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常规的远距离显示器件多采用点阵屏的方式，其最小的单元在原理上与点阵模块十分相近，均是采用行列扫描的方式。

以基于MAX7219的点阵模块为例，其原理图见图1所示。此外，为了显示更为丰富的内容，还可以级联的方式将多个点阵模块串联起来使用。

图1 原理图 

在只有单个点阵模块的情况下，也可通过快速切换的方式来显示更多的内容。

下面就以地奇星开发板与点阵模块相配合来实现一个显示“Happy New Year”的输出效果的示例。

使MAX7219输出字节数据的函数为：

void Write_Max7219_byte(char DATA)
{   
   char i;
   CS_SetLow();
   R_BSP_SoftwareDelay(5, BSP_DELAY_UNITS_MICROSECONDS);
   for(i=8;i>=1;i--)
   {
     CLK_SetLow();
     if(DATA&0x80)
         DIN_SetHigh();     
     else
         DIN_SetLow();
     R_BSP_SoftwareDelay(5, BSP_DELAY_UNITS_MICROSECONDS);   
     DATA=DATA<<1;
     CLK_SetHigh();
         R_BSP_SoftwareDelay(5, BSP_DELAY_UNITS_MICROSECONDS);
   }
}

向指定地址输出数据的函数为：

void Write_Max7219(char address,char dat)
{     
    CS_SetLow();
    Write_Max7219_byte(address);
    Write_Max7219_byte(dat);
    CS_SetHigh();
}

对点阵模块进行初始化的函数为：

void Init_MAX7219P(void)
{
   Write_Max7219(0x0b, 0x07);
   Write_Max7219(0x0c, 0x01);
   Write_Max7219(0x0f, 0x00);
}

由于是以点阵的方式输出显示内容，因此必须有字库的支持，其数据结构如下：

unsigned char disp[39][8]={
...
{0x8,0x14,0x22,0x3E,0x22,0x22,0x22,0x22},//A   10
{0x3C,0x22,0x22,0x3E,0x22,0x22,0x3C,0x0},//B
{0x3C,0x40,0x40,0x40,0x40,0x40,0x3C,0x0},//C
{0x7C,0x42,0x42,0x42,0x42,0x42,0x7C,0x0},//D
{0x7C,0x40,0x40,0x7C,0x40,0x40,0x40,0x7C},//E
{0x7C,0x40,0x40,0x7C,0x40,0x40,0x40,0x40},//F  15
{0x3C,0x40,0x40,0x40,0x40,0x44,0x44,0x3C},//G
{0x44,0x44,0x44,0x7C,0x44,0x44,0x44,0x44},//H
{0x7C,0x10,0x10,0x10,0x10,0x10,0x10,0x7C},//I
{0x3C,0x8,0x8,0x8,0x8,0x8,0x48,0x30},//J
{0x0,0x24,0x28,0x30,0x20,0x30,0x28,0x24},//K   20
{0x40,0x40,0x40,0x40,0x40,0x40,0x40,0x7C},//L
{0x81,0xC3,0xA5,0x99,0x81,0x81,0x81,0x81},//M
{0x0,0x42,0x62,0x52,0x4A,0x46,0x42,0x0},//N
{0x3C,0x42,0x42,0x42,0x42,0x42,0x42,0x3C},//O
{0x3C,0x22,0x22,0x22,0x3C,0x20,0x20,0x20},//P   25
{0x1C,0x22,0x22,0x22,0x22,0x26,0x22,0x1D},//Q
{0x3C,0x22,0x22,0x22,0x3C,0x24,0x22,0x21},//R
{0x0,0x1E,0x20,0x20,0x3E,0x2,0x2,0x3C},//S
{0x0,0x3E,0x8,0x8,0x8,0x8,0x8,0x8},//T
{0x42,0x42,0x42,0x42,0x42,0x42,0x22,0x1C},//U  30
{0x42,0x42,0x42,0x42,0x42,0x42,0x24,0x18},//V
{0x0,0x49,0x49,0x49,0x49,0x2A,0x1C,0x0},//W
{0x0,0x41,0x22,0x14,0x8,0x14,0x22,0x41},//X
{0x41,0x22,0x14,0x8,0x8,0x8,0x8,0x8},//Y
{0x0,0x7F,0x2,0x4,0x8,0x10,0x20,0x7F},//Z    35
...
{0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0},
};

实现显示要求的主程序为：

void hal_entry(void)
{
   char i,j,n,u;
   uint8_t ch[16]={17,10,25,38,25,34,38,23,14,32,38,34,14,10,27,38}; 
   unsigned int k;
   init_MAX7219();
   while(1)
   {
     for(j=0;j<16;j++)
     {
        n=ch[j];
        for(u=1;u<10;u++)
        {
          for(i=1;i<9;i++)
          {
             Write_Max7219(i,disp[n][i-1]);
          }
          R_BSP_SoftwareDelay(50, BSP_DELAY_UNITS_MILLISECONDS);
        }
     }
   }
}

经程序的编译及下载，其显示效果见图2所示，具体的动态显示效果见视频演示。

图2显示效果

 演示视频：

1.切换效果

https://www.bilibili.com/video/BV1oNiwBWER2/?vd_source=f302fc0cc3a0425328db53a3b92082ca

2. 移动效果

https://www.bilibili.com/video/BV1wYieBxEH2/?vd_source=a079e78685e1df6b254646e58442486e