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code:interrupt_driven_tsip

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code:interrupt_driven_tsip [2008/07/12 13:04] – laurencebcode:interrupt_driven_tsip [2008/10/11 11:28] (current) – laurenceb
Line 2: Line 2:
 //global(s) //global(s)
 extern gps_type Gps; extern gps_type Gps;
 + 
 // Interrupt driven TSIP (lassen iq) parser for Atmel AVR (state machine based) // Interrupt driven TSIP (lassen iq) parser for Atmel AVR (state machine based)
 + 
 #define ETX 0x03 //as defined in TSIP specs #define ETX 0x03 //as defined in TSIP specs
 #define DLE 0x10 #define DLE 0x10
-  
-//8O1 send routine for initial setup 
  
-void suart_send(char c)+//8O1 send routine for initial setup 
 +  
 +int suart_send(char c)
 { {
  u08 n;  u08 n;
- u08 p=FALSE; + u08 p=FALSE; //odd parity 
- clear; //start bit+ CLEAR; //start bit
  delay;  delay;
  for(n=0;n<8;n++) //the data  for(n=0;n<8;n++) //the data
Line 20: Line 20:
  if(c & 0x01)  if(c & 0x01)
  {  {
- set; //update parity+ SET; //update parity
  p=!p;  p=!p;
  }  }
  else  else
  {  {
- clear;+ CLEAR;
  }  }
- c>>1;+ c>>=1;
  delay;  delay;
  }  }
  if(p) //the parity  if(p) //the parity
  {  {
- set;+ SET;
  }  }
  else  else
  {  {
- clear;+ CLEAR;
  }  }
  delay;  delay;
- set; //stop bit+ SET; //stop bit
  delay;  delay;
 + return 0;
 } }
 + 
 ISR(USART_RX_vect) //UART interrupt on mega xx8 series ISR(USART_RX_vect) //UART interrupt on mega xx8 series
 { {
Line 48: Line 49:
  static u08 placemarker;  static u08 placemarker;
  static gps_type gps;  static gps_type gps;
- static u08 *d; + static u08 state; //state machine 
- //static u08 state; //state machine+ u08 *d=(u08*)&gps; //points to our data
  if(UCSR0A & (BV(FE0)|BV(UPE0))) //a framing or parity error causes us to drop the packet  if(UCSR0A & (BV(FE0)|BV(UPE0))) //a framing or parity error causes us to drop the packet
  {  {
Line 55: Line 56:
  }  }
  char c=UDR0;  char c=UDR0;
- if(state==2 || state==4) //the two states where we can write something+ if(state==2 || state==4) //the two states where we can write something
  {  {
- if(!placemarker && id==0x6D) //the status byte+ if(!placemarker && id==0x6D) //start of packet - the status byte
  {  {
- gps.status= c & 0x07; //number from 0 to 7, 0=undefined, 7=ground station,4 3D+ gps.status= c & 0x0F; //number from 0 to 7, 0=undefined, 7=ground station,4 3D
  gps.nosats=(c & 0xF0)>>4; //number of tracked satellites  gps.nosats=(c & 0xF0)>>4; //number of tracked satellites
  }  }
- else if(id==0x4A && placemarker<16) //lla packet+ else if(id==0x4A) //lla(time) packet - 4 floats
  {  {
- if(!placemarker)+ if(placemarker<12) //lla
  {  {
- d=&gps.latitude;+ d[27-placemarker]=c;
  }  }
- d[placemarker]=c; + if(placemarker>15 && placemarker<20) //time
- } +
- else if(id==0x56 && placemarker<12) //venu packet +
- { +
- if(!placemarker)+
  {  {
- d=&gps.veast;+ d[31-placemarker]=c; //time of fix
  }  }
- d[placemarker]=c;+ } 
 + else if(id==0x56 && placemarker<12)  //enu packet - 3 floats 
 + { 
 + d[11-placemarker]=c;
  }  }
  else if(placemarker>27) //max 7 floats  else if(placemarker>27) //max 7 floats
  {  {
- state=0; //we had too much data, something is wrong+ state=0; //we had too much data, something is wrong
  }  }
  placemarker++; //incr placeholder  placemarker++; //incr placeholder
  }  }
- switch(state)+ switch(state) //run the state machine
  {  {
  case 0:  case 0:
Line 99: Line 99:
  id=c;  id=c;
  }  }
- else //unknown or not something we are interested in+ else //unknown or not something we are interested in
  {  {
  state=0;  state=0;
Line 113: Line 113:
  if(c==ETX)  if(c==ETX)
  {  {
- toggle_pin; //toggles pin D5 - flashing LED tells us gps is working + state=0; //end of packet - we arent in one 
- if(!Gps.packetflag) //main has unlocked the data+ if(id==0x6D) //the 0x6D packet is sent after a fix calculation or at 1Hz
  {  {
- Gps=gps; //copy into the global variable + gps.packetflag=TRUE;//TRUE==1 
- Gps.packetflag=TRUE; //this is usually the last interesting part of the fix info to come through + toggle_pin; //toggles pin D5 - flashing LED tells us gps is working 
- state=0; //dont need to run again+ if(!Gps.packetflag) //main has unlocked the data 
 + { 
 + Gps=gps; //copy into the global variable 
 + }
  }  }
  }  }
Line 125: Line 128:
  state=4;  state=4;
  }  }
- else //this shouldnt happen+ else //this shouldnt happen
  {  {
  state=0;  state=0;
Line 131: Line 134:
  break;  break;
  case 4:  case 4:
- if(c==ETX || c==DLE) //state 4 shouldnt get either of these+ if(c==ETX || c==DLE) //state 4 shouldnt get either of these
  {  {
  state=0;  state=0;
  }  }
  break;  break;
- default: //something wrong, go to 0+ default: //something wrong, go to 0
  state=0;  state=0;
  }  }
-} +}</code>
-</code>+
code/interrupt_driven_tsip.1215867892.txt.gz · Last modified: 2008/07/19 23:31 (external edit)
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