pll_rtdx.c

DSP原理及其C编程开发技术的源码 真的很好呀

/* pll_RTDX.c Software Linear PLL 6211 Program With RTDX		*/
/* Upendra Ummethala and Mike Mellor                           	*/
/* December 19, 2000 EE539 Real Time DSP Final Project       	*/

#define N 8000	
#include "sin8000_table.h"/* Sine wave digitized to 8000 points */

#include <rtdx.h>				/* RTDX_Data_Write...			*/
#include <stdio.h>				/* puts message at end			*/
#include <target.h>				/* TARGET_INITIALIZE			*/
                                
#define MAX_MESSAGES 1000  		/* Total number of steps 		*/  
#define PHASE_STEP_COUNT 4	 	/* #cycles+1 before phase step  */
#define MAX_ELEMENTS 5

/*  The variable names used below are from Chapter 5 in  		*/
/*  the book: Phase-Locked Loops by Roland Best          		*/
/*  Fourth edition McGraw-Hill                           		*/

int u1_n;						/* Input signal at time n 		*/
int u2_n=0;                     /* DCO output signal at time n  */                            	
int u2_nplus1;                  /* DCO output signal at n+1		*/
int phi2_n=0;					/* DCO output phase at time n 	*/
int phi2_nplus1;        	    /* DCO output phase at n+1		*/
int ud_n_1=0;                   /* Phase detector output at n-1	*/
int ud_n;                       /* Phase detector output at n	*/
int uf_n_1=0;                  	/* Loop filter output at n-1	*/
int uf_n;                       /* Loop filter output at n 		*/	                                  	
int inp_freq=100;  				/* Input sine freq = 100Hz		*/        
int table_index=0; 				/* Index into the sine table	*/
int w0= 628;      				/* 100Hz = 628 rad/s target freq*/
int K0= 1;        				/* VCO Gain scaled up by ~2^6	*/
int uf_n_tmp;     				/* Tmp to scale	uf_n down by 2^6*/
int cycle_count=0;              /* Number of sine cycles		*/
int pi_scaled=25133; 			/* PI scaled by 8000 Hz rate	*/
int A1 = -4002;		/* Loop filter coefficient scaled up by 2^12*/
int B0 = 4348;		/* Loop filter coefficient scaled up by 2^12*/
int B1 = -3784;		/* Loop filter coefficient scaled up by 2^12*/
     
RTDX_CreateOutputChannel(ochan);/* Open RTDX output data channel*/

void main()
{
	int x;						/* Loop index variable			*/

	TARGET_INITIALIZE();		/* Initialize the DSP for RTDX	*/

	RTDX_enableOutput(&ochan);	/* Enable RTDX ouput data channel*/
                                                                                                                                                  
	                            /* Main program loop			*/ 
	for ( x=0; x<MAX_MESSAGES; x++)                            			
    {
		int message[MAX_ELEMENTS]; /* Data output array         */
    	
		 									/* Create scaled input*/
		 u1_n=31*sin8000_table[table_index];/* from sine table  */

		 message[0] = x;  	/* Save sample count for RTDX output*/						
		 message[1] = u1_n; /* Save input sample for RTDX output*/
		                                 
		                                 
		                              /* Phase or Freq Step Input*/   
		 	                          /* After PHASE_STEP_COUNT */
         if(cycle_count >PHASE_STEP_COUNT)/* cycles at this 	*/
			{	                 		/* phase give either	*/
/*         	table_index += (N >> 2);*/  /* a 90 deg phase step  */
            inp_freq += 50;				/* or a 50Hz freq step  */                        
         	cycle_count = 0;	 		/* Reset cycle count. 	*/
        	}                        
                                           
		 table_index=table_index+inp_freq;/* Increment phase	*/

		 if(table_index >= N)	 
        	{	                    /* Unwrap phase if 2*pi range  */
        	table_index -= N;   	/* is exceeded, i.e. modulo N */
        	cycle_count++; 			/* Count cycles at phase wrap */
        	}
                         		
		  ud_n=u1_n*u2_n;      		/* Phase detector output 	*/
		  uf_n=-A1*uf_n_1+B0*ud_n+B1*ud_n_1; /* Filter output	*/
		  uf_n=uf_n>>12;     		/* Scaled down filter output*/
		  uf_n_tmp=uf_n>>6;  		/* Undo VCO Gain(K0) scaling*/

		                            /* Calculate next DCO output*/
		                            /* phase for time n+1		*/ 
		  phi2_nplus1=phi2_n+(w0+K0*uf_n_tmp);
		                                
		                            /* Maintain -pi to +pi range*/
		                            /* for next DCO phase		*/    
		  if (phi2_nplus1>pi_scaled)	/* If next DCO phase>pi	*/
		  phi2_nplus1=phi2_nplus1-2*pi_scaled; /* unwrap by 2*pi*/  
		                               
		  if (phi2_nplus1>=0)  	/* If next DCO phase is positive*/		  
		  u2_nplus1=1; 			/* DCO output=+1(Walsh function)*/
		  else                  /* If next DCO phase is negative*/
		  u2_nplus1=-1; 		/* DCO output=-1(Walsh function)*/ 
                                
                                /* Save following for RTDX ouput*/
         message[2] = uf_n;		/* Scaled down loop filter ouput*/
         message[3] = u2_n*31000; 	/* Scaled DCO Output 		*/
		 message[MAX_ELEMENTS-1] = x; /* Sample count again		*/
		 						/* The sample count brackets the*/
		 						/* other data and is sent twice */
		 						/* with RTDX to ensure all the	*/
		 						/* data sent to the host came	*/
		 						/* from the same time stamp		*/  
                                
                                /* Send RTDX data array to host */
		RTDX_write( &ochan, message, sizeof(message) );	

		while ( RTDX_writing != NULL )
        {
#if RTDX_POLLING_IMPLEMENTATION
			RTDX_Poll();		/* Wait for array to be xferred	*/
#endif
		}
		  
					/* Update values for next pass through loop	*/  
		  ud_n_1=ud_n;     		/* Phase detector: ud(n-1)=ud(n)*/
		  uf_n_1=uf_n;          /* Filter ouput: uf(n-1)=uf(n)	*/
		  phi2_n=phi2_nplus1;   /* DCO phase: phi2(n)=phi2(n-1)	*/
		  u2_n=u2_nplus1;       /* DCO output: u2(n)=u2(n+1)	*/
	}   

	RTDX_disableOutput(&ochan);	/* Disable RTDX output channel	*/

	puts("\rTest Completed");   /* Tell user data is gathered	*/
		
}