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！

///  USB bus    USB.c					// Rev 9/1/05

//Copyright (C) 2005 Alex Brown	[e-mail]
//This program is free software; See license at the end of this file for details.

/*
external functions:
    USBupdate();   	    //handles sending and receiving USB messages
	USBinit();   		//initializes 9S12 to drive FTDI chip
    Long(char*);   		//convert between VC++ & ICC12 long and word(int)formats
    Word(char*);	    //    (reverses bytes)
	
local functions:	
	USBmsgfill(); 		//loads transmit message with data
	USBsendbuff();		//transmits a 62 byte message
	USBreadbuff(); 		//reads a 62 byte message
	
This version sends 124 byte messages over USB bus to a PC and receives 124 bytes
using the FTDI parallel to USB chip.

Both sendbuff and readbuff are non-blocking.  They return if the buffer is full
(or empty) and can complete the transaction in subsequent cycles.

transmit parallel transfers in 130 usec.  (9S12DP256 @ 24 Mhz)

Note: as an annoyance,  ICC12 and VC++ store integer variables in opposite byte 
order.  Hence, the functions Word() and Long() are created to swap bytes.  This
program swaps both directions so VC++ requires no compensations.

*/

#include "Microcontroller.h"	  //for registers, config data & stdio

#define BUFFSIZEout  62     //should be a multiple of 31 (16 bit integers)
#define BUFFSIZEin   62		//  for optimal transmission speed


//Global variables available to other modules
int USBtimeout = USBtimeoutLimit; 		//measures time since last laptop msg rec'd

extern int BiteMode;

//----------------------------------------------------------------------------
//CRC16 lookup table   (not currently used)
// from  http://www.summitinstruments.com/library/tn410.htm
const unsigned int CRCtbl[ 256 ] = {                                 
   0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,   
   0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,   
   0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,   
   0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,   
   0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,   
   0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,   
   0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,   
   0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,   
   0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,   
   0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,   
   0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,   
   0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,   
   0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,   
   0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,   
   0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,   
   0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,   
   0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,   
   0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,   
   0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,   
   0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,   
   0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,   
   0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,   
   0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,   
   0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,   
   0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,   
   0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,   
   0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,   
   0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,   
   0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,   
   0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,   
   0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,   
   0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040 }; 
                                                                     
//The CRC of a block of data is calculated by initializing the CRC to zero 
//and calling addCRC to add sequential bytes from the block to the CRC. 
//  e.g.  CRC16 = addCRC(CRC16,byte);   //for each byte
unsigned short addCRC( unsigned short CRC, unsigned char b )         
   {    
     return ( CRC >> 8 ) ^ CRCtbl[ ( CRC & 0xFF ) ^ b ];               
   }                                                                 
//----------------------------------------------------------------------------
//Global variables accessible only to this file)
union buffouttag   			  	      //data output message
{
  int   Int[BUFFSIZEout];
  long Long[BUFFSIZEout/2];
} buffout;
  
static char buffin[BUFFSIZEin*2];	//input buffer size in bytes
char BuffIn[BUFFSIZEin*2];			//export version of input buffer
char *buffptr;						//char* to the int buffers(used in CRC calc)
int USBsendidx;						//index to USB output message in bytes
int USBreadidx;						//index to USB input message in bytes

//External globals 
extern int time;
extern int Analog0,Analog1,Analog2,Analog3,Analog4,Analog5,Analog6,Analog7,
           Analog8,Analog9,Analog10,Analog11,Analog12;
extern int RC_Sonar[7];
extern int PitchDeg,RollDeg;
extern int AccelX, AccelY;
extern int YRatedps,hdgdeg,Compass,headingDR;		 
extern int SpeedL,SpeedR;
extern long DistActL,DistActR;
extern long Xcoord,Ycoord;
extern int  seqnumUSB;
extern int  FwdModeDone; //from Motors.c
extern int  TurnModeDone; //from Motors.c
extern long DistCmd;  //temporary test
extern int FwdCmdCurrent; //from ProcessCmds
extern int TurnCmdCurrent; //from ProcessCmds
extern int seqnumCurrent;
extern int DIOdata;
extern int ucStatus;
//---------------------------------------------------------------------------
// converts between VC++ short int (16 lsb) and ICC12 int by reversing bytes

int Word(char* ptr)
{
    return ((int) *(ptr+1)<<8)|(*ptr & 0xFF);
}

//---------------------------------------------------------------------------
// converts between VC++ int/long and ICC12 long by reversing bytes

long Long(char* ptr)
{
 	long temp;
	temp =   (long) *(ptr+3)<<24;
	temp |= ((long) *(ptr+2)<<16)&0x00FF0000;
	temp |= ((long) *(ptr+1)<< 8)&0x0000FF00;
	temp |=  *(ptr)&0x00FF;
    return temp;
}

//--------------------------------------------------------------------------
void USBinit()     
/*Set up USB interface parallel port and reads the receive buffer til empty
    Port B is the byte wide parallel I/O port
	Port A is the control signals
	   Bit 0 = RD#	   (output, ic to high)
	   Bit 1 = WR	   (output, ic to low)
	   Bit 2 = TXE#    (input)
	   Bit 3 = RXF#	   (input)
	   Bits 4 - 7	   (used for sonar)
*/	     
  { int count = 0;	   		//counts buffer purge attempts since runs forever
  			  				//if no usb connection
  
  	PORTB =  0x00;  		  	     //ic  data to zero
	DDRB  =  0x00;				 	 //ic data port to input
	PORTA =  0x01;				 	 //ic control bits
	DDRA |=  0x03;				 	 //ic output control bits
	DDRA &= ~0x0C;				 	 //      "
    USBsendidx = BUFFSIZEout*2;		 //ic as if last message is completed
	
	while((~PORTA & 0x08)&& (count < 256))  			 //purge USB buffer
	{ PORTA &= ~0x01;   			 //RD strobe on
	  PORTA |=  0x01;				 //RD strobe off
	  count++;
	}
  }

//--------------------------------------------------------------------------
// Fill output message with current data and calculate checksum
void  USBmsgfill(void)
  {	  				  
    int CRC16;		   				 //CRC16 value
	int i;		  		   			 //loop counter