LED点阵显示与编程

点阵的显示原理是行扫描列发送字码，或者是列扫描行发送字码。当点阵屏大于16×16时，普通的32个I/O口的 单片机 是无法直接连接了，必须通过串行输入/输出寄存器或者锁存器等I/O口扩展，例如锁存器：74HC373、74HC273等；串行输入并行输出寄存器：74HC595、74HC164等；I/O口扩展芯片：8255、8155等。

一、74HC273连接的16×16点阵示例

74HC273是8位数据/地址锁存器，D0～D7为数据出入端；Q0~Q7为数据输出端；WR为主清除端，低电平触发，将锁存数据清零；CLK是触发端，上升沿触发，即当CLK从低到高电平时，D0~D7的数据通过芯片输出到Q0~Q7，为0时将数据锁存。

74HC273的测试程序如下：

#include
sbit CLK=P3^0 ;
sbit MR=P3^1;
#define uchar unsigned char
#define uint unsigned int
//数码管字型表，对应0，1，2，3，4，5，6，7，8，9//
uchar Table[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
void Delay(uint i )        
{
   uchar j;
   for(;i!=0;i--)
      {for(j=200;j!=0;j--) ;}   
}

void main(void) 
{ 
uchar N;
MR=1;
while(1)
   { 
     for(N=0;N<10;N++)
       { 
        CLK=0;
        Delay(300);     //延时为了方便看到管脚电平变化
        P2=Table[N];
        CLK=1;
        Delay(300);
       }
     MR=!MR;
   } 
}
测试效果如下
利用74HC237连接的点阵如下图所示：
显示扫描方式也可以分为行扫描和列扫描，行扫描时，U1先输出行码依次扫描第1至第8行，同时U3输出第1行的左半部分列码，U4再输出第1行右半部分列码；扫描完1至8行后U2扫描8至16行，同时U3、U4输出对应的列码，这样就可以显示了。这仅仅是为了说明74HC273的连接图，不是最好的点阵连接方式，大家可以自己优化电路图。

二、74HC164与8255连接的点阵示例
    图中8255的PA、PB输出端应加上拉电阻（300Ω～1KΩ）。ULN2803为增加驱动列能力。
5288的地址：PA口为0000H、PB口为0100H、PK（控制）口为0300H。使用逐列扫描方式。
以显示四个静态的“欠一个吻”为例，参考程序如下：
#include
#includeCC.h>
#define PA8255 XBYTE[0X0000]
#define PB8255 XBYTE[0X0100]
#define PK8255 XBYTE[0X0300]
#define uhar unsigned char
uchar code Hzdot[]={
0x80,0x40,0x40,0x40,0x20,0x20,0x18,0x20,0x0F,0x10,0x0A,0x0C,0x08,0x03,0xE8,0x00,
0x08,0x03,0x08,0x0C,0x48,0x10,0x28,0x30,0x18,0x60,0x08,0x20,0x00,0x20,0x00,0x00,/*"欠",0*/
0x00,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,
0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0xC0,0x00,0x80,0x00,0x00,0x00,/*"一",1*/
0x00,0x00,0x80,0x00,0x80,0x00,0x40,0x00,0x20,0x00,0x10,0x00,0x0C,0x00,0xE3,0x7F,
0x04,0x00,0x08,0x00,0x10,0x00,0x20,0x00,0x60,0x00,0xC0,0x00,0x40,0x00,0x00,0x00,/*"个",2*/
0x00,0x00,0xFC,0x07,0x04,0x02,0x04,0x02,0xFC,0x03,0x40,0x48,0x30,0x44,0x0F,0x23,
0xCA,0x10,0x38,0x0C,0x08,0x03,0xF8,0x40,0x08,0x80,0x08,0x60,0xF8,0x1F,0x00,0x00/*"吻",3*/
};
uchar a,i,t,x[8]={0x7f,0xff,0xff,0xff,0xff,0xff,0xff,0xff};
char b;
void main(void)
{
PK8255=0X80;
while(1)
{
    for(a=0;a<64;a++)
   {
    PA8255=0x00;
    PB8255=0x00;
    for(b=7;b>=0;b--)
      {
    SBUF=~x[b];
    while(!TI) ;TI=0;
    }
    PA8255=hzdot[2*a];
    PB8255=hzdot[2*a+1];
    for(i=0;i<8;i++)
      {
    if((x[7]&0x01)==0) goto LP;
    if((~x[i]!=0)&&((x[i]&0x01)!=0))
       x[i]=x[i]<<7|x[i]>>1;
    else if((~x[i]!=0)&&((x[i]&0x01)==0))
       {
     x[i]=0xff;
     x[i+1]=0x7f;
     break;
     }
    }
   }
LP:x[0]=0x7f;x[7]=0xff;
}
}
三、74HC595连接的点阵示例
    很多点阵都是使用74HC595连接的，74HC595是8位串行输入/输出或者并行输出移位寄存器，具有高阻关断三态输出功能。 
   74HC595的功能表如下：

为了形象的演示74HC595的功能，编写如下测试程序：
#include
#define uint unsigned int
#define uchar unsigned char
sbit DS=P3^4;      //74HC595的数据串行输入端口
sbit ST=P3^7;      //74HC595并行输出使能
sbit SH=P3^6;      //74HC595移位寄存器移位使能
//测试串行传输数据：
uchar code Test[]={0xFF,0x00,0xAA,0xCC,0xEE,};
//******延时子程序******//
void delay(uint a)  
{
   uint i,j;
   for(i=0;i   for(j=0;j<4;j++);
}
void SendByte(uchar date)   
{
uchar i;
for(i=0;i<8;i++)
   {
SH=0;
ST=0;
if(date&0x80)   //将date最高位移到74HC595的移位寄存器
DS=1;
else
DS=0;
SH=1;     //SH上升沿时移位
ST=1;     //ST上升沿时输出数据
date=date<<1;   //左移一位，将送出第二位数据
delay(5000);
}
}
//****主函数****//
void main()
{
uchar i;
while(1)
    { 
for(i=0;i<5;i++) 
    SendByte(Test[i]); 
    }
}
测试是依次输出0xFF,0x00,0xAA,0xCC,0xEE几个数据，在点阵显示程序中，是将数据全部送到74HC595的移位寄存器，再同时显示出来，并不是像下图所示一个一个流动显示，这个仅仅是测试数据的传输路径。

  ORG 0000H
    LJMP STAR
    ORG 0BH
    LJMP INTT0
STAR: MOV 20H,#00H
       MOV A,#0FFH
    MOV R7,#0
    MOV P1,A
    MOV P2,A
    MOV P3,A
    MOV P0,A
    CLR P1.6
    MOV TMOD,#01H
    MOV TH0,#0FEH
    MOV TL0,#18H
    MOV SCON,#0
    MOV IE,#82H
    MOV SP,#70H
    MOV R0,#0
MAIN: LCALL DIS1
    MOV DPTR ,#TAB
    LCALL MOV DISP
    LJMP MAIN
MOV DISP:MOV B,#00H
DISLOOP: MOV R3,#07H
DIS MOV : JNB 02H,AAA
       DEC DPH
    CLR 02
AAA:   MOV R2,#0
       MOV R1,B
       SETB TR0
WAIT MOV :JBC 00H,DISMOV1
       AJMP WAIT MOV 
DIS MOV 1:DJNZ R3,DISMOV
       JNB 02H,BBB
    DEC DPH
    CLR 02
BBB:   INC B
       MOV A,B
    CJNE A,#0,CC1
    INC DPH
    INC R7
CC0:   INC B
       MOV A,B
    CJNE A,#0,CCC
    INC DPH
    INC R7
CC1:   INC B
       MOV A,B
       CJNE A,#0,CCC
    INC DPH
    INC R7
CCC:   MOV A,R1
MOV OUT:CJNE R7,#3,DISLOOP
       MOV A,B
    CJNE A,#24,DISLOOP
    MOV R7,#0
    RET
DIS1: MOV R3,#0AH
       CLR P1.3
    CLR P1.4
    CLR P1.5
DIS11: MOV R2,#0
       MOV DPTR,#TAB
    MOV R1,#0H
    SETB TR0
WAIT11:JBC 01H,DIS11
       AJMP WAIT11
DIS111:DJNZ R3,DIS11
       RET
INTT0: INC R0
       PUSH ACC
    MOV TH0,#0FEH
    MOV TL0,#18H
    JBC 00H,GOEND
    MOV A,R1
    MOV C A,@A+DPTR
    MOV SBUF,A
WAIT: JBC TI,GO
       AJMP WAIT
GO:    INC R1
       CJNE R1,#0,AA
    INC DPH
    SETB 02H
AA:    MOV A,R1
       MOV C A,@A+DPTR
    MOV SBUF,A
WAIT1: JBC TI,GO1
       AJMP WAIT1
GO1:   INC R1
       CJNE R1,#0,BB
    INC DPH
    SETB 02H
BB:    MOV A,R1
       MOV C A,@A+DPTR
    MOV SBUF,A
WAIT2: JBC TI,GO2
       AJMP WAIT2
GO2:   CLR P1.3
       CLR P1.4
    CLR P1.5
    NOP
    SETB P1.6
    NOP
    NOP
    NOP
    NOP
    NOP
    NOP
    NOP
    NOP
    NOP
    NOP
    NOP
    CLR P1.6
    MOV A,R2
    ANL A,#7H
    ANL P1,#0F8H
    ORL P1,A
P122: INC R2
       CJNE R2,#8,PAN1
    LJMP PAN1A
PAN1: JC PAN1A
       CJNE R2,#10H,PAN2
    LJMP PAN1B
PAN2: JC PAN1B
       CJNE R2,#018H,PAN3
    LJMP PAN1C
PAN3: JC PAN1C
       AJMP PANT
PAN1A: SETB P1.3
       AJMP PANT
PAN1B: SETB P1.4
       AJMP PANT
PAN1C: SETB P1.5
PANT: INC R1
       CJNE R1,#0,CC
    INC DPH
    SETB 02H
CC:    MOV A,R2
GO3:   CJNE R2,#24,GO4
    SETB 00H
GO4:   POP ACC
       RETI
GOEND: CLR TR0
       SETB 01H
    POP ACC
    RETI
    ORG 0A00H
TAB:   
;-- 逐行 顺向 --
DB 000H,000H,000H,003H,0C0H,000H,004H,030H,000H,004H,010H,000H,008H,03FH,0FCH,008H;
DB 000H,006H,010H,000H,002H,020H,000H,002H,020H,000H,002H,040H,083H,004H,041H,083H;
DB 004H,041H,083H,008H,042H,083H,008H,03FH,001H,0F0H,001H,001H,080H,002H,000H,0C0H;
DB 004H,000H,060H,008H,00CH,018H,030H,008H,004H,040H,01CH,002H,040H,026H,002H,040H;
DB 043H,002H,021H,080H,0C4H,03EH,000H,03CH;"欠",0
DB 000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H;
DB 000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,07FH,0FFH,0FCH,0C0H,000H;
DB 006H,080H,000H,002H,080H,000H,002H,080H,000H,002H,0C0H,000H,006H,07FH,0FFH,0FCH;
DB 000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H,000H;
DB 000H,000H,000H,000H,000H,000H,000H,000H;"一",1
DB 000H,000H,000H,000H,07CH,000H,000H,083H,000H,001H,000H,080H,006H,000H,060H,008H;
DB 000H,030H,030H,000H,00CH,040H,07EH,002H,080H,042H,001H,080H,082H,001H,081H,083H;
DB 081H,046H,082H,0E2H,078H,082H,01CH,000H,082H,000H,000H,082H,000H,000H,082H,000H;
DB 000H,082H,000H,000H,082H,000H,000H,082H,000H,000H,082H,000H,000H,082H,000H,000H;
DB 082H,000H,000H,082H,000H,000H,07CH,000H;"个",2
DB 000H,000H,000H,000H,01CH,000H,000H,022H,000H,07FH,0C1H,000H,0C0H,081H,0F8H,080H;
DB 080H,004H,080H,080H,002H,081H,000H,002H,08BH,000H,002H,08AH,002H,002H,08AH,022H;
DB 042H,089H,044H,042H,088H,0C4H,042H,088H,088H,042H,089H,008H,082H,082H,010H,082H;
DB 084H,020H,082H,084H,040H,082H,0C4H,083H,082H,07FH,084H,002H,001H,004H,004H,000H;
DB 084H,004H,000H,04CH,00CH,000H,033H,0F8H;"吻",3
……
END