usb.c

老外开发的机器人的底层单片机代码。比较有参考价值哦！

    //Generate message
	buffout.Int[0]  = 0xFFA5;			 		 //Start word 
	buffout.Int[1]  = 0; 		     	 		 //provis for diff message types
	buffout.Int[2]  = 0;			 	 		 //spare
	buffout.Int[3]  = Word((char*)&time);	  	 //sequence number
    buffout.Int[4]  = Word((char*)&Analog0);	 //Analog inputs (IR 0 - 7)
	buffout.Int[5]  = Word((char*)&Analog1);	  
    buffout.Int[6]  = Word((char*)&Analog2);
	buffout.Int[7]  = Word((char*)&Analog3);	  
    buffout.Int[8]  = Word((char*)&Analog4);
	buffout.Int[9]  = Word((char*)&Analog5);	  
    buffout.Int[10] = Word((char*)&Analog6);
	buffout.Int[11] = Word((char*)&Analog7);	  
	buffout.Int[12] = Word((char*)&Analog8);	 // battery voltage  
    buffout.Int[13] = Word((char*)&Analog9);	 // no connection
	buffout.Int[14] = Word((char*)&Analog10);	 // no connection	  
    buffout.Int[15] = Word((char*)&Analog11);	 // no connection
	buffout.Int[16] = Word((char*)&Analog12);	 // no connection  
    buffout.Int[17] = Word((char*)&RC_Sonar[0]); // timer values or est. RC posn.
	buffout.Int[18] = Word((char*)&RC_Sonar[1]); // RC servo position(deg*10) 
    buffout.Int[19] = Word((char*)&RC_Sonar[2]); //     or sonar distance(mm)
	buffout.Int[20] = Word((char*)&RC_Sonar[3]);	  
    buffout.Int[21] = Word((char*)&RC_Sonar[4]);
	buffout.Int[22] = Word((char*)&RC_Sonar[5]);  
    buffout.Int[23] = Word((char*)&RC_Sonar[6]);
	buffout.Int[24] = Word((char*)&PitchDeg);	 //pitch attitude in deg *10  
    buffout.Int[25] = Word((char*)&RollDeg);     //roll attitude in deg *10
	buffout.Int[26] = Word((char*)&AccelX);	  	 //accel forward (mm/sec^2)
    buffout.Int[27] = Word((char*)&AccelY);		 //accel sideways (mm/sec^2)
	buffout.Int[28] = Word((char*)&YRatedps);  	 //yaw rate in deg/sec *10	  
    buffout.Int[29] = Word((char*)&hdgdeg);		 //inertial hdg deg*10 (+/- 180)
	buffout.Int[30] = Word((char*)&Compass);	 //mag hdg in deg*10 (0 - 359.9)
    buffout.Int[31] = Word((char*)&headingDR);	 //heading based on encoders
	buffout.Long[16] = Long((char*)&DistActL);   //Distance of L wheel travel (mm)			
	buffout.Long[17] = Long((char*)&DistActR); 	 //Distance of R wheel travel (mm)  
    buffout.Int[36] = Word((char*)&SpeedL); 	 //left wheel speed (mm/sec)
	buffout.Int[37] = Word((char*)&SpeedR);	  	 //right wheel speed (mm/sec)
    buffout.Int[38] = Word((char*)&DIOdata);			 		 //discrete i/o status
	buffout.Int[39] = 0;	  		 	 		 //spare	  
    buffout.Int[40] = 0;			 	 		 //spare
	buffout.Int[41] = 0;	  	 		 		 //spare
    buffout.Long[21] = Long((char*)&Xcoord);	 //X coordinate
    buffout.Long[22] = Long((char*)&Ycoord);	 //Y coordinate
    buffout.Int[46] = 0;	   			 		 //spare
	buffout.Int[47] = 0;				 		 //spare  
    buffout.Int[48] = 0;				 		 //spare
	buffout.Int[49] = 0;				 		 //spare	     
    buffout.Int[50] = 0;				 		 //spare         
	buffout.Int[51] = 0;				 		 //spare	  		
    buffout.Int[52] = 0;				 		 //spare			
	buffout.Int[53] = 0;				 		 //spare  	  	   
    buffout.Int[54] = 0;				 		 //spare			 
	buffout.Int[55] = Word((char*)&ucStatus); 	 //status message 		
    buffout.Int[56] = 0;				 		 //spare
	buffout.Int[57] = Word((char*)&FwdCmdCurrent);	//Forward command in progress
    buffout.Int[58] = Word((char*)&FwdModeDone);	//Status of current fwd cmd
    buffout.Int[59] = Word((char*)&TurnCmdCurrent);	//Turn command in progress 				
	buffout.Int[60] = Word((char*)&TurnModeDone);	//Status of current turn cmd 			 
	buffout.Int[61] = Word((char*)&seqnumCurrent);  //Seqnum of last message rec'd			 

    //calculate CRC16  (for buffout[0] through buffout[BUFFSIZEout-1])
	buffptr = (char*) buffout.Int;
	CRC16 = 0;
	for(i=0;i<((BUFFSIZEout-1)*2);i++) 
	  {  CRC16 = addCRC(CRC16,*buffptr++);
	  }
	buffout.Int[62] = CRC16;
	
	USBsendidx = 0;	  //set indicating message ready to be sent
  }	
  
//--------------------------------------------------------------------------
void USBsendmsg()     //transmit contents of buffout
/*  Transfers contents of buffout to USB module using emulated parallel port.
	This function is non-blocking, but requires the calling code to control 
	the USBsendidx pointer and generate multiple calls if necessary.
*/
  {	 DDRB = 0xFF;		 //set data port as output
     buffptr = (char*) buffout.Int;
     while(USBsendidx < BUFFSIZEout*2)    		
       {
	    if(PORTA & 0x04) return;  		 //return if transmit buffer full
		    PORTA |= 0x02;	 		 	 //WR strobe on		
			PORTB = *buffptr++; 		 //send output data to port
			PORTA &= ~0x02; 		 	 //WR strobe off
			USBsendidx +=1;	
       }
  }
  
//--------------------------------------------------------------------------
void USBreadmsg()		
/* Reads data from USB module until buffer is full through emulated parallel
   port.  This function is non blocking.
*/
  {    
	 char chr;
	 
	 DDRB = 0x00;	             //set data port as input
     while(USBreadidx < BUFFSIZEin*2)    			 //read all bytes
	   {
	   	if(USBreadidx == 0)
		  { 
		    do		  	 //read bytes til find start byte "FF"
		      { 
			    if(PORTA & 0x08) return;	 //return if receive buffer empty
	   		  	PORTA &= ~0x01;   			 //RD strobe on
	 		  	chr = PORTB;	 			 //get data byte
	 		  	PORTA |=  0x01;				 //RD strobe off
			  } while (chr != 0xFF);
//check for 2nd start byte????
		   USBreadidx = 1;
	      }	
		  	//read next 123 bytes
	        if(PORTA & 0x08)  return;	 //return if buffer empty
	   		PORTA &= ~0x01;   			 //RD strobe on
	 		buffin[USBreadidx] = PORTB;	 //get data byte
	 		PORTA |=  0x01;				 //RD strobe off
			USBreadidx += 1;
	   }		
}
  
//---------------------------------------------------------------------------
void USBupdate(void)
  {
     int i;    			   	   			   //loop counter
//Send output message
	if(time%4 == 0)          //if time for a new output message (every 64 msec.)
	  { 
	    if(USBsendidx == BUFFSIZEout*2)   //if last message was sent
		  { USBmsgfill();			   	  //load buffer with new data
			USBsendidx = 0;			   	  //set index to first byte
	      }
		else
		  { //if(BiteMode == 0)printf("USB output message missed\n");
	      }		  		
      }
	if(USBsendidx != BUFFSIZEout*2)	   //if message not fully sent
	  { USBsendmsg();
      }		
	    
//Read input message
	USBtimeout += 1; 				   //increment timeout counter each frame
	if(USBtimeout >= USBtimeoutLimit) USBtimeout = USBtimeoutLimit;
	
	if(USBreadidx < BUFFSIZEin*2) USBreadmsg();  //if buffer not full, read more
	if(USBreadidx == BUFFSIZEin*2)               //if buffer is full
	  { for(i=1; i<BUFFSIZEin*2; i++)				 //transfer data for export
	     { BuffIn[i] = buffin[i];
		 } 
		seqnumUSB = Word(&BuffIn[2]);			  	 
		USBreadidx = 0;							 //reset to buffer empty  

		USBtimeout -= 12;				//decrement timeout counter when receive
		if(USBtimeout <=0) USBtimeout = 0;		
	  }	
	  
  }  //end USBupdate()	

//  OPEN SOURCE SOFTWARE LICENSE
/* Permission is hereby granted, free of charge, to any person obtaining a copy 
of this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to use, 
copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the 
Software, and to permit persons to whom the Software is furnished to do so, 
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all 
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS 
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR 
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER 
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/