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ATmega8---SPI bus control

Publisher:温暖心绪Latest update time:2015-09-10 Source: eefocusKeywords：ATmega8 Reading articles on mobile phones Scan QR code
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During development, the ATmega8 peripheral SPI bus is used:
Before sending data, it is in slave mode and in receiving state. When sending, it needs to enter master mode, and then enter slave mode after completing the sending.
The following are the operation functions:

interrupt [SPI_STC] void spi_interrupt(void)
{
//uchar tmp;
uchar i,b; 
    
//tmp=SPSR;
b=SPDR; 
    
r_buf[0]=r_buf[1];
r_buf[1]=r_buf[2];
r_buf[2]=r_buf[3];
r_buf[3]=r_buf[4];
r_buf[4]=r_buf[5];
r_buf[5]=b;
    if((r_buf[0]==0xff)&&(r_buf[5]==0xaa))
    {
  r_full=1;
r_data[0]=r_buf[0];
r_data[1]=r_buf[1];
r_data[2]=r_buf[2];
r_data[3]=r_buf[3];
r_data[4]=r_buf[4];
r_data[5]=r_buf[5];
}
    if(r_full)
    {  
        r_full=0;
        if(r_data[1]!=99)return;
        switch(r_data[2])
        {
          case 3: 
          case 0x31:
                if((r_data[4]>16)||(r_data[3]>16))return;
                if(r_data[3]==0)return;
                else if(r_data[4]==0)
                {  
                    for(i=0;i<16;i++)
                    {
                        tmp_ddc[i]=r_data[3];
                    }                     
                }
                else
                {  
                    tmp_ddc[r_data[4]-1]=r_data[3];
                }
                break;  
          default: 
                break;
        }
    }
}
 
//------------------------------------------------ -
void spi_init_s()           //Before there is any communication, it is in slave mode
{
  DDRB.4=1;
  DDRB.2=0;
  PORTB.2=1;
  DDRB.3=0;
  DDRB.5=0;
  SPCR=0XC0;
}
 
void spi_init_m()
{
  DDRB.4=0;
  DDRB.2=1;
  DDRB.3=1;
  DDRB.5=1; 
    
    SPCR=0x52;
SPSR=0X01;
}
 
//-------------------------------------
void send_spi()
{   
uchar i;   
    
while(PINB.2==0){;}
    
spi_init_m(); 
    
  #asm("cli") 
    
PORTB.2=0;
delay_ms(1);
    
  for(i=0;i<2;i++)
  {       
  SPDR=video_new[i];   
        
   #asm("wdr")  
        
  while((SPSR&0X80)!=0X80);
  } 
    
  delay_ms(10);                             
  PORTB.2=1;
  #asm("sei") 
    
  spi_init_s();
}

Keywords：ATmega8 Reference address：ATmega8---SPI bus control

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