m48_2.i

这是基本的485通讯实例希望对大家有用。C语言编写用户可根据自己的情况修改相应的传输速率。

// CodeVisionAVR C Compiler
// (C) 1998-2004 Pavel Haiduc, HP InfoTech S.R.L.

// I/O registers definitions for the ATmega48(V)


#pragma used+
sfrb PINB=3;
sfrb DDRB=4;
sfrb PORTB=5;
sfrb PINC=6;
sfrb DDRC=7;
sfrb PORTC=8;
sfrb PIND=9;
sfrb DDRD=0xa;
sfrb PORTD=0xb;
sfrb TIFR0=0x15;
sfrb TIFR1=0x16;
sfrb TIFR2=0x17;
sfrb PCIFR=0x1b;
sfrb EIFR=0x1c;
sfrb EIMSK=0x1d;
sfrb GPIOR0=0x1e;
sfrb EECR=0x1f;
sfrb EEDR=0x20;
sfrb EEARL=0x21;
sfrb EEARH=0x22;
sfrw EEAR=0x21;   // 16 bit access
sfrb GTCCR=0x23;
sfrb TCCR0A=0x24;
sfrb TCCR0B=0x25;
sfrb TCNT0=0x26;
sfrb OCR0A=0x27;
sfrb OCR0B=0x28;
sfrb GPIOR1=0x2a;
sfrb GPIOR2=0x2b;
sfrb SPCR=0x2c;
sfrb SPSR=0x2d;
sfrb SPDR=0x2e;
sfrb ACSR=0x30;
sfrb MONDR=0x31;
sfrb SMCR=0x33;
sfrb MCUSR=0x34;
sfrb MCUCR=0x35;
sfrb SPMCSR=0x37;
sfrb SPL=0x3d;
sfrb SPH=0x3e;
sfrb SREG=0x3f;
#pragma used-


// Interrupt vectors definitions



// CodeVisionAVR C Compiler
// (C) 1998-2000 Pavel Haiduc, HP InfoTech S.R.L.


#pragma used+

void delay_us(unsigned int n);
void delay_ms(unsigned int n);

#pragma used-

//波特率9600/9个数据位/1个停止位/奇校验/收发开启/接收中断
void USARTinit(void)
void USARTinit(void)
     {  
       (*(unsigned char *) 0xc1)=0x9C;
       (*(unsigned char *) 0xc2)=0x36;
       (*(unsigned char *) 0xc4)=0x2F;
       PORTD.4=0;                      //MAX485平时工作在接收状态
       DDRD.4=1;
     } 

//-----------------------------------------------------------
//从数组datas[]的首地址开始发送amount个数据,其中第0个数据是地址帧,其他是数据帧
void TXD(unsigned char *datas)
     {
       unsigned char i=0;  
       PORTD.4=1;                      //使MAX485处于发送状态
       while(i<10    )                 //一共发送amount个数据
            {  
              if(i==0) (*(unsigned char *) 0xc1)|=1; else (*(unsigned char *) 0xc1)&=254;   
              (*(unsigned char *) 0xc6)=*(datas+i);         //装载数据开始发送 
              while(((*(unsigned char *) 0xc0)&64)==0);   //等待发送结束
              (*(unsigned char *) 0xc0)|=64;              //清除发送结束标志
              i++;                     //发送次数统计
            } 
       PORTD.4=0;                      //使MAX485处于接收状态
     }   
/*
  CodeVisionAVR C Compiler
  (C) 1998-2000 Pavel Haiduc, HP InfoTech S.R.L.

  Prototypes for Dallas Semiconductor
  1 Wire protocol functions

  BEFORE #include -ING THIS FILE YOU
  MUST DECLARE THE I/O ADDRESS OF THE
  DATA REGISTER OF THE PORT AT WHICH
  THE 1 WIRE BUS IS CONNECTED AND
  THE DATA BIT USED

  EXAMPLE FOR PORTB:

    #asm
        .equ __w1_port=0x18
        .equ __w1_bit=3
    #endasm
    #include <1wire.h>
*/


#pragma used+
unsigned char w1_init(void);
unsigned char w1_read(void);
unsigned char w1_write(unsigned char data);
unsigned char w1_search(unsigned char cmd,void *p);
unsigned char w1_dow_crc8(void *p,unsigned char n);
#pragma used-



unsigned char  send[10    ];               //发件箱
unsigned char inbox[10    ];               //收件箱
unsigned char n=0;                         //记忆中断次数

//--------------------------------------------------------------------
interrupt[19] Rxd_isr(void)                //接收中断
{  
  unsigned char ERROR=0; 
  if( (*(unsigned char *) 0xc0)&4 || (*(unsigned char *) 0xc0)&16 ) ERROR=1;     //记录奇偶效验错误或者帧错误 
  inbox[n]=(*(unsigned char *) 0xc6);                           //把接收到的数据保存到收件箱
  n++;                                     //记忆接收的次数
  if(ERROR)                                //如果通讯有错....
    {
      n=0;                                 //接收计数清0 
      inbox[0]=0;                          //把地址改为无效地址0
      (*(unsigned char *) 0xc0)|=0x01;                        //重新打开接收器的地址帧筛选功能
    } 
  
  //如果地址匹配本机或者是广播地址就关闭地址筛选(多机通讯)功能  
  if(inbox[0]==2     ||inbox[0]==255) (*(unsigned char *) 0xc0)&=254; 
  
  if(n==10    )                            //接收到amount个数据以后...
    {  
      n=0;                                 //接收计数清0 
      (*(unsigned char *) 0xc0)|=0x01;                        //重新打开接收器的地址帧筛选功能
      if(inbox[10    -1]==w1_dow_crc8(inbox,10    -1))   //如果crc8校验正确就...
        {   
          if(inbox[0]==2    )            //如果地址匹配本机就回复数据
            {  
              send[0]=1;                   //发件箱地址指向主机
              send[10    -1]=w1_dow_crc8(send,10    -1); //产生发件箱的crc8校验码
              TXD(send);                   //发送发件箱的数据包send[] 
              //请在这里备份你的收件箱信息
            }
          if(inbox[0]==255)                //如果是广播地址就...
            {
              //请在这里添加你的代码
              //收到广播数据请不要回复
            }
        }
    }
} 

//---------------------------------------------------------------------
void main(void)
{ 
  USARTinit();                             //串口初始化
  (*(unsigned char *) 0xc0)=0x01;                             //从机打开地址帧筛选功能(多机通讯模式)
  #asm("sei")                              //打开全局中断 
  while(1)
  {  
    //请在这里添加你的代码        
  }
}   //end