gpscode.c

GPS read and write,retrieve time,loction from gps

                                            }
                                         else
                                            {
                                            commandpos=11;
                                            GPSoutdata=1;
                                            shiftout.h.b1=34;
                                            shiftout.h.b2=GPSdata[0];
                                            shiftout.h.b3=GPSdata[1];
                                            shiftout.h.b4=GPSdata[2];
                                            outpos=3;
                                            incnt=32;
                                            header4=0;
                                            }
                                         break;
                     default:            shiftout.h.b1=0xff;
                                         incnt=8;    
                                         break;            
                     }
                  }
               break;
       case 4 : --incnt;                 // count data for other address
               if (!incnt)
                  {
                  --bytecnt;
                  incnt=8;
                  if (!bytecnt)
                     commandpos=5;
                  }
               break;
      case 5 : bytecnt <<= 1;          // reading in byte count for reply
               bytecntlow = bithold;
               --incnt;
               if (!incnt)
                  {
                  incnt=8;
                  if ((!bytecnt) || (bytecnt == 0xff))
                     commandpos=0;
                  else
                     commandpos=6;
                  }
               break;
      case 6 : --incnt;             // count data for reply
               if (!incnt)
                  {
                  --bytecnt;
                  incnt=8;
                  if (!bytecnt)
                     commandpos=0;
                  }
               break;
      case 11: --incnt;
               if (!incnt)
                  {
                  if (outpos<29)
                     {
                     incnt=32;
                     shiftout.h.b1=GPSdata[outpos];
                     ++outpos;
                     shiftout.h.b2=GPSdata[outpos];
                     ++outpos;
                     shiftout.h.b3=GPSdata[outpos];
                     ++outpos;
                     shiftout.h.b4=GPSdata[outpos];
                     ++outpos;
                     }
                  else
                     {
                     incnt=24;
                     shiftout.h.b1=GPSdata[outpos];
                     shiftout.h.b2=timecnt.h.b1;
                     shiftout.h.b3=timecnt.h.b2;
                     ++commandpos;
                     }
                  }
               break;
      case 12: --incnt;
               if (!incnt)
                  {
                  incnt=8;
                  commandpos=0;
                  GPSoutdata=0;
                  }
               break;
        }
   IE1=0;
   IE0=0;
   EX0=0;
   EX1=1;
   }
//testbit1=0;
}

void ClockInactiveHandler() interrupt 2  using 1
{
//testbit2=1;
if ((lastedge) && (BIT_CLKP))
   {
   lastedge=0;
   Datain=1;
   outcnt=0; 
   if (senddata)
      {
      if (!commandpos)
         {
         BIT_DTAPIC=1;
         senddata=FALSE;
         }
      else
      	{
   	   if (shiftout.h.b1 & 0x80)
         	BIT_DTAPIC=1;
	      else
	         BIT_DTAPIC=0;
   	   shiftout.w<<=1;
	   	}
      }
   IE1=0;
   IE0=0;
   EX1=0;
   EX0=1;
   }
//testbit2=0;
}

void TimerInt() interrupt 1  using 3         // every 1/16 milliseconds
{
++timecnt.w;
++outcnt;
}

void SerialInt() interrupt 4  using 2
{
unsigned char TempChar;

//testbit4=1;
if ( RI )                                 // if a character was received:
   {
   //serialbit ^= 1;
   TempChar = SBUF;                       // get the character from the serial buffer
   RI = 0;                                // reset to allow another character to be received
   if (!GPSoutdata)
      {
      if (instring)
         {
         if (lookGPRMCLong)
            {
            if ((inserialcnt==8) || (inserialcnt==20) || (inserialcnt==33) || ((inserialcnt >= 1) && (inserialcnt <= 6)) || ((inserialcnt >= 10) && (inserialcnt <= 13)) || ((inserialcnt >= 15) && (inserialcnt <= 18)) || ((inserialcnt >= 22) && (inserialcnt <= 26)) || ((inserialcnt >= 28) && (inserialcnt <= 31)) || ((inserialcnt >= 47) && (inserialcnt <= 52)))
               {
               GPSdata[savecnt]=TempChar;
               ++savecnt;
               if (savecnt >= 32)
                  {
                  instring=0;
                  header4=0;
                  timecnt.w=0;
                  }
               }
            ++inserialcnt;
            }
         else if (lookGPRMCShort)
            {
            if (inserialcnt)
               {
               GPSdata[savecnt]=TempChar;
               ++savecnt;
               if (savecnt >= 32)
                  {
                  instring=0;
                  header4=0;
                  timecnt.w=0;
                  }
               }
            ++inserialcnt;
            }      
         else
            {
            if (inserialcnt >= 32)
               {
               GPSdata[savecnt]=TempChar;
               ++savecnt;
               if (savecnt >= 32)
                  {
                  instring=0;
                  header4=0;
                  timecnt.w=0;
                  }
               }
            ++inserialcnt;
            }      
         }
      else
         {
         header0=header1;
         header1=header2;
         header2=header3;
         header3=header4;
         header4=TempChar;
         if (lookGPRMCLong || lookGPRMCShort)
            {
            if ((header0=='G') && (header1=='P') && (header2=='R') && (header3=='M') && (header4=='C'))
               {
               instring=1;
               inserialcnt=0;
               savecnt=0;
               }
            }
         else if (lookGPGGA)
            {
            if ((header0=='G') && (header1=='P') && (header2=='G') && (header3=='G') && (header4=='A'))
               {
               instring=1;
               inserialcnt=0;
               savecnt=0;
               }
            }
         }
      }
   }
else
   {
   TI=0;
   switch (nextout)
      {
      case 4: SBUF='C';
              --nextout;
              break;
      case 3: SBUF='D';
              --nextout;
              break;
      case 2: SBUF=0x0a;
              --nextout;
              break;
      case 1: SBUF=0x0d;
              --nextout;
              break;
      }
   }
}