求助SN74HC595级联应用，急急急

只看该作者 · 2015-6-4 18:40

两个SN74HC595级联控制数码管的程序
SRCLK和Rclk上升沿需要延时吗？
/*******74HC595发送数据******/
void Send_595(uchar dat) //发送一个字节
{
uchar i,j;
uchar m;

P_HC595_SRCLK = 0;
m = dat;
for(i=0; i<8; i++)
{
P_HC595_SRCLK = 0; //上升沿移位
if(m&0x80==0x80) P_HC595_SER = 1; //最高位D7开始直至最低位D0
else P_HC595_SER = 0;
P_HC595_SRCLK = 1;
m<<=1;
}

}
void send_595out() //595数据并出
{

P_HC595_RCLK = 0;
P_HC595_RCLK = 1;
}
主程序while(1)里面嵌入
{
Send_595(0x0f);
delay_ms(1);
Send_595(0xf0);
send_595out();
}
实际595发出的是0x01，程序哪里不对呢？

1万 · 2015-6-4 19:27

应该需要延时。你晶振多少兆？看看数据手册。

只看该作者 · 2015-6-4 19:29

void Send_595(unsigned char dat)
{
      unsigned char i;
      for(i=0;i<8;i++)
      {
         if(dat & 0x80)SER_595A = 1;
         else SER_595A = 0;

         dat <<= 1;
         SCLK_595 = 1;
         SCLK_595 = 0;
      }
}

void DisplayScan(void)
{
      switch(display_index)
      {
         case 0:
            Send_595(~4);
            Send_595(display_code[sec%10]);
            RCLK_595 = 0;
            RCLK_595 = 1;
            break;
         case 1:
            Send_595(~2);
            Send_595(display_code[sec/10]);
            RCLK_595 = 0;
            RCLK_595 = 1;
            break;
         case 2:
            Send_595(~8);
            Send_595(display_code[min%10]);
            RCLK_595 = 0;
            RCLK_595 = 1;
            break;
         case 3:
            Send_595(~16);
            Send_595(display_code[min/10]);
            RCLK_595 = 0;
            RCLK_595 = 1;
            break;
         case 4:
            Send_595(~64);
            Send_595(display_code[hour%10]);
            RCLK_595 = 0;
            RCLK_595 = 1;
            break;
         case 5:
            Send_595(~32);
            Send_595(display_code[hour/10]);
            RCLK_595 = 0;
            RCLK_595 = 1;
            break;
      }
      display_index++;
      if(display_index >= 6) display_index = 0;
}