hd7279.c

在51单片机上用7279芯片驱动键盘和数码管

#include <reg52.h>

void long_delay(void); 
void short_delay(void); 
void delay10ms(unsigned char); 
void write7279(unsigned char, unsigned char);	// 写入HD7279
unsigned char read7279(unsigned char);			// 读HD7279
void send_byte(unsigned char);        			//发送1个字节    
unsigned char receive_byte(void);     			//接受1个字节
unsigned char digit[5];               			//变量即I/O口定义
unsigned char key_number, j, k;
unsigned int tmr;
unsigned long wait_cnter;

sbit cs=P2^0; 	// 
sbit clk=P2^1; 	//
sbit dat=P2^2; 	//  
sbit key=P2^3; 	// 
//****** HD7279A ******
#define CMD_RESET 0xa4      //复位指令
#define CMD_TEST 0xbf       //测试指令
#define DECODE0 0x80        //方式0译码
#define DECODE1 0xc8        //方式1译码
#define CMD_READ 0x15       //读键盘指令
#define UNDECODE 0x90       //不译码指令
#define RTL_CYCLE 0xa3      //循环左移
#define RTR_CYCLE 0xa2      //循环右移
#define RTL_UNCYL 0xa1      //左移
#define RTR_UNCYL 0xa0      //右移
#define ACTCTL 0x98         //消隐
#define SEGON 0xe0          //段电亮
#define SEGOFF 0xc0         //闪烁控制
#define BLINKCTL 0x88
void main()
{
while (1)
 {
	
	
	   if (!key)                    //有键按下
	       {
				key_number=read7279(CMD_READ);//读出键码
				write7279(DECODE1+1,key_number/16);//第2位显示键码高8位
				write7279(DECODE1,key_number&0x0f);//第1位显示键码低 8位
				while (!key);                      //等待键码按下
				wait_cnter=0;
        	}
	   wait_cnter++;
	}
	//按键为0和超时进入下一步
	write7279(BLINKCTL,0xff);          // 消除闪烁       
	//快速计数

 }
//********************************************** 功能 子函数
void write7279(unsigned char cmd, unsigned char dta)
{
	send_byte (cmd);
	send_byte (dta);
}

unsigned char read7279(unsigned char command)
{
	send_byte(command);
	return(receive_byte());
}

void send_byte( unsigned char out_byte)
{
	unsigned char i;
	cs=0;
	long_delay();
	for (i=0;i<8;i++)
	 {
		if (out_byte&0x80)
			{
			   dat=1;
			}
		else
			{
			   dat=0;
			
			}
		clk=1;
		short_delay();
		clk=0;
		short_delay();
		out_byte=out_byte*2;
	}
	dat=0;
}
unsigned char receive_byte(void)
  {
	unsigned char i, in_byte;
	dat=1;                                  //设为输入状态
	long_delay();

	for (i=0;i<8;i++)
	{
		clk=1;
		short_delay();
		in_byte=in_byte*2;
		if (dat)
		{
			in_byte=in_byte|0x01;
		}
		clk=0;
		short_delay();
   }
	dat=0;
	return (in_byte);
 }

void long_delay(void)
{
	unsigned char i;
	for (i=0;i<0x30;i++);
	}
	    void short_delay(void)
	{
	unsigned char i;
	for (i=0;i<8;i++);
}
// ********************* 延时n*10ms **********************
void delay10ms(unsigned char time)
{
    unsigned char i;
    unsigned int j;
     for (i=0;i<time;i++)
     {
      for(j=0;j<0x390;j++)
      {
      if (!key)
       {
        key_int();
       }
      }
     }
}