regps.c

这是一个GPS接收模块的RMC数据提取代码 使用AVR作为CPU

//ICC-AVR application builder : 2008-2-22 10:46:36
// Target : M8
// Crystal: 7.3728Mhz
//2008/02/25
//DATA :201537,28.416216,N,115.567455,E,0.00,250208,

#include <iom8v.h>
#include <macros.h>
unsigned char rermc[70];
unsigned char crmc[10];
unsigned char new_drmc[50];

unsigned char rei2,cmi,cmi2,legn,datatrue,truei=1;

void port_init(void)
{
 PORTB = 0x00;
 DDRB  = 0x00;
 PORTC = 0x00; //m103 output only
 DDRC  = 0x00;
 PORTD = 0x00;
 DDRD  = 0x00;
}

void sendviwe(unsigned char x[],unsigned char i)
{unsigned char s;
for(s=0;s<i;s++)
{
 while ( !( UCSRA & (1<<UDRE)) );
 UDR=x[s];
 }
}

//UART0 initialize
// desired baud rate: 9600
// actual: baud rate:9600 (0.0%)
void uart0_init(void)
{
 UCSRB = 0x00; //disable while setting baud rate
 UCSRA = 0x00;
 UCSRC = BIT(URSEL) | 0x06;
 UBRRL = 0x2F; //set baud rate lo
 UBRRH = 0x00; //set baud rate hi
 UCSRB = 0x98;
}

#pragma interrupt_handler uart0_rx_isr:iv_USART0_RXC
void uart0_rx_isr(void)
{
 //uart has received a character in UDR
 unsigned char rei,yy;
 rei=UDR;
 if(truei) 
 {
   switch(rei)
   {
    case '$':
	cmi2=1;
	break;
	case 'G':
	if(cmi2) cmi2=2;
	break;
	case 'P':
	if(cmi2==2) cmi2=3;
	break;
	case 'R':
	if(cmi2==3) cmi2=4;
	break;
	case 'M':
	if(cmi2==4) cmi2=5;
	break;
	case 'C':
	if(cmi2==5) cmi2=6;		
	break;
	case ',':
	if(cmi2==6) cmi2=7;	
	break;	
   }    
    if(cmi2==7)  truei=0;//检测到RMC的头
 }
 else 
 {
   if(rei!=0x0a)  rermc[rei2++]=rei;//没到数据结尾，保存下来
   else //到数据结尾
   {
    	rei2=0;
    	truei=1;
    	cmi2=0;
   		cmi=1;    	
   }
 }
}

void jinwei_excharge(unsigned char i)//经纬度转化为正常读数
 { unsigned char t;
  if(i)
  {     
    t=crmc[4];
	crmc[4]=crmc[3];
	crmc[3]=crmc[2];
	crmc[2]=t;
  }
	else
	{
	 t=crmc[5];
	 crmc[5]=crmc[4];
	 crmc[4]=crmc[3];
	 crmc[3]=t;
	}
	
 }
 
void timecharge(void)  //change time to beijing time
 {
	     unsigned char x;
		 x=crmc[0]-0x30;
	    if(x>0) x=x*10;		 
		 x=x+(crmc[1]-0x30);
		 x=x+0x08;		 
		 crmc[0]=x/10+0x30;		 
		 crmc[1]=x%10+0x30;	     
 }
 
void getdata(unsigned char sx)//
{ unsigned char sss,ssx=0,lsx; 
 lsx=sx+11;
 for(;sx<lsx;sx++)
 {
  sss=rermc[sx];
  if(sss==',')  break; 
  crmc[ssx]=sss;
  ssx++;  
 }  
 legn=sx;
}

void newrmc()
{
 unsigned char wx,cx=0,lwx,llwx; 
 getdata(0);//get time 
 timecharge();//
 for(wx=0;wx<6;wx++)
 { 
 new_drmc[wx]=crmc[wx];
 }
 new_drmc[wx]=',';//real time 
 
 getdata(legn+1);//get data true
 if(crmc[0]=='A') datatrue=1;
 else datatrue=0; 
 
 getdata(legn+1);//get 纬度  
 jinwei_excharge(1);
 wx=wx+1;
 lwx=wx+9;
 for(;wx<lwx;wx++)
 { 
 new_drmc[wx]=crmc[cx];
 cx++;
 } 
 new_drmc[wx]=',';//
 
 getdata(legn+1);//n/s
 new_drmc[wx+1]=crmc[0];// 
 new_drmc[wx+2]=',';//
 
 getdata(legn+1);//get jingdu
 jinwei_excharge(0);
 cx=0;
 wx=wx+3;
 lwx=wx+10;
 for(;wx<lwx;wx++)
 { 
 new_drmc[wx]=crmc[cx];
 cx++;
 }
 new_drmc[wx]=',';//
 
 getdata(legn+1);//w/e
 new_drmc[wx+1]=crmc[0];//
 new_drmc[wx+2]=',';//
 
 llwx=legn+1;//save 
 getdata(legn+1);//speed地面速率
 cx=0;
 wx=wx+3;
 lwx=legn-llwx+wx;//速度有效长度
 for(;wx<lwx;wx++)
 { 
 new_drmc[wx]=crmc[cx];
 cx++;
 }
 new_drmc[wx]=',';//
 
 getdata(legn+1);//地面航向
 getdata(legn+1);//date
 cx=0;
 wx=wx+1;
 lwx=wx+6;
 for(;wx<lwx;wx++)
 { 
 new_drmc[wx]=crmc[cx];
 cx++;
 }
 //new_drmc[wx]=',';//
 new_drmc[wx]=0x0a;//
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 uart0_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x00; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}


void main(void)
{
 init_devices();
 while(1)
 {
 if(cmi)
 {  
  CLI();  
  newrmc();
  sendviwe(new_drmc,legn-5);
  SEI();
  cmi=0;
 }
 }
}