 VCC 和 GND 连接到 Arduino 的 5V 和 GND 引脚，其他三个引脚 DIN、CLK 和 CS 连接到 Arduino 板的任何数字引脚。如果我们想连接多个模块，我们只需将前一个分线板的输出引脚连接到新模块的输入引脚。其实这些管脚都是一样的，只是之前板子的DOUT管脚接新板子的DIN管脚。

您可以从以下链接获取本 Arduino 教程所需的组件：

8×8 LED MAX7219 点阵模块...... ..
HC-05蓝牙模块…………………………
Arduino 开发板…………………………………………..
面包板和跳线……………………

基本 MAX7219 Arduino 代码

连接模块后，我们就可以查看第一个示例的 Arduino 代码了。我们将使用可以从 GitHub 下载的 MaxMatrix 库。

/*
      8x8 LED Matrix MAX7219 Example 01

   by Dejan Nedelkovski, www.HowToMechatronics.com

   Based on the following library:
   GitHub | riyas-org/max7219  https://github.com/riyas-org/max7219
*/

#include <MaxMatrix.h>

int DIN = 7;   // DIN pin of MAX7219 module
int CLK = 6;   // CLK pin of MAX7219 module
int CS = 5;    // CS pin of MAX7219 module
int maxInUse = 1;


MaxMatrix m(DIN, CS, CLK, maxInUse); 

char A[] = {4, 8,
            B01111110,
            B00010001,
            B00010001,
            B01111110,
           };

char B[] = {4, 8,
            B01111111,
            B01001001,
            B01001001,
            B00110110,
           };

char smile01[] = {8, 8,
                  B00111100,
                  B01000010,
                  B10010101,
                  B10100001,
                  B10100001,
                  B10010101,
                  B01000010,
                  B00111100
                 };
char smile02[] = {8, 8,
                  B00111100,
                  B01000010,
                  B10010101,
                  B10010001,
                  B10010001,
                  B10010101,
                  B01000010,
                  B00111100
                 };
char smile03[] = {8, 8,
                  B00111100,
                  B01000010,
                  B10100101,
                  B10010001,
                  B10010001,
                  B10100101,
                  B01000010,
                  B00111100
                 };

void setup() {
  m.init(); // MAX7219 initialization
  m.setIntensity(8); // initial led matrix intensity, 0-15
}

void loop() {
  // Seting the LEDs On or Off at x,y or row,column position
  m.setDot(6,2,true); 
  delay(1000);
  m.setDot(6,3,true);
  delay(1000);
  m.clear(); // Clears the display
  for (int i=0; i<8; i++){
    m.setDot(i,i,true);
    delay(300);
  }
  m.clear();
  // Displaying the character at x,y (upper left corner of the character)  
  m.writeSprite(2, 0, A);
  delay(1000);

  m.writeSprite(2, 0, B);
  delay(1000);

  m.writeSprite(0, 0, smile01);
  delay(1000);
  
  m.writeSprite(0, 0, smile02);
  delay(1000);
  
  m.writeSprite(0, 0, smile03);
  delay(1000);
  
  for (int i=0; i<8; i++){
    m.shiftLeft(false,false);
    delay(300);
  }
  m.clear();

}
Code language: Arduino (arduino)

说明： 所以首先我们需要包含 MaxMatrix.h 库，定义模块连接的引脚，设置我们使用的模块数量并定义 MaxMatrix 对象。

为了显示字符，我们需要在字符或字节数组中定义它们，这里我有几个例子。我们可以注意到这些位是如何形成实际上是零和一的字符的。在这种情况下，它们会旋转 90 度，但库示例建议以这样的方式使用它们，以便以后更容易实现用于滚动文本的 shiftLeft 自定义函数。

在设置部分，我们只需要初始化模块并设置 LED 的亮度。在使用 setDot() 函数的循环部分，我们可以将任何单个 LED 设置为在 X、Y 或 Row/Column 位置点亮，并使用 clear() 函数可以清除显示。

为了显示预定义的字符，我们使用 writeSprite() 函数，前两个参数是字符左上角的 X 和 Y 位置。最后使用 shiftLeft() 函数向左移动或滚动字符。

8×8 LED 矩阵滚动Arduino代码

接下来让我们看一下滚动文本示例，看看有什么不同。您将在代码下方找到其说明。

/*
      8x8 LED Matrix MAX7219 Scrolling Text Example

   Based on the following library:
   GitHub | riyas-org/max7219  https://github.com/riyas-org/max7219
*/


#include <MaxMatrix.h>
#include <avr/pgmspace.h>

PROGMEM const unsigned char CH[] = {
  3, 8, B00000000, B00000000, B00000000, B00000000, B00000000, // space
  1, 8, B01011111, B00000000, B00000000, B00000000, B00000000, // !
  3, 8, B00000011, B00000000, B00000011, B00000000, B00000000, // "
  5, 8, B00010100, B00111110, B00010100, B00111110, B00010100, // #
  4, 8, B00100100, B01101010, B00101011, B00010010, B00000000, // $
  5, 8, B01100011, B00010011, B00001000, B01100100, B01100011, // %
  5, 8, B00110110, B01001001, B01010110, B00100000, B01010000, // &
  1, 8, B00000011, B00000000, B00000000, B00000000, B00000000, // '
  3, 8, B00011100, B00100010, B01000001, B00000000, B00000000, // (
  3, 8, B01000001, B00100010, B00011100, B00000000, B00000000, // )
  5, 8, B00101000, B00011000, B00001110, B00011000, B00101000, // *
  5, 8, B00001000, B00001000, B00111110, B00001000, B00001000, // +
  2, 8, B10110000, B01110000, B00000000, B00000000, B00000000, // ,
  4, 8, B00001000, B00001000, B00001000, B00001000, B00000000, // -
  2, 8, B01100000, B01100000, B00000000, B00000000, B00000000, // .
  4, 8, B01100000, B00011000, B00000110, B00000001, B00000000, // /
  4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // 0
  3, 8, B01000010, B01111111, B01000000, B00000000, B00000000, // 1
  4, 8, B01100010, B01010001, B01001001, B01000110, B00000000, // 2
  4, 8, B00100010, B01000001, B01001001, B00110110, B00000000, // 3
  4, 8, B00011000, B00010100, B00010010, B01111111, B00000000, // 4
  4, 8, B00100111, B01000101, B01000101, B00111001, B00000000, // 5
  4, 8, B00111110, B01001001, B01001001, B00110000, B00000000, // 6
  4, 8, B01100001, B00010001, B00001001, B00000111, B00000000, // 7
  4, 8, B00110110, B01001001, B01001001, B00110110, B00000000, // 8
  4, 8, B00000110, B01001001, B01001001, B00111110, B00000000, // 9
  2, 8, B01010000, B00000000, B00000000, B00000000, B00000000, // :
  2, 8, B10000000, B01010000, B00000000, B00000000, B00000000, // ;
  3, 8, B00010000, B00101000, B01000100, B00000000, B00000000, // <
  3, 8, B00010100, B00010100, B00010100, B00000000, B00000000, // =
  3, 8, B01000100, B00101000, B00010000, B00000000, B00000000, // >
  4, 8, B00000010, B01011001, B00001001, B00000110, B00000000, // ?
  5, 8, B00111110, B01001001, B01010101, B01011101, B00001110, // @
  4, 8, B01111110, B00010001, B00010001, B01111110, B00000000, // A
  4, 8, B01111111, B01001001, B01001001, B00110110, B00000000, // B
  4, 8, B00111110, B01000001, B01000001, B00100010, B00000000, // C
  4, 8, B01111111, B01000001, B01000001, B00111110, B00000000, // D
  4, 8, B01111111, B01001001, B01001001, B01000001, B00000000, // E
  4, 8, B01111111, B00001001, B00001001, B00000001, B00000000, // F
  4, 8, B00111110, B01000001, B01001001, B01111010, B00000000, // G
  4, 8, B01111111, B00001000, B00001000, B01111111, B00000000, // H
  3, 8, B01000001, B01111111, B01000001, B00000000, B00000000, // I
  4, 8, B00110000, B01000000, B01000001, B00111111, B00000000, // J
  4, 8, B01111111, B00001000, B00010100, B01100011, B00000000, // K
  4, 8, B01111111, B01000000, B01000000, B01000000, B00000000, // L
  5, 8, B01111111, B00000010, B00001100, B00000010, B01111111, // M
  5, 8, B01111111, B00000100, B00001000, B00010000, B01111111, // N
  4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // O
  4, 8, B01111111, B00001001, B00001001, B00000110, B00000000, // P
  4, 8, B00111110, B01000001, B01000001, B10111110, B00000000, // Q
  4, 8, B01111111, B00001001, B00001001, B01110110, B00000000, // R
  4, 8, B01000110, B01001001, B01001001, B00110010, B00000000, // S
  5, 8, B00000001, B00000001, B01111111, B00000001, B00000001, // T
  4, 8, B00111111, B01000000, B01000000, B00111111, B00000000, // U
  5, 8, B00001111, B00110000, B01000000, B00110000, B00001111, // V
  5, 8, B00111111, B01000000, B00111000, B01000000, B00111111, // W
  5, 8, B01100011, B00010100, B00001000, B00010100, B01100011, // X
  5, 8, B00000111, B00001000, B01110000, B00001000, B00000111, // Y
  4, 8, B01100001, B01010001, B01001001, B01000111, B00000000, // Z
  2, 8, B01111111, B01000001, B00000000, B00000000, B00000000, // [
  4, 8, B00000001, B00000110, B00011000, B01100000, B00000000, // \ backslash
  2, 8, B01000001, B01111111, B00000000, B00000000, B00000000, // ]
  3, 8, B00000010, B00000001, B00000010, B00000000, B00000000, // hat
  4, 8, B01000000, B01000000, B01000000, B01000000, B00000000, // _
  2, 8, B00000001, B00000010, B00000000, B00000000, B00000000, // `
  4, 8, B00100000, B01010100, B01010100, B01111000, B00000000, // a
  4, 8, B01111111, B01000100, B01000100, B00111000, B00000000, // b
  4, 8, B00111000, B01000100, B01000100, B00101000, B00000000, // c
  4, 8, B00111000, B01000100, B01000100, B01111111, B00000000, // d
  4, 8, B00111000, B01010100, B01010100, B00011000, B00000000, // e
  3, 8, B00000100, B01111110, B00000101, B00000000, B00000000, // f
  4, 8, B10011000, B10100100, B10100100, B01111000, B00000000, // g
  4, 8, B01111111, B00000100, B00000100, B01111000, B00000000, // h
  3, 8, B01000100, B01111101, B01000000, B00000000, B00000000, // i
  4, 8, B01000000, B10000000, B10000100, B01111101, B00000000, // j
  4, 8, B01111111, B00010000, B00101000, B01000100, B00000000, // k
  3, 8, B01000001, B01111111, B01000000, B00000000, B00000000, // l
  5, 8, B01111100, B00000100, B01111100, B00000100, B01111000, // m
  4, 8, B01111100, B00000100, B00000100, B01111000, B00000000, // n
  4, 8, B00111000, B01000100, B01000100, B00111000, B00000000, // o
  4, 8, B11111100, B00100100, B00100100, B00011000, B00000000, // p
  4, 8, B00011000, B00100100, B00100100, B11111100, B00000000, // q
  4, 8, B01111100, B00001000, B00000100, B00000100, B00000000, // r
  4, 8, B01001000, B01010100, B01010100, B00100100, B00000000, // s
  3, 8, B00000100, B00111111, B01000100, B00000000, B00000000, // t
  4, 8, B00111100, B01000000, B01000000, B01111100, B00000000, // u
  5, 8, B00011100, B00100000, B01000000, B00100000, B00011100, // v
  5, 8, B00111100, B01000000, B00111100, B01000000, B00111100, // w
  5, 8, B01000100, B00101000, B00010000, B00101000, B01000100, // x
  4, 8, B10011100, B10100000, B10100000, B01111100, B00000000, // y
  3, 8, B01100100, B01010100, B01001100, B00000000, B00000000, // z
  3, 8, B00001000, B00110110, B01000001, B00000000, B00000000, // {
  1, 8, B01111111, B00000000, B00000000, B00000000, B00000000, // |
  3, 8, B01000001, B00110110, B00001000, B00000000, B00000000, // }
  4, 8, B00001000, B00000100, B00001000, B00000100, B00000000, // ~
};

int DIN = 7;   // DIN pin of MAX7219 module
int CLK = 6;   // CLK pin of MAX7219 module
int CS = 5;    // CS pin of MAX7219 module
int maxInUse = 2;

MaxMatrix m(DIN, CS, CLK, maxInUse);

byte buffer[10];

char text[]= "HowToMechatronics.com  "; // Scrolling text

void setup() {
  m.init(); // module initialize
  m.setIntensity(15); // dot matix intensity 0-15
}

void loop() {

  printStringWithShift(text, 100); // (text, scrolling speed)

}
// Display=the extracted characters with scrolling
void printCharWithShift(char c, int shift_speed) {
  if (c < 32) return;
  c -= 32;
  memcpy_P(buffer, CH + 7 * c, 7);
  m.writeSprite(32, 0, buffer);
  m.setColumn(32 + buffer[0], 0);

  for (int i = 0; i < buffer[0] + 1; i++)
  {
    delay(shift_speed);
    m.shiftLeft(false, false);
  }
}
// Extract the characters from the text string
void printStringWithShift(char* s, int shift_speed) {
  while (*s != 0) {
    printCharWithShift(*s, shift_speed);
    s++;
  }
}Code language: Arduino (arduino)

说明： 在这里，我们必须为 PROGMEN 添加一个附加库，它是变量修饰符，用于将数据存储在闪存而不是 SRAM 中。当我们有一个较大的静态变量数据库时，例如在这种情况下定义字母和字符，最好将它们存储在闪存中，因为它比 SRAM 的 2K 字节大得多，32K 字节。

接下来使用字符数组定义滚动文本，在循环部分中，自定义函数 printStringWithShift 以第二个参数定义的滚动速度（以毫秒为单位）在 LED 矩阵上打印滚动文本。这个自定义函数做的第一件事就是从文本字符串中提取字符，然后在led矩阵上显示这些滚动字符。

通过蓝牙控制 8×8 LED 矩阵的安卓应用

一旦我们了解了 MAX7219 的工作原理，现在我们可以制作第三个示例，这是一个实用的 Arduino 项目，我们将构建一个定制的 Android 应用程序来通过蓝牙通信控制 LED 矩阵。在继续之前，我建议您查看我的详细教程，了解如何使用 HC-05 蓝牙模块以及如何使用 MIT App Inventor 在线应用程序构建自定义 Android 应用程序。

这是 Arduino 代码，现在让我们看看与上一个示例相比的修改。

/*
      8x8 LED Matrix MAX7219 Scrolling Text
          Android Control via Bluetooth

   by Dejan Nedelkovski, www.HowToMechatronics.com

   Based on the following library:
   GitHub | riyas-org/max7219  https://github.com/riyas-org/max7219
*/

#include <MaxMatrix.h>
#include <SoftwareSerial.h>
#include <avr/pgmspace.h>

PROGMEM const unsigned char CH[] = {
  3, 8, B00000000, B00000000, B00000000, B00000000, B00000000, // space
  1, 8, B01011111, B00000000, B00000000, B00000000, B00000000, // !
  3, 8, B00000011, B00000000, B00000011, B00000000, B00000000, // "
  5, 8, B00010100, B00111110, B00010100, B00111110, B00010100, // #
  4, 8, B00100100, B01101010, B00101011, B00010010, B00000000, // $
  5, 8, B01100011, B00010011, B00001000, B01100100, B01100011, // %
  5, 8, B00110110, B01001001, B01010110, B00100000, B01010000, // &
  1, 8, B00000011, B00000000, B00000000, B00000000, B00000000, // '
  3, 8, B00011100, B00100010, B01000001, B00000000, B00000000, // (
  3, 8, B01000001, B00100010, B00011100, B00000000, B00000000, // )
  5, 8, B00101000, B00011000, B00001110, B00011000, B00101000, // *
  5, 8, B00001000, B00001000, B00111110, B00001000, B00001000, // +
  2, 8, B10110000, B01110000, B00000000, B00000000, B00000000, // ,
  4, 8, B00001000, B00001000, B00001000, B00001000, B00000000, // -
  2, 8, B01100000, B01100000, B00000000, B00000000, B00000000, // .
  4, 8, B01100000, B00011000, B00000110, B00000001, B00000000, // /
  4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // 0
  3, 8, B01000010, B01111111, B01000000, B00000000, B00000000, // 1
  4, 8, B01100010, B01010001, B01001001, B01000110, B00000000, // 2
  4, 8, B00100010, B01000001, B01001001, B00110110, B00000000, // 3
  4, 8, B00011000, B00010100, B00010010, B01111111, B00000000, // 4
  4, 8, B00100111, B01000101, B01000101, B00111001, B00000000, // 5
  4, 8, B00111110, B01001001, B01001001, B00110000, B00000000, // 6
  4, 8, B01100001, B00010001, B00001001, B00000111, B00000000, // 7
  4, 8, B00110110, B01001001, B01001001, B00110110, B00000000, // 8
  4, 8, B00000110, B01001001, B01001001, B00111110, B00000000, // 9
  2, 8, B01010000, B00000000, B00000000, B00000000, B00000000, // :
  2, 8, B10000000, B01010000, B00000000, B00000000, B00000000, // ;
  3, 8, B00010000, B00101000, B01000100, B00000000, B00000000, // <
  3, 8, B00010100, B00010100, B00010100, B00000000, B00000000, // =
  3, 8, B01000100, B00101000, B00010000, B00000000, B00000000, // >
  4, 8, B00000010, B01011001, B00001001, B00000110, B00000000, // ?
  5, 8, B00111110, B01001001, B01010101, B01011101, B00001110, // @
  4, 8, B01111110, B00010001, B00010001, B01111110, B00000000, // A
  4, 8, B01111111, B01001001, B01001001, B00110110, B00000000, // B
  4, 8, B00111110, B01000001, B01000001, B00100010, B00000000, // C
  4, 8, B01111111, B01000001, B01000001, B00111110, B00000000, // D
  4, 8, B01111111, B01001001, B01001001, B01000001, B00000000, // E
  4, 8, B01111111, B00001001, B00001001, B00000001, B00000000, // F
  4, 8, B00111110, B01000001, B01001001, B01111010, B00000000, // G
  4, 8, B01111111, B00001000, B00001000, B01111111, B00000000, // H
  3, 8, B01000001, B01111111, B01000001, B00000000, B00000000, // I
  4, 8, B00110000, B01000000, B01000001, B00111111, B00000000, // J
  4, 8, B01111111, B00001000, B00010100, B01100011, B00000000, // K
  4, 8, B01111111, B01000000, B01000000, B01000000, B00000000, // L
  5, 8, B01111111, B00000010, B00001100, B00000010, B01111111, // M
  5, 8, B01111111, B00000100, B00001000, B00010000, B01111111, // N
  4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // O
  4, 8, B01111111, B00001001, B00001001, B00000110, B00000000, // P
  4, 8, B00111110, B01000001, B01000001, B10111110, B00000000, // Q
  4, 8, B01111111, B00001001, B00001001, B01110110, B00000000, // R
  4, 8, B01000110, B01001001, B01001001, B00110010, B00000000, // S
  5, 8, B00000001, B00000001, B01111111, B00000001, B00000001, // T
  4, 8, B00111111, B01000000, B01000000, B00111111, B00000000, // U
  5, 8, B00001111, B00110000, B01000000, B00110000, B00001111, // V
  5, 8, B00111111, B01000000, B00111000, B01000000, B00111111, // W
  5, 8, B01100011, B00010100, B00001000, B00010100, B01100011, // X
  5, 8, B00000111, B00001000, B01110000, B00001000, B00000111, // Y
  4, 8, B01100001, B01010001, B01001001, B01000111, B00000000, // Z
  2, 8, B01111111, B01000001, B00000000, B00000000, B00000000, // [
  4, 8, B00000001, B00000110, B00011000, B01100000, B00000000, // \ backslash
  2, 8, B01000001, B01111111, B00000000, B00000000, B00000000, // ]
  3, 8, B00000010, B00000001, B00000010, B00000000, B00000000, // hat
  4, 8, B01000000, B01000000, B01000000, B01000000, B00000000, // _
  2, 8, B00000001, B00000010, B00000000, B00000000, B00000000, // `
  4, 8, B00100000, B01010100, B01010100, B01111000, B00000000, // a
  4, 8, B01111111, B01000100, B01000100, B00111000, B00000000, // b
  4, 8, B00111000, B01000100, B01000100, B00101000, B00000000, // c
  4, 8, B00111000, B01000100, B01000100, B01111111, B00000000, // d
  4, 8, B00111000, B01010100, B01010100, B00011000, B00000000, // e
  3, 8, B00000100, B01111110, B00000101, B00000000, B00000000, // f
  4, 8, B10011000, B10100100, B10100100, B01111000, B00000000, // g
  4, 8, B01111111, B00000100, B00000100, B01111000, B00000000, // h
  3, 8, B01000100, B01111101, B01000000, B00000000, B00000000, // i
  4, 8, B01000000, B10000000, B10000100, B01111101, B00000000, // j
  4, 8, B01111111, B00010000, B00101000, B01000100, B00000000, // k
  3, 8, B01000001, B01111111, B01000000, B00000000, B00000000, // l
  5, 8, B01111100, B00000100, B01111100, B00000100, B01111000, // m
  4, 8, B01111100, B00000100, B00000100, B01111000, B00000000, // n
  4, 8, B00111000, B01000100, B01000100, B00111000, B00000000, // o
  4, 8, B11111100, B00100100, B00100100, B00011000, B00000000, // p
  4, 8, B00011000, B00100100, B00100100, B11111100, B00000000, // q
  4, 8, B01111100, B00001000, B00000100, B00000100, B00000000, // r
  4, 8, B01001000, B01010100, B01010100, B00100100, B00000000, // s
  3, 8, B00000100, B00111111, B01000100, B00000000, B00000000, // t
  4, 8, B00111100, B01000000, B01000000, B01111100, B00000000, // u
  5, 8, B00011100, B00100000, B01000000, B00100000, B00011100, // v
  5, 8, B00111100, B01000000, B00111100, B01000000, B00111100, // w
  5, 8, B01000100, B00101000, B00010000, B00101000, B01000100, // x
  4, 8, B10011100, B10100000, B10100000, B01111100, B00000000, // y
  3, 8, B01100100, B01010100, B01001100, B00000000, B00000000, // z
  3, 8, B00001000, B00110110, B01000001, B00000000, B00000000, // {
  1, 8, B01111111, B00000000, B00000000, B00000000, B00000000, // |
  3, 8, B01000001, B00110110, B00001000, B00000000, B00000000, // }
  4, 8, B00001000, B00000100, B00001000, B00000100, B00000000, // ~
};

int dIn = 7;   // DIN pin of MAX7219 module
int clk = 6;   // CLK pin of MAX7219 module
int cs = 5;    // CS pin of MAX7219 module

int maxInUse = 2;    // Number of MAX7219's connected

MaxMatrix m(dIn, cs, clk, maxInUse);
SoftwareSerial Bluetooth(8, 7); // Bluetooth

byte buffer[10];
char incomebyte;
int scrollSpeed = 100;
char text[100] = "HowToMechatronics.com  "; // Initial text message
int brightness = 15;
int count = 0;
char indicator;

void setup() {
  m.init(); // MAX7219 initialization
  m.setIntensity(brightness); // initial led matrix intensity, 0-15
  Bluetooth.begin(38400); // Default communication rate of the Bluetooth module
}

void loop() {
  // Printing the text
  printStringWithShift(text, scrollSpeed);
  
  if (Bluetooth.available()) {   // Checks whether data is comming from the serial port
    indicator = Bluetooth.read();   // Starts reading the serial port, the first byte from the incoming data
    // If we have pressed the "Send" button from the Android App, clear the previous text
    if (indicator == '1') {
      for (int i = 0; i < 100; i++) {
        text[i] = 0;
        m.clear();
      }
      // Read the whole data/string comming from the phone and put it into text[] array.
      while (Bluetooth.available()) {
        incomebyte = Bluetooth.read();
        text[count] = incomebyte;
        count++;
      }
      count = 0;
    }
    // Adjusting the Scrolling Speed
    else if (indicator == '2') {
      String sS = Bluetooth.readString();
      scrollSpeed = 150 - sS.toInt(); // Milliseconds, subtraction because lower value means higher scrolling speed
    }
    // Adjusting the brightness
    else if (indicator == '3') {
      String sB = Bluetooth.readString();
      brightness = sB.toInt();
      m.setIntensity(brightness);
    }
  }

}

void printCharWithShift(char c, int shift_speed) {
  if (c < 32) return;
  c -= 32;
  memcpy_P(buffer, CH + 7 * c, 7);
  m.writeSprite(32, 0, buffer);
  m.setColumn(32 + buffer[0], 0);

  for (int i = 0; i < buffer[0] + 1; i++)
  {
    delay(shift_speed);
    m.shiftLeft(false, false);
  }
}

void printStringWithShift(char* s, int shift_speed) {
  while (*s != 0) {
    printCharWithShift(*s, shift_speed);
    s++;
  }
}

void printString(char* s)
{
  int col = 0;
  while (*s != 0)
  {
    if (*s < 32) continue;
    char c = *s - 32;
    memcpy_P(buffer, CH + 7 * c, 7);
    m.writeSprite(col, 0, buffer);
    m.setColumn(col + buffer[0], 0);
    col += buffer[0] + 1;
    s++;
  }
}Code language: Arduino (arduino)

说明： 首先，我们需要包含 SoftwareSerial.h 库，它将启用蓝牙通信并定义程序所需的一些变量。在设置部分，我们需要将蓝牙初始化为其默认波特率 38400 比特每秒。我将初始短信设置为“HowToMechatronics.com”，滚动速度延迟 100 毫秒。

接下来，在循环部分，我们使用 Bluetooth.available() 函数检查是否有来自串行端口的传入数据，如果是，则使用 Bluetooth.read 函数开始读取串行端口，每次迭代一个字节。因此，第一个传入的字节将始终存储在“indicator”变量中，并根据它选择是否更改文本消息、滚动速度或 LED 矩阵的亮度。

如果我们查看 Android 应用程序代码块，我们会注意到，当单击“发送”按钮时，首先我们发送指示字节，在本例中为“1”，这意味着我们想要更改文本消息。为此，在 Arduino 端，我们将清除整个字符数组并清除 LED 矩阵显示。然后在“while”循环中，我们将读取串口中的其余数据，也就是在 Android 应用的文本框中输入的消息。

如果指示变量是“2”，这意味着我们已经改变了滚动速度滑块的位置，所以我们将使用 Bluetooth.readString() 函数读取它的新值并调整滚动速度。以同样的方式调整 LED 的亮度。

在这里你可以下载安卓应用：

适用于 Arduino 8x8 LED 矩阵控制的 AndrodApp

1 个文件 1.48 MB 下载

适用于 Arduino 8×8 LED 矩阵控制的 AndrodApp .aia 文件

1 个文件 34.06 KB 下载

这就是本教程的几乎所有内容，如果您有任何问题，可以使用下面的评论部分。

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